Dissertations / Theses on the topic 'Wine and winemaking'

Thesis (MScAgric)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Glutathione (GSH), a tripeptide consisting of glutamate, cysteine and glycine, is the most ubiquitous non‐protein intracellular thiol in a large variety of organisms, including plants, animals and fungi. The thiol moiety of the cysteine residue confers unique redox and nucleophilic properties. In plant cells, GSH fulfils an indispensible role in the antioxidant system, sulphur metabolism and detoxification of xenobiotics. Upon grape crushing, GSH is extracted into the juice where it exerts several protective effects during the vinification process. In must, it reacts with oxidized phenolic compounds to form the colourless grape reaction product (GRP) which limits must browning to a certain extent. During wine ageing, GSH impedes the decrease of important aroma compounds, including certain esters, terpenes and volatile thiols, while at the same time preventing the development of atypical ageing off‐flavours. GSH may also inhibit the yellowing of wine during ageing. It is thus evident that elevated GSH levels in wine, in particular white wine which is more sensitive to oxidation, may be highly valuable for wine quality. The reductive crushing and pressing of white grape varieties, which limits oxidation and the consequent incorporation of GSH into GRP, promotes higher GSH levels in the juice. The reductive handling of juice also limits the formation of oxidized glutathione (GSSG). However, during alcoholic fermentation and maturation, levels generally decrease as a result of assimilation by the yeast Saccharomyces cerevisiae, and inevitable oxidation that takes place during the vinification process. The principal focus of this study was to gain a better understanding of the fate of glutathione during alcoholic fermentation and to establish whether certain oenological applications could result in elevated wine GSH levels. The application studied, included choice of yeast strain, extended lees contact, nitrogen supplementation and supplementation with glutathione enriched inactive dry yeast preparations (GHS‐IDYs). In addition, the need for a rapid analytical method for the simultaneous quantification of both GSH and GSSG in must and wine which does not involve derivatization or require extensive sample preparation, led to the development of a novel UPLC‐MS/MS method. The method was also employed to determine intracellular GSH and GSSG contents of the yeast S. cerevisiae and was studied for the first time in winemaking conditions. It was shown that the GSH levels fluctuated during alcoholic fermentation, suggesting the uptake and release by yeast. At the end of alcoholic fermentation, levels were generally lower than those initially present in grape juice, but in some cases, concentration increases were also observed. This finding indicates that, in some cases, endogenously‐produced GSH may be secreted into must during alcoholic fermentation, contributing to higher GSH levels in wine. Albeit small, significant differences in GSH content could be seen in wines fermented with different yeast strains, implying that yeast strain may to a certain extent influence wine GSH levels. While the effects of lees ageing and nitrogen supplementation seem to be insignificant in contributing to higher GSH levels in wine, the supplementation of must with GSH‐IDYs could result in increased wine GSH levels, provided the supplementation is done early during fermentation. This study has broadened our knowledge of several oenological factors, influencing GSH levels in wine and provided a new baseline for future research studies.
AFRIKAANSE OPSOMMING: Glutatioon (GSH), ’n tripeptied bestaande uit glutamaat, sisteïen en glisien, is die mees algemene nieproteïenagtige intrasellulêre tiool in ‘n wye verskeidenheid organismes, insluitende plante, diere en fungi. Die tioolfunksiegedeelte van die sisteïenresidu verleen unieke redoks‐ en nukleofiliese eienskappe. GSH vervul ‘n onmisbare rol in die antioksidantsisteem, swaelmetabolisme en die ontgiftiging van xenobiotika in plantselle. Tydens die maal van druiwe word glutatioon in die sap geëkstraeer waar dit verskeie beskermende effekte tydens die wynbereidingsproses uitoefen. GSH reageer met geöksideerde fenoliese verbindings om die kleurlose druifreaksieproduk (DRP) te vorm wat die verbruining van mos in ‘n sekere mate beperk. GSH verminder ook die afname van belangrike aromaverbindings tydens wynveroudering, insluitende sekere esters, terpene en vlugtige tiole, terwyl dit terselfdertyd die vorming van atipiese verouderingswangeure belemmer. So ook kan GSH die vergeling van wyn tydens veroudering inhibeer. Dit is dus voor die hand liggend that verhoogde GSH‐vlakke in wyn, in die besonder witwyn, wat meer oksidasie‐sensitief is, van waarde kan wees vir wynkwaliteit. Die reduktiewe maal en pers van witdruifvariëteite wat oksidasie en gevolglike inkorporasie van GSH in DRP beperk, bevorder hoër GSH‐vlakke in sap. So ook beperk die reduktiewe behandeling van sap die vorming van geoksideerde glutatioon (GSSG). Gedurende alkoholiese gisting en veroudering neem GSH‐vlakke egter af as gevolg van assimilasie deur die gis, Saccaromyces cerevisiae, asook onvermydelike oksidasie wat gedurende die wynbereidingsproses plaasvind. Die hooffokus van die studie was om ‘n beter begrip van die lot van glutatioon tydens alkoholiese gisting te verkry en om vas te stel of sekere wynkundige praktyke verhoogde GSH‐vlakke in wyn tot gevolg kan hê. Die studie het gisraskeuse, verlengde gismoerkontak, stikstofaanvulling en aanvulling met glutatioon‐verrykte, onaktiewe droëgis ingesluit. Daarbenewens het die behoefte aan ‘n vinnige analitiese metode vir die gelyktydige kwantifisering van sowel GSH as GSSG in mos en wyn wat nie derivatisering of uitgebreide monstervoorbereiding vereis nie, gelei tot die ontwikkeling van ‘n nuwe UPLC‐MS/MS metode. Hierdie metode is ook gebruik om die intrasellulêre GSH‐ en GSSG‐inhoud van die gis S. cerevisiae te bepaal wat vir die eerste keer in wynbereiding bestudeer is. Daar is bewys dat GSH‐vlakke tydens alkolholiese gisting fluktueer, wat dui op die opname en vrystelling daarvan deur die gis. Die vlakke aan die einde van alkoholiese gisting was oor die algemeen laer as vlakke aanvanklik teenwoordig in die sap. In sommige gevalle is konsentrasietoenames egter ook waargeneem. Hierdie bevinding dui daarop dat intrasellulêr‐vervaardige GSH, in sommige gevalle, in die mos uitgeskei kan word, wat tot hoër GSH‐vlakke in wyn lei. Klein, dog beduidende verskille in GSHinhoud is waargeneem in wyne wat met verskillende gisrasse berei is, wat daarop dui dat gisras in ‘n sekere mate die GSH‐vlakke in wyn kan beïnvloed. Alhoewel die effek van gismoerveroudering en stikstofaanvulling onbeduidend is, kan die aanvulling van mos met glutatioon‐verrykte, onaktiewe droëgis tot verhoogde GSH‐vlakke in wyn lei, mits die aanvulling vroeg tydens alkoholiese gisting gedoen word. Hierdie studie verbreed ons kennis van verskeie wynkundige praktyke wat GSH‐vlakke in wyn beïnvloed en vorm ‘n nuwe basis vir toekomstige navorsingstudies.

One of the most widely consumed beverages in many parts of the world is wine, which has been well-known since the early periods of civilization. Besides its economical importance, this beverage can have a positive impact on human health, including the anti – cancer effect. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/31701

Thesis (MSc Food Sc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: South Africa is a developing country that relies on its agricultural sector as a main source of overall economic welfare. Development does not only give rise to new technology and new products but also results in increased amounts of liquid and solid waste. Generally, the production of wine is considered an environmentally friendly process, but significant amounts of natural resources and organic amendments are necessary, while generating large amounts of liquid and solid wastes. Anaerobic digestion (AD) is an attractive and proven treatment option for both liquid and solid wastes as valuable products and depollution can be obtained. AD of liquid waste results in an effluent and biogas, while anaerobic composting of solid waste results in an organic amendment, leachate and biogas. The overall objective of this study was to investigate the operational feasibility of the cotreatment of leachate produced during the anaerobic composting (AnC) of grape skins in an upflow anaerobic sludge blanket (UASB) reactor while treating winery wastewater. This first aim of this study was to investigate the efficiency of the anaerobic composting of grape skins. Laboratoryscaled digesters (1L) were utilised as anaerobic composting units. The most important operational parameters were identified (pH, moisture content and inoculum (size, ratio, composition)) in order to produce a pH stable, odour free compost in 21 days. Experimental studies highlighted the importance of shredding waste as well as the addition of calcium oxide and green waste to increase the initial pH of the composting mixture. After optimising a 50% (m.m-1) cow manure inoculum, lower inoculum concentrations (10, 15 and 25% (m.m-1)) were investigated to make the process more economically viable. A 10% (m.m-1) anaerobic compost (AC) inoculum was found to produce the most favourable results in terms of pH stabilisation and leachate generation. A 50% (m.m-1) moisture level performed the best by attaining a pH > 6.5 on day 6 and having the highest end pH (7.65) on day 21, while white and red grape skins in an equal ratio were found to generate a higher end pH. With all these optimum parameters in place (shredded waste, green waste, CaO, inoculum, moisture, grape skins), a compost with a final pH (7.09), moisture (58%), nitrogen (2.25%), phosphorous (0.22%) and potassium content (1.7%) was obtained. The optimised parameters were scaled-up (1:10) by using polyvinyl chloride anaerobic digesters (20 L) to suit the operational requirements of the AnC process and also produced a stable compost within 21 days. The second aim of this study was to investigate the combined anaerobic digestion of winery wastewater (WWW) and leachate obtained from the anaerobic composting of grape skins in an upflow anaerobic sludge blanket (UASB). This involved the operation of a 2.3 L laboratory-scale UASB reactor for 205 days. The reactor successfully co-treated WWW and leachate at ca. 8.5 kgCOD.m-3d-1 with a final chemical oxygen demand (COD) reduction of over 90%, a stable reactor effluent pH (7.61) and alkalinity (3 281 CaCO3 mg.L-1). This study showed the feasibility for the combined treatment of liquid and solid waste from the winemaking process. Although the legal limits for reactor effluent disposal onto land was not met, significant reduction in COD concentrations were achieved, whilst producing a soil amendment that could potentially result in cost savings for chemical fertilisers. The benefits related to using anaerobic bioconversion as a treatment option for liquid and solid waste could possibly be advantageous to the wine industry as an environmental control technology, by converting liquid and solid waste into valuable resources.
AFRIKAANSE OPSOMMING: Suid-Afrika is 'n ontwikkelende land wat staatmaak op sy landbousektor as 'n hoofbron van algehele ekonomiese welstand. Ontwikkeling gee nie net aanleiding tot nuwe tegnologie en nuwe produkte nie, maar lei ook tot die verhoogde bydrae van vloeistof sowel as vaste afval. Oor die algemeen, word die produksie van wyn beskou as 'n omgewingsvriendelike proses, maar aansienlike hoeveelhede natuurlike hulpbronne en organiese kunsbemesting word benodig, terwyl groot hoeveelhede vloeistof en vaste afval gegenereer word. Anaërobiese vertering (AV) is 'n aantreklike en bewese behandelingsopsie vir beide vloeistof en vaste afval aangesien waardevolle produkte en suiwering verkry kan word. AV van vloeistowwe lewer uitvloeisel sowel as biogas, terwyl anaërobiese kompostering van vaste afval 'n organiese kunsbemesting, loog en biogas lewer. Die oorhoofse doel van hierdie studie was om die operasionele doeltreffendheid van die mede-behandeling van loog wat gegenereer word tydens die anaërobiese kompostering (AnK) van druiwe doppe in 'n opvloei-anaërobiese-slykkombers (OAS) reaktor terwyl kelderafvalwater behandel word, te ondersoek. Die eerste mikpunt van hierdie studie was om die doeltreffendheid van die anaërobiese komposteringsproses van druiwe doppe te ondersoek. Laboratorium-skaal verteerders (1L) is gebruik as anaërobiese komposteringseenhede. Die belangrikste operasionele parameters is geïdentifiseer (pH, voginhoud en inokulum (grootte, verhouding, samestelling)) om ‘n 'n pH-stabiele, reukvrye kompos te produseer in 21 dae. Die belangrikheid van gesnipperde afval asook die byvoeging van kalsiumoksied en groen afval om die aanvanklike pH van die komposmengsel te verhoog, is deur eksperimentele studies beklemtoom. Na die optimering van 'n 50% (m.m-1) koeimis inokulum, is laer inokulum konsentrasies (10, 15 en 25% (m.m-1)) geondersoek om die proses meer ekonomies uitvoerbaar te maak. Daar is gevind dat ‘n 10% (m.m-1) anaërobiese kompos (AK) inokulum die mees gunstige resultate lewer in terme van pH stabilisering en loog generering. ‘n 50% (m.m-1) vloeistof vlak het die beste presteer deur 'n pH> 6.5 te bereik teen Dag 6 asook die hoogste eind pH (7.65) teen Dag 21, terwyl wit en rooi druiwe doppe in dieselfde verhouding gevind is om ‘n hoër eind pH te genereer. Met al hierdie optimum parameters in plek (gesnipperde afval, groen afval, kalsiumoksied, inokulum, vog, druiwe doppe) is 'n kompos met 'n finale pH (7.09), vog (58%), stikstof (2.25%), fosfor (0.22%) en kalium inhoud (1.7%) verkry. Die optimale parameters is opgeskaal (1:10) deur gebruik te maak van polivinielchloried anaërobiese verteerders (20 L) om aan die operasionele vereistes van die AnK proses te voldoen en ook om 'n stabiele kompos binne 21 dae te produseer. Die tweede mikpunt van hierdie studie was om die gekombineerde anaërobiese vertering van kelderafvalwater en loog, verkry vanaf die anaërobiese kompos van druiwe doppe in 'n OAS reaktor, te ondersoek. Dit het die bedryf van 'n 2.3 L laboratorium-skaal OAS reaktor vir 205 dae ingesluit. Die reaktor het kelderafwater en loog suksesvol behandel by ongeveer 8.5 kgCSV.m-3d-1 met 'n finale chemiese suurstof vereiste (CSV) vermindering van meer as 90%, 'n stabiele reaktor uitvloeisel pH (7.61) en alkaliniteit (3 281 CaCO3mg.L-1). Hierdie studie het die uitvoerbaarheid van die gekombineerde behandeling van vloeistof en vaste afval van die wynmaakproses getoon. Alhoewel die wetlike vereistes van die reaktor uitvloeisel vir storting op grond nie bereik is nie, is ‘n beduidende vermindering in CSV konsentrasies bereik, asook die vervaardiging van kunsbemesting wat die potensiële aankoopkoste van chemiese kunsmis kan verminder. Die voordele verbonde aan die gebruik van anaërobiese bio-omskakeling as 'n behandelingsopsie vir vloeistof en vaste afval kan moontlik voordelig wees vir die wynbedryf as 'n omgewingsbeheerende tegnologie deur om vloeistof en vaste afval om te skakel na waardevolle bronne.

Thesis (MSc)--Stellenbosch University, 2007.
ENGLISH ABSTRACT: With ever increasing pressure on wine producers to lower the financial costs involved in winemaking to be able to compete in the market, all while maintaining a high level of wine quality, the focus on maintaining control over all aspects of the winemaking process are greatly emphasized. Malolactic fermentation (MLF) is one of the important processes in red wine production. The advantages of this process, when performed successfully, is widely known and accepted. One way to gain control over MLF is the use of MLF starter cultures. Starter cultures usually consist of Oenococcus oeni that has been isolated from grapes or wines and is in most cases available in a freeze-dried form ready for direct inoculation into the wine when MLF is desired. Starter cultures are induced into wine and usually ensure the immediate onset as well as a fast and clean execution of the process. Starter cultures used in South Africa are in most cases isolated from cooler viticultural regions in the Northern hemisphere. The constitution of wines from cooler viticultural regions, differ from those in South Africa, which has a warm climate. The most important difference is the acid content of the wines which is lower in South African must/wines and results into a higher pH. The three most important changes that develop in wine during MLF are a decrease in acidity due to the conversion of malic acid to the less harsh lactic acid, enhanced flavour and aroma of wine and an increase in the microbiological stability of wine. The decrease in acidity is very important for wines produced for grapes grown in cool viticulture regions. In South Africa though, the climate is warm and higher pH’s are present in the musts and wines and the de-acidification due to MLF is not the main aim but rather the microbiological stabilisation. One of the compounds that could be produced by lactic acid bacteria (LAB) is biogenic amines (BA’s). These compounds can be hazardous to human health. This thesis focussed on the performance of MLF starter cultures in high pH South African red wines. The first objective of the study was to stretch MLF starter cultures in high pH red wines of South Africa. Stretching means to use less than the prescribed dosage or the re-use of starter cultures. The difference in MLF rate, the influence of the natural occurring LAB and the levels of biogenic amines formed during MLF were determined for the different stretching treatments. The results showed that different rates in malic acid degradation were experienced between the treatments, but in all cases MLF fermentation was completed. Biogenic amines were formed at various levels and the influence of the natural occurring LAB also played a role. The second objective of the study was the evaluation of the effect of a wine isolated LAB (Lactobacillus) and an acetic acid bacteria (AAB), inoculated with a MLF starter culture had on MLF at different wine pH’s. It was found that especially in the case where the Lactobacillus was inoculated in combination with the MLF starter culture a possible stimulatory effect was experienced with regards to malic acid degradation rate. Biogenic amine concentration was measured at the end of MLF and it was found that no histamine and tyramine were formed in any of the treatments, while the putrescine and cadaverine levels were found to be at approximately similar levels for the different treatments. The third objective was to evaluate the possible influence of commercial tannin additions and a pectolytic enzyme on rate of MLF and phenolic composition of high pH red wine. The commercial tannins had possible inhibitory as well as stimulatory effects on the rate of malic acid degradation especially during the initial stages of MLF, with the highest dosage having the significant effect. The BA results showed difference in the levels produced due to tannin additions as well as strain differences could exist. The phenolic content showed a decrease in colour density, total red pigments, total phenolics and anthocyanins between AF and MLF. The fourth objective was to evaluate inoculation time of MLF starter cultures. The results showed that the fastest AF/MLF time was with simultaneous inoculation of the yeast and MLF starter cultures. It was also for this treatment where no histamine or tyramine was detected at the end of MLF compared to the other inoculation strategies (before the end of AF and after AF). This study generated a large amount of novel data which made a valuable contribution with regards to MLF in high pH red wines of South Africa.
AFRIKAANSE OPSOMMING: Die druk om wyne van hoë gehalte teen lae insetkoste te lewer om deel te bly van ’n kompeterende mark, plaas die fokus weer sterk op onder andere die beheer van alle aspekte van die wynmaak proses. Appelmelksuurgisting (AMG) is een van die belangrikste prosesse van rooiwyn produksie. Die voordele van AMG, in die geval van die suksesvolle implementering daarvan is vandag bekend en word geredelik aanvaar. Een van die metodes om beheer te verkry oor the proses van AMG is deur die gebruik van AMG aanvangskulture. AMG aanvangskulture bestaan uit Oenococcus oeni wat geïsoleer word vanaf druiwe of mos/wyn en is in meeste gevalle beskikbaar in ’n gevries-droogte vorm wat direk in wyn geïnokuleer kan word. Aanvangskulture word in wyn geïnduseer om die onverpose aanvang van AMG te bewerkstellig asook om ’n vinnige en skoon deurvoering van die proses te verseker. Die aanvangskulture wat in Suid-Afrika vir hierdie doeleinde gebruik word is in meeste van die gevalle verkry uit koue wingerdbou gebiede in die Noordelike Halfrond. Die samestelling van druiwe van koue wingerdbou gebiede en dié van Suid-Afrikaanse warm wingerdbou gebiede verskil. Die belangrikste verskil word ervaar in die suur inhoud, wat laer is in Suid-Afrikaanse druiwe en dus lei tot ‘n hoër pH inhoud. Die drie mees belangrikste veranderinge wat gedurende AMG in wyn plaasvind is die vermindering van die suur, as gevolg van die omskakeling van appelsuur na melksuur, die verbetering van die aroma en geur van wyn en die verbeterde mikrobiologiese stabiliteit. Die afname in suur is veral belangrik in wyne van koue wingerbou gebiede omdat die suur-inhoud daarvan soveel hoër is. In Suid-Afrika kan hierdie verlaging in suur egter lei tot ’n verdere verhoging in die pH wat plat wyne en uiteindelik ’n verlaging in die kwaliteit van wyn tot gevolg kan hê. Biogene amiene (BA) is verbinding wat melksuurbakterieë (MSB) kan vorm gedurende AMG en kan ernstige implikasies hê vir die mens se gesondheid. Hierdie tesis fokus op die evaluering van AMG aanvangskulture in hoë pH rooi wyne van Suid-Afrika. Die eerste doelwit gedurende hierdie studie was om AMG kulture te rek en die invloed daarvan in hoë pH rooiwyn te evalueer ten opsigte van the tempo van AMG, die rol van die natuurlike MSB te bestudeer asook om die vlak van biogene amiene te bepaal vir die verskillende behandelings. Die resultate het aan die lig gebring dat die rek van kulture verskille in die tempo van appelsuur afbraak tot gevolg het, maar dat AMG in alle gevalle wel suksesvol deurgevoer kon word. Die BA’e wat gevorm is, was teenwoordig in verskillende hoeveelhede. Die tweede doelwit was om die effekt van die gesamentlike inokulasie van ’n wyn geisoleerde MSB (Lactobacillus) asook ’n asynsuurbakterie (ASB) met ’n kommersiële AMG aanvangskultuur op AMG te evalueer. Hierdie eksperiment is uitgevoer by verskillende pH’s. Daar is gevind dat veral in die kombinasie inokulasie met die Lactobacillus, die tempo van appelsuur afbraak moontlik gestimuleer was. Geen histamien of tiramien is tydens AMG gevorm in hierdie eksperiment gevorm nie, terwyl putresien en kadaverien teenwoordig was teen ongeveer gelyke vlakke vir die behandelings. Die derde doelwit was om die moontlike invloed van kommersiële tannien toevoegings en die toevoeging van ’n pektolitiese ensiem te evalueer ten opsigte van AMG tempo die fenoliese samestelling van rooiwyn te bestudeer. Verskillende kommersiële tanniene het ’n moontlike sowel as inhiberende uitwerking gehad, veral gedurende die aanvanklike stadium AMG. Die grootste verskille is waargeneem in die behandelings waar die hoogste dosisse tannien bygevoeg is. Die BA resultate toon dat verkillende vlakke geproduseer was en dat hierdie verskille onstaan het as gevolg van verskille in tannien dosisse sowel as aanvangskulture. Die fenoliese inhoud het ’n afname in kleur intensiteit, totale rooi pigmente, totale fenole en antosianiene getoon vir die periode vanaf AF tot die einde van AMG. Die vierde doelwit was om the tyd van inokulasie van AMG aanvangskulture te bestudeer. Die resultate het getoon dat die vinningste tydperk van AF/AMG was ondervind in die geval waar die gis aanvangskulture gelyktydig met die AMG aanvangskulture geïnokuleer was. Geen histamine en tyramine het ook in hierdie behandeling ontwikkel nie, terwyl daar wel vlakke teenwoordig was in die ander behandelings (inokulasie net voor die einde van AF en na afloop van AF). Tydens hierdie studie is ’n groot hoeveelheid nuwe data geskep wat ‘n groot bydrae ten opsigte van AMG in hoë pH rooi wyne vanaf Suid-Afrika kan lewer.

Thesis (MSc (Wine Biotechnology))--University of Stellenbosch, 2007.
Bacteriocins are ribosomally synthesized antimicrobial peptides produced by bacteria and are active against other bacteria, either in the same species (narrow spectrum) or across genera (broad spectrum). The application of bacteriocins during the vinification process might help to prevent the production of undesired compounds by inhibiting the indigenous bacterial microflora and allowing malolactic fermentation to be conducted by a selected bacterial strain. Furthermore, the use of bacteriocins might allow reducing the total sulphur dioxide amount in wine. The purpose of this study was the selection of lactic acid bacteria (LAB) belonging to the genera Oenococcus, Lactobacillus and Pediococcus with the ability to produce bacteriocins, with respective biological activity against undesired indigenous wine LAB and the capability to complete malolactic fermentation. The first objective of this study was the screening of LAB isolated from South African red wines for the production of bacteriocins. Only 27 strains out of 330 wine isolates, belonging to the species Lb. plantarum, Lb. paracasei, Lb. hilgardii and O. oeni, showed activity towards various wine-related and non wine-related indicator strains with the colony-overlay method. It is the first time that bacteriocin activity is reported in O. oeni. The second objective was the detection and identification of known structural bacteriocin genes of Lb. plantarum wine strains. Furthermore, the web server BAGEL was used to in silico analyse putative bacteriocin-encoding genes in the genome of O. oeni and primers were designed to amplify four possible bacteriocin-encoding genes. A PCR-based screening revealed the presence of the plantaricin encoding genes plnA, plnEF, plnJ and plnK in five selected Lb. plantarum strains. Moreover, PCR analysis rendered positive results with all four chosen putative bacteriocin-encoding genes in the eight tested O. oeni strains with antimicrobial activity. The latter genes of O. oeni were heterologously expressed in different Escherichia coli host strains, but no antimicrobial activity could be detected. The third objective of this study was the transformation and expression of the heterologous bacteriocin genes nisin A and pediocin PA-1 in two selected Lb. plantarum strains. To enhance their antimicrobial activity a plasmid containing the nisin A gene was successfully cloned into the two strains. Indeed, an enhanced antimicrobial activity could be detected, but the transformed plasmid was not stable. The fourth objective in this project was the evaluation of bacteriocin production in liquid media. A co-culture experiment with a plantaricin producing Lb. plantarum strain and an Enterococcus faecalis strain as indicator was performed. A complete inhibition of cell growth of Ent. faecalis was observed within 72 hours. The last objective was the evaluation of the impacts of phenolic compounds on the activity of nisin and pediocin. The short term influence of two phenolic acids, two flavan-3-ols, grape tannins and oak tannins on the activity of nisin and pediocin PA-1 was investigated. No influence on the activity was detected. Furthermore, synergistic effects on bacterial growth inhibition were observed. This study confirms the potential use of either bacteriocin additives or bacteriocin-producing LAB in order to control the bacterial microflora during the vinification process.

In questo lavoro è stato investigato l'utilizzo di moderne tecnologie applicate alle metodologie tipiche della tradizione enologica. Le analisi svolte mirano ad approfondire la conoscenza delle modificazioni chimiche e sensoriali che si verificano nel vino e ne influenzano la qualità. In particolare questa tesi di dottorato si focalizza su tre diversi aspetti della vinificazione: I) L'impatto del tipo di contenitore utilizzato in vinificazione (durante e dopo la fermentazione). Lo studio si è concentrato sul confronto tra vini Chardonnay ottenuti con anfore di terracotta e contenitori di legno. I risultati hanno mostrato che il vino in anfora si distingue per il caratteristico profilo fenolico, volatile e sensoriale permettendo di differenziarsi dal vino prodotto in contenitori di legno. L’esito di questo studio mostra la possibilità di sviluppare un nuovo stile di vino Chardonnay ottenuto attraverso anfore di terracotta. II) L'influenza del tipo di tappo durante la conservazione in bottiglia: l'indagine ha riguardato il confronto tra vini chiusi con un nuovo tipo di tappo in microgranulo di sughero senza aggiunta di colla e tappi convenzionali in sughero. Il profilo fenolico, volatile e sensoriale è stato monitorato durante un periodo di conservazione in bottiglia di 12 mesi. I risultati dell'analisi evidenziano l'influenza dominante del tempo di conservazione rispetto al tipo di tappo sulle caratteristiche chimico-sensoriali del vino. Tuttavia, il confronto tra diversi tipi di tappi permette una migliore comprensione dell’influenza della composizione del tappo sulla conservazione del vino. III) L’effetto dell'associazione di proantocianidine (PAC) cicliche e non cicliche a ioni di potassio e calcio sulla stabilità chimico-fisica dei vini. Lo studio riguarda una nuova classe di proantocianidine con struttura ciclica recentemente scoperta nel vino. Sono state analizzate le proprietà chimiche di legame delle PAC con metalli di calcio e potassio per valutarne l’impatto sulla stabilità colloidale del vino. Il legame con questi metalli risulta influenzato non solo dal numero di unità monomeriche, ma anche dalla conformazione assunta dalle molecole.
The use of modern technologies applied to material and methodologies typical of the winemaking tradition are investigated in this work. The analyzes performed would like to provide helpful insights for extending the knowledge about the changing occurring in wine. Especially, this PhD thesis investigates three different aspects of winemaking: I) The impact of the type of container used during and after the fermentation: the study focused on the comparison between Chardonnay wines obtained with earthenware amphorae and wooden containers. The results showed that in-amphorae wine had a peculiar phenolic, volatile and sensory profile. This discovery allowed differentiating wine obtained through earthenware amphorae from wine made in wooden containers and provided knowledge for the possible development of a new Chardonnay wine-style obtained through earthenware amphorae. II) The influence of the type of stopper during the storage in bottle: the investigation concerned the comparison between wines closed with a new type of stopper made of microgranule cork without glue addition and wines closed with conventional cork-based stoppers. The phenolic, volatile and sensory profile were monitored during a bottle storage period of 12 months. The results of the analysis highlight the dominant influence of the storage time over the type of stopper on the wine composition. However, the comparison between different types of stoppers allowed a better comprehension of their influence on the final product. III) The binding of cyclic and non-cyclic proanthocyanidins (PACs) to potassium and calcium ions, which affect the chemico-physical stability of wines: novel cyclic proanthocyanidins recently discovered in wine, are investigated in the chemical properties to evaluate their impact on the colloidal stability of wine. The binding to these metals appeared to be influenced not only by the number of monomer units, but also by the conformation assumed by the molecules.

La presente tesi di dottorato riporta lo studio, la struttura e l’implementazione presso due aziende pilota di un software, I Wine, realizzato per la gestione delle operazioni di cantina e delle opera-zioni colturali. Il software, progettato per garantire la tracciabilità di prodotto lungo la catena produttiva, grazie alla configurazione per processi, fasi ed attività, consente all’utente finale di impostare il programma secondo le proprie logiche produttive. La struttura delle caratteristiche consente all’operatore di attribuire tutte le informazioni sul prodotto in elaborazione, senza dover modificare il codice base del programma. L’elaborazione e l’implementazione del programma è stata condotta da APRA spa (Jesi, An, Italia), in collaborazione con il dipartimento D3A dell’Università Politecnica delle Marche, nell’ambito del progetto Eureka. Il software è stato im-plementato in due aziende agricole molto diverse tra loro, per testare l’efficacia operativa della piattaforma. La prima, Settesoli (Menfi, AG, Italia) è una cooperativa agricola con 5 stabilimenti produttivi, che vinifica l’uva proveniente dai terreni di oltre 2000 soci conferenti. Il primo caso studio riporta l’implementazione del sistema di gestione della vinificazione, che è stato effettuato in 3 dei 5 stabilimenti produttivi. La seconda, Piovene Porto Godi (Toara di Villaga, VI, Italia) è un’azienda privata che possiede oltre 115 ettari di terreni coltivati a vite ed altre colture, le cui necessità sono quelle di gestire le operazioni colturali. Il secondo caso studio riporta l’implementazione del sistema di gestione delle operazioni in campo. I risultati principali di questo progetto sono l’elevata automazione delle movimentazioni di cantina e di campagna e la possibili-tà di ottenere immediatamente informazioni sulla storia delle lavorazioni dei prodotti in azienda, potendo evidenziare con un sistema di tracciabilità di prodotto, tutti i passaggi che hanno portato alla realizzazione del prodotto finito.
This PhD dissertation reports the study, design and implementation of a software, called I Wine in two pilot companies. The solution has been designed for the winery and farm operations man-agement. The software had to guarantee the product traceability throughout the production chain .The software, designed according to a process-phase-activity structure, allows the end user to configure the program according to his own production logics. The characteristics allow the opera-tor to assign additional information on the product processing, without the duty of modifying the software codes. The elaboration and implementation of the program was performed by APRA (Jesi An, Italy), in collaboration with the Department of Agricultural, Food and Environmental sciences, Polytechnic University of Marche. I participated in the study design, testing and final implementa-tion of the software platform. The software has been implemented in two companies in order to test the operating effectiveness of the platform. The first, Settesoli (Menfi AG, Italy), is a coopera-tive farm with 5 production facilities, which processes the grapes coming from the over 2000 con-ferrers. The first case study reports the implementation of the winery operations management system, on 3 out of the 5 production facilities. The second company, Piovene Porto Godi (Toara di Villaga, VI, Italy) is a private company that owns more than 115 hectares of vineyards and other crops, and needed to manage all the farming operations efficiently. The second case study reports the implementation of the farming operation management system, through which the users can automate the recording of the operations carried out on the company’s lands. The main results of this project were the high automation during the movements recording and the possibility to im-mediately obtain information on the processed products. The software highlighted the steps to the realization of the finished produc, together with the related information.

Thesis (MSc (Institute for Wine Biotechnology))--Stellenbosch University, 2010.
ENGLISH ABSTRACT: The process of winemaking involves a number of microorganisms, contributing both positively and negatively to the final product. Lactic acid bacteria (LAB) are present at all stages of vinification and therefore play a major role in the production of wine, especially red wine. LAB are responsible for malolactic fermentation (MLF), which can be desirable or unwanted depending on the style of wine. LAB can also be responsible for spoilage, and production of off flavours resulting in a decrease in the quality of the finished wine. Spoilage occurs if the wrong species are present at the wrong time and can also occur as a result of spontaneous MLF. It is therefore necessary to control the population of indigenous LAB present in the wine. Plantaricins are bacteriocins produced by Lactobacillus plantarum strains and have the potential to inhibit closely related strains that occupy the same ecological niche. This makes them promising for the control of LAB during the winemaking process. Inhibition of the indigenous LAB microflora could help to prevent the formation of undesirable off-flavours, as well as allowing for control over MLF. The use of plantaricin-producing starter cultures could also lead to a reduction in the amount of sulphur dioxide used in wine. The purpose of this study was to investigate the potential of L. plantarum strains isolated from wine to produce plantaricins under winemaking conditions. This potential was evaluated by investigating the expression of plantaricin genes under winemaking conditions. The first objective was to screen nineteen strains of L. plantarum isolated from South African red wines, as well as a commercial strain; for various genes responsible for the production of plantaricins, including structural, transport and regulatory genes. Results showed that the twenty strains contained at least 16 of the 24 genes (previously reported to be associated with the plantaricin locus for various L. plantarum strains) screened for. Only orfZ123 and orf345 genes yielded no positive results in any of the strains. The second objective was to sequence selected plantaricin genes (plnE, plnF, plnN, plnG and plnB) to determine the variation in nucleotide and amino acid sequences of these genes among the different wine L. plantarum isolates. High homology was found between the nucleotide sequences of the strains and none of the amino acid substitutions in the protein sequences occurred in conserved regions. The nucleotide sequence of plnN was identical in all but one of the strains and similarity of the plnB sequence ranged from 96% to 100%. Similarity of the plnG nucleotide sequence ranged from 99% to 100%. The plnE nucleotide sequence was identical in all but two strains and there were only two groups in terms of nucleotide sequence for plnF, with only two changes between the groups. The third objective was the evaluation of plantaricin production using plate assays mimicking certain wine parameters (pH and ethanol concentration). All twenty strains showed inhibitory activity to varying degrees against a panel of nine indicator microorganisms, including Enterococcus faecalis, Listeria monocytogenes and potential wine spoilage organisms, Lactobacillus spp, Pediococcus spp and Leuconostoc mesenteroides. Addition of 10% ethanol and a low pH of 3.5 decreased both the bacteriocin production as well as the spectrum of activity. Seven of the twenty strains, however, showed good bacteriocin activity under all conditions. The fourth objective was to investigate the expression of two plantaricin structural genes (plnEF and plnJK) and the transporter gene (plnG) under winemaking conditions. Two strains (R1122 and 113.1) were chosen, based on the results from the previous objectives, as starter cultures for MLF in synthetic wine media and Riesling wine. Low wine pH (3.2) and high wine pH (3.8) levels were investigated in conjunction with ethanol concentrations of 0%, 12% and 15%. All three of the genes were expressed to varying degrees depending on the fermentation condition. High ethanol and low pH generally decreased expression of the structural plantaricin genes. The influence on expression of the transporter gene was different, with low pH and presence of ethanol resulting in an increase in gene expression. The genes were also expressed in wine, although at a lower level relative to expression in the synthetic wine media. The presence of sensitive bacteria in the wine seemed to increase expression of the structural genes. Furthermore, expression of the mle gene responsible for MLF was investigated under the same winemaking conditions. Expression was shown to be inducible by malic acid, and negatively affected by the presence of ethanol but positively influenced by a lowering in pH from 3.8 to 3.2. This study confirms that plantaricin genes are expressed under winemaking conditions, which in turn indicates that the plantaricins could be produced under winemaking conditions. This confirms the potential use of these plantaricin-producing strains as starter cultures for MLF with the ability to inhibit indigenous LAB, however, presence of the plantaricin protein in wine still needs to be confirmed. It will also need to be established whether the protein is biologically active and not inhibited by wine-related factors.
AFRIKAANSE OPSOMMING: Die proses van wynmaak bevat 'n verskeidenheid mikroorganismes, wat postiewe en negatiewe bydrae kan lewer tot die finale produk. Melksuurbakterieë is teenwoordig by alle stadiums van wynmaak en speel 'n belangrike rol in die produksie van wyn. Melksuurbakterieë is verantwoordelik vir appelmelksuur gisting (AMG), wat gewens of ongewens kan wees, afhangende van die styl van die wyn. Melksuurbakterieë kan ook verantwoordelik wees vir bederf van wyn, asook die produksie van ongewenste geure wat bydrae tot ʼn toename in die kwaliteit van die wyn. Bederf van wyn kan gebeur as die verkeerde spesies voorkom op die verkeerde tyd en kan ook gebeur as ʼn gevolg van spontane AMG. Dit is dus nodig om die populasie van natuurlike melksuurbakterieë in wyn te beheer. Plantarisiene, geproduseer deur Lactobacillus plantarum wyn-isolate, het die potensiaal om naby verwante stamme se groei te inhibeer wat in dieselfde nis voorkom. Hierdie eienskap maak hul belowend vir die beheer van melksuurbakterieë se groei gedurende die wynmaakproses. Inhibering van die natuurlike mikroflora kan help om die vorming van ongewenste geure te verhoed, sowel as om AMG te beheer. Die gebruik van aanvangskulture, wat plantarisiene kan produseer, kan lei tot ’n vermindering in die gebruik van swaweldioksied in die wynindustrie. Die doel van hierdie studie was om die potensiaal van L. plantarum stamme, geïsoleer vanuit wyn, te ondersoek vir hul vermoë om plantaricins te produseer in toestande wat die wynmaakproses naboots. Die potensiaal was ondersoek deur te kyk na die uitdrukking van plantarisien-produserende gene onder wynmaak toestande. Die eerste objektief was om die 19 L. plantarum stamme, geïsoleer vanuit Suid-Afrikaanse rooi wyne, asook n kommersiele stam, te ondersoek vir die teenwoordigheid van verskeie gene wat verantwoordelik is vir die produksie van plantarisiene, sowel as strukturele, transporter en regulerende gene. Al twintig van hierdie stamme het ten minste 16 uit die 24 gene bevat waarvoor ondersoek was. OrfZ123 en orf345 het egter geen positiewe resultate opgelewer in enige van die stamme nie. Die tweede objektief was om die DNA-volgorde te bepaal van spesifieke gene (plnE, plnF, plnN, plnG, sowel as plnB) en sodoende die variasie in nukleotied en aminosuur volgorde van hierdie gene in die verskillende L. plantarum wyn-isolate te bepaal. Hoë vlakke van homologie was gevind en geen van die aminosuur veranderings het in behoue gebiede plaasgevind nie. Die nukleotied volgorde van plnN was identies in al die stamme, behalwe vir een, en die ooreenkomste tussen die plnB volgorde het varieër van 96% tot 100%. Die ooreenkomste tussen die plnG nukleotied volgorde het varieër van 99% to 100%. Die plnE nukleotied volgorde was identies in al die stamme, behalwe vir twee, en daar was net twee groepe in terme van nukleotied volgorde vir plnF, met net twee veranderinge tussen die groepe. Die derde objektief was om die vermoë van die stamme om plantaricins the produseer, deur gebruik te maak van plaat assays, onder verskillende wyntoestande te ondersoek. Die twinting stamme het verskillende vlakke van inhibering teenoor die nege toets-organismes getoon, wat Enterococcus faecalis, Listeria monocytogenes sowel as potensiele wyn bederf organismes, Lactobacillus spp, Pediococcus spp and Leuconostoc mesenteroides insluit. Die byvoeging van 10% etanol en ’n lae pH van 3.5, het beide bakteriosien produksie inhibeer, sowel as die spektrum van aktiwiteit verminder. Sewe van die stamme het egter steeds goeie aktiwiteit getoon onder al die kondisies wat getoets was. Die vierde objektief was om die uitdrukking van twee plantaricin strukturele gene (plnEF en plnJK), sowel as die transporter geen (plnG) onder wynmaak omstandighede te ondersoek. Twee stamme (R1122 en 113.1) was gekies as aanvangskulture vir AMG in sintesiese wyn media, sowel as Riesling wyn. Hierdie twee stamme was gekies op grond van die resultate wat van die vorige objektiewe verkry was. Lae wyn pH (3.2) en hoë wyn pH (3.8) was ondersoek in samewerking met verskillende etanol konsentrasies wat 0%, 12% en 15% etanol insluit. Al drie hierdie gene was uitgedruk teen verskillende vlakke, afhangende van die verskeie fermentasie kondisies. Hoë etanol en lae pH lei oor die algemeen tot ʼn toename in uitdrukking van die strukturele plantarisien gene. Die invloed op uitdrukking van die transporter geen was verskillend, want lae pH en die teenwoordigheid van etanol het gelei tot ʼn verhoging in geen uitdrukking. Die gene was uitegdruk in wyn, maar was teen laer vlakke relatief tot uitdrukking in die sintetiese wyn media. Dit blyk dat die teenwoordigheid van sensitiewe bakterieë in die wyn tot ‘n hoër uitdrukking van die strukturele gene lei. Die uitdrukking van die mle geen, verantwoordelik vir AMG, was ook onder dieselfde wynmaak kondisies ondersoek. Die uitdrukking was geïnduseer deur appelsuur, negatief beïnvloed deur die teenwoordigheid van etanol, maar positief beïnvloed deur ’n verlaging in pH van 3.8 tot 3.2. Hierdie studie toon dat plantaricin gene uitegedruk word onder wynmaak toestande en dat plantaricins moontlik onder hierdie toestande geproduseer kan word. Die potensiaal van hierdie stamme word getoon om as aanvangskulture gebruik te word vir AMG, om sodoende die groei van natuurlike melksuur bakterieë te inhibeer. Die teenwoordigheid van die plantarisien peptied in die wyn moet egter nog bewys word. Daar sal ook vasgestel moet word of die peptied biologies aktief is en nie deur wynverwante faktore geïnhibeer word nie.

Thesis (MscAgric (Viticulture and Oenology))--Stellenbosch University, 2008.
Over the years, different techniques have been used to legally reduce the ethanol content of wines. Several physical processes are available for producing wines with less alcohol. Despite their efficacy, these treatments have a capital and operational cost influence. They can also affect the concentration of other wine components. On the other hand, vast amount of research has been conducted through genetic modification of wine yeast strains in order to reduce the ethanol yield of Saccharomyces cerevisiae by diverting sugar metabolism towards various byproducts. However, genetically modified yeasts are not currently accepted in most wine industries worldwide, including South Africa. Therefore, other approaches need to be envisaged. Commercial enzymes are commonly added during winemaking. Most enzymes essential for vinification naturally occur in grapes, but are inefficient under pH and sulphur levels associated with winemaking. Enzymes of fungal origin are resistant to such conditions. The most widely used commercial enzymes include pectinases, hemicellulases, glucanases and glycosidases. With the exception of glucanases, produced by Trichoderma harzianium, all the other enzymes are produced by Aspergillus niger. In this study, the possibility of using Gluzyme Mono® 10.000 BG (Gluzyme) (Novozymes, South Africa) to reduce the glucose content of synthetic grape must and grape must before fermentation in order to produce wine with a reduced alcohol content was investigated. Gluzyme is a glucose oxidase preparation from Aspergillus oryzae, currently being used in the baking industry. Glucose oxidase catalyses the oxidation of glucose to gluconic acid and hydrogen peroxide in the presence of molecular oxygen. Gluzyme was initially used in synthetic grape must where different enzyme concentrations and factors influencing its activity were investigated for its use in winemaking. The results showed that up to 0.5% v/v less alcohol were obtained using an enzyme concentration of 20 kU compared to the control. This reduction in alcohol was increased to 1 and 1.3% v/v alcohol at pH 3.5 and pH 5.5 respectively in aerated synthetic grape must using 30 kU enzyme. Secondly, Gluzyme trials were carried out using Pinotage grape must. Gluzyme treated wines after fermentation contained 0.68% v/v less alcohol than the control samples at 30 kU enzyme. Colour and volatile flavour compounds of treated wine did not differ significantly from the untreated samples. Lower free anthocyanin and total phenol concentrations in treated than control samples were observed, possibly due to the hydrogen peroxide oxidation which could have led to polymerisation. The present study has clearly demonstrated that Gluzyme may be used in winemaking to produce reduced-alcohol wine without affecting its colour and aroma compounds. The enzyme in its current form is however, not ideal for winemaking; other forms such as liquid or powder form should be considered if the enzyme is to be used under winemaking conditions. Future work should focus on evaluating the potential new form of the enzyme and studying the effects of Gluzyme in various grape must in semi-industrial scale. A tasting panel should also evaluate its impact on the organoleptic properties and the overall quality of the resulting wines.

Alcoholic fermentation is a process mainly characterised by several factors that induce yeast stress response (low pH, high osmotic pressure, low nitrogen content, etc). Thus, stress response is essential to yeast in order to assure its survival, adaptation and growth, in both natural habitats and industrial conditions such as winemaking. One of the main features to optimise and improve alcoholic fermentation is the establishment of metabolic and physiological changes by the yeast just after must inoculation. In this early phase, yeast must quickly change its metabolism to achieve maximum advantage in the new growth medium. Oenological industry uses selected active dry wine yeast (ADWY) to inoculate the musts in order to get a better control over the fermentation process. Those dry yeasts have to be rehydrated before must inoculation. Therefore, yeast rehydration is the first step to ensure healthy cells and a good fermentation performance. The knowledge of the early yeast metabolic responses, from a biochemical and physiological point of view, were the main objectives of this thesis. The studied objectives were:

Analysis of trehalose and glycogen metabolism (reserve carbohydrates) in a commercial wine yeast strain, considering these carbohydrates markers of stress response. Study of their metabolism in winemaking conditions, taking into account the fermentation temperature (low 13ºC and control 25ºC), nitrogen content (low 60 mg/l, control 300 mg/l and high 1200 mg/l) and the ADWY rehydration and pre-adaptation.

Determination of early transcriptional responses of yeast just after must inoculation. It was considered the presence of glucose and fructose, the osmotic shock and the yeast metabolic activation, including the presence of the drug Cycloheximide, which is an inhibitor of protein synthesis.

Characterisation of the standard protocol of ADWY rehydration in an oenological context, which is rehydrate in warm water (37ºC) during 30 minutes.

Low fermentation temperatures affected fermentation kinetics, but not induced any additional stress response. In fact, high levels of trehalose were accumulated at control temperature than at 13ºC. In industrial conditions, after a period of pre-adaptation before inoculation, carbohydrates were completely depleted once yeasts were inoculated into the must. Their synthesis started simultaneously with a change in the phase of growth, from exponential to stationary, coinciding with nitrogen depletion.
We also studied rehydration and characterised the early response to synthetic must but also to relevant conditions that ADWY must cope after inoculation (osmotic shock, presence of carbon sources). Glycogen content did not presented any change. However, trehalose was early mobilised in those media capable to ensure yeast growth.
The effect of nitrogen availability upon trehalose metabolism was also studied. Neither glucose nor nitrogen exhaustion were involved in the regulation of trehalose metabolism. TPS1 (gene which codifies for trehalose-6-phosphate synthase) was induced just before trehalose accumulation, simultaneously with growth arrest. Microarray technique was used to determine whole gene expression after rehydration and in the same conditions previously studied. We can conclude that 30 minutes of rehydration in water is enough for the yeast to fully recover and that longer times in this medium are detrimental. The yeast transcriptional switch is the presence of fermentable sugars, and this is mostly related to ribosome and protein synthesis, glycolysis and ethanol synthesis.
La fermentació alcohòlica és un procés bàsicament caracteritzat per una sèrie de factors que indueixen estrès al llevat, el microorganisme responsable de la seva consecució. La resposta a estrès per part del llevat és essencial per a la seva supervivència, adaptació i creixement, tant en medis naturals com en processos industrials (enologia). Una de les principals característiques per a l'optimització de la fermentació alcohòlica és l'establiment de canvis metabòlics i fisiològics del llevat just després de la inoculació en el most. És en aquesta fase inicial quan el llevat ha de canviar ràpidament el seu metabolisme per tal d'adquirir el màxim d'avantatge en el nou medi de creixement. La indústria enològica disposa de llevats secs actius (LSA) seleccionats que s'inoculen al most per tal d'assolir un millor control sobre el procés fermentatiu. Aquests llevats secs requereixen d'una rehidratació prèvia a la inoculació en el most. La rehidratació és el primer pas per tal d'assegurar el bon estat cel.lular i una bona fermentació alcohòlica. El coneixement de les respostes metabòliques inicials del llevat des d'un punt de vista bioquímic i fisiològic foren els objectius fonamentals d'aquest treball. Els objectius van ésser:

- Anàlisi del metabolisme de trehalosa i glicogen (carbohidrats de reserva) en una soca de llevat comercial, com a indicadors de resposta a estrès. Estudi del metabolisme en condicions víniques, considerant com a variables la temperatura de fermentació (baixa, 13ºC i control, 25ºC), contingut en nitrogen (baix 60 mg/l, control 300 mg i elevat 1200 mg/l) i la rehidratació i preadaptació del LSA.
- Determinació de les respostes transcripcionals inicials del llevat immediatament després de la seva inoculació en el most. Es va considerar la presència de glucosa i fructosa, el shock osmòtic i l'activació metabòlica del llevat, incloent la presència de cicloheximida, un inhibidor de la síntesi proteica.
- Caracterització del protocol estàndard de rehidratació del llevat dins el context enològic, que és la utilització d'aigua a 37-40ºC durant 30 minuts.

Les baixes temperatures de fermentació van incidir sobre la cinètica fermentativa, però no sobre una resposta a estrès. De fet, es va trobar major acumulació de trehalosa a temperatura control que a 13ºC. En condicions industrials, després d'un període d'adaptació previ a la inoculació (peu de cuba), els nivells de carbohidrats van ser nuls. La seva síntesi es va produir al canvi de fase exponencial a estacionària, coincidint amb l'esgotament de nitrogen. Es va estudiar la rehidratació i permanença en diferents medis (aigua, glucosa/fructosa, most sintètic i sorbitol). La concentració intracel.lular en glicogen no presentà cap modificació. Però la trehalosa es va metabolitzar en les fases inicials, en aquells medis favorables per al creixement del llevat.

Es va estudiar l'efecte de la disponibilitat de nitrogen sobre el metabolisme de la trehalosa. Independentment del contingut nitrogenat, el seu metabolisme no es va veure modificat. TPS1 (gen que codifica trehalosa-6-fosfat sintasa) es va induir just abans de la acumulació de trehalosa, coincidint amb l'aturada del creixement cel.lular. Mitjançant la tècnica dels "microarrays" es va determinar l'expressió gènica global del llevat després de rehidratar i romandre en els medis anteriors. Podem concloure que el temps de rehidratació utilitzat en enologia assegura la total recuperació de LSA. Temps més llargs afectaren negativament la fisiologia del llevat, reduint significativament la seva vitalitat. Les modificacions transcripcionals al most foren degudes bàsicament a la presència de glucosa i fonts nitrogenades, induint la síntesi proteica, glucòlisi i producció d'etanol.

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The production of wine globally has increased over the past years, increasing the volume of water used and wastewater generated for every litre of wine produced. In the past, the small volumes of winery wastewater that were produced by wineries had little effect on the immediate environment. However, with the increasing wine production all around the world, winery wastewater is a rising concern for the contamination of soil and subsurface flow. In order to fully understand the impacts of winery wastewater, it is important to establish the volumes and chemical characteristics of the wastewater, before considering possible treatments. The first aim of this study was to determine the influence of certain winemaking practices on the water usage. Two wineries in the Stellenbosch Winelands District were monitored during two harvests and one post-harvest season. It was evident through this study that water plays a vital role during the production of wine and that water is needed at virtually all the winemaking steps. However, the volume of clean water needed differs immensely during the course of the production process. It was noticed that throughout the harvest period at both wineries the clean water demand was highest and decreased during the course of the post-harvest period and steadily increased again towards the end of the year. The harvest period contributes between 30 and 40% of the yearly water usage at the respective wineries. It was also noticed that certain winemaking practices including filtering with a bulk filter, washing of barrels and bottling contributes heavily to the water usage throughout the year. Activities that increase water usage during harvest include the washing of the press and processing a combination of red and white grapes on the same day. Furthermore, it was identified that one of the wineries used a smaller volume of water on a daily basis and per tonnage during harvest than the other, indicating that the cleaner production strategy established 10 years earlier has a positive impact on their water usage. The second aim of this study was to monitor the raw and treated winery wastewater from the two wineries during a period of 15 months, including two harvests and one post-harvest season. This was done to investigate the characteristics of the raw and treated wastewater. Firstly, to determine the impact of the different winemaking practices on the chemical composition of the wastewater and secondly, to determine the efficiency of the existing constructed wetlands on the wastewater and the characteristics of the treated wastewater. From this study it was possible to make two main observations concerning the chemical oxygen demand (COD) concentrations of the two wineries. Primarily, it was observed there were variations in the raw wastewater characteristics of the two wineries and above all, that both wineries showed a decrease in the COD of the raw wastewater produced. Not only did the decrease in the raw wastewater COD over this period show promising results when a cleaner production plan is established and managed it also seems to show a decrease in the volumes of water used by the respective wineries and increase in quality.
AFRIKAANSE OPSOMMING: Gedurende die afgelope paar jaar het wynproduksie wêreldwyd toegeneem en as gevolg hiervan toenemende hoeveelhede water gebruik en afvalwater gegenereer. In die verlede het die klein volumes kelderafvalwater wat deur wynkelders geproduseer is min effek op die onmiddelike omgewing gehad, maar gegewe die toenemende produksie van wyn regoor die wêreld is daar groeiende kommer oor die besoedeling van gronde en ondergrondse vloei deur kelderafvalwater. Dit is belangrik om die volumes en chemiese eienskappe van die afvalwater te bepaal om die impak van die water ten volle te verstaan, voordat moontlike behandelings oorweeg word Die eerste doel van hierdie studie was om te bepaal hoe sekere wynmaakpraktyke watergebruik beïnvloed. Twee wynkelders in die Stellenbosch Wynland Distrik is gedurende twee parsseisoene en een na-pars seisoen gemonitor. Hierdeur het dit duidelik geword dat water ‘n noodsaaklike rol speel in wynproduksie en benodig word vir feitlik alle stappe in die wynmaakproses. Die volume skoon water wat benodig word verskil wel noemenswaardig tydens die produksieproses. Die gebruik van skoon water van beide kelders was hoog tydens die parsseisoen, het afgeneem gedurende die loop van die na-pars periode en het geleidelik weer toegeneem teen die einde van die jaar. Die parsseisoen dra tussen 30 en 40% by tot die jaarlikse waterverbruik van die onderskeie kelders. Dit is ook opgemerk dat sekere wynmaakpraktyke, insluitend filtrasie met ‘n grootmaat filter, die was van vate en bottelering, grootliks bydrae tot die waterverbruik deur die loop van die jaar. Aktiwiteite wat waterverbruik tydens parstyd verhoog sluit in die gebruik van die pers en die verwerking van ‘n kombinasie van rooi en wit druiwe op dieselfde dag. Daar is ook vasgestel dat een van die wynkelders tydens parstyd ‘n kleiner volume water gebruik op ‘n daaglikse basis asook per tonnemaat wat daarop dui dat die “skoner” produksie strategie wat dié kelder 10 jaar gelede gevestig het wel ‘n positiewe impak op waterverbruik het. Die tweede doel van hierdie studie was om die onbehandelde en behandelde afvalwater van hierdie twee wynkelders te monitor oor 'n tydperk van 15 maande, wat twee paste en een na-pars seisoen insluit. Dit is gedoen om die impak van verskillende wynmaakpraktyke op die chemiese samestelling van die afvalwater te ondersoek asook om die doeltreffendheid van bestaande kunsmatige vleilande in terme van afvalwaterbehandeling te bepaal en die eienskappe van die behandelde afvalwater te ondersoek. Gevolglik is twee belangrike waarnemings oor die chemiese suurstof behoefte (CSB) konsentrasie van die twee wynkelders gemaak. Variasies in die onbehandelde afvalwater eienskappe is waargeneem by beide wynkelders en daar was ‘n afname in CSB van die onbehandelde afvalwater by beide wynkelders. Die afname in CSB van die onbehandelde afvalwater oor hierdie tydperk is belowend en dit blyk dat wanneer ‘n “skoner” produksie plan opgestel en bestuur word dit wel ‘n afname in waterverbruik en verhoog in kwaliteit by die kelders tot gevolg het.

Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2011.
Includes bibliography.
ENGLISH ABSTRACT: Grape and wine phenols consist of flavanols which is the building blocks for tannins. These building blocks are called monomers which consist of catechins, epicatechins, epigallocatechins and epicatechin-gallate. Tannin is important in wine as it contributes to bitterness, mouth feel (astringency) and maturation potential of the wine. Futhermore it has a health benefit as an antioxidant. Anthocyanins are responsible for the colour of red wine. The anthocyanins combine with tannins to form stable polymeric pigments. Due to the importance of tannins and anthocyanins in wine, it is imperitative that different winemaking techniques are used to extract as much of these components as possible and that the analysis is done quickly and accurately. The aim of this study was to evaluate different winemaking techniques and their extraction of tannins and anthocyanins into the wine. Too much tannin extraction can have a negative effect on the sensory quality of the wine. Therefore a second aim was to evaluate the mouth feel properties of a Shiraz wine. A third aim was to compare the two tannin precipitation methods in terms of time efficiency, repeatability and the ease of practice. To investigate the amount of tannin concentration extracted by different winemaking techniques, two cultivars (Cabernet Sauvignon and Shiraz) were used. These treatments included the addition of an enzyme during fermentation [E], cold maceration [CM], post maceration [PM] and the combination of cold and post maceration [CM+PM]. The grapes were harvested in two different climatic areas during the 2008 and 2009 vintages. The two climatic areas were classified according to the Winkler scale as a III (Morgenster) and a IV (Plaisir de Merle). The grapes were harvested at two different ripeness levels in order to evaluate the effect of the different winemaking processes on the extraction of tannins and anthocyanins. One harvest was before (LB) and the other after (HB) the commercial harvest. The results of this study showed significant differences in the phenolic composition of the wines. It was found that the warmer area showed higher tannin concentrations than the cooler area for both cultivars. In the 2008 Cabernet Sauvignon the CM extracted higher concentrations of tannin from the cooler area at both ripeness levels. In the warmer area, CM extracted the highest tannin concentration HB, but the CM+PM extracted the highest tannin concentration from Cabernet Sauvignon at the LB and CM at the HB of the warmer area. In 2009 the PM extracted the highest concentration of tannin at the lower ripeness level, while the E treatment extracted the highest concentration from the warmer area. In the cooler area the CM+PM extracted the highest concentration of tannin at a lower ripeness level, while there were no siginicant differences between the different treatments at the higher ripeness level. The highest anthocyanin concentration was found in the cooler area. The CM treatment was found to have no effect on anthocyanin extraction. Different methods are available to quantify the tannin concentration in wine. Two of the most popular tannin analytical methods are the bovine serum albumin (BSA) and the methyl cellulose precipitable tannin (MCP) methods. The BSA method is a very complex method which uses at least 3 times more reagents than the MCP method. The MCP method only analyzes tannins, while the BSA method analyzes tannins, monomeric pigments (MP), small polymeric pigments (SPP) and large polymeric pigments (LPP). In this study a good correlation was found between the two tannin precipitation methods (R2 – 0.88). There is controversy regarding the variability of these methods. Some scientists found that the two methods show a good correlation with HPLC, while others found that there was no such correlation between the precipitation methods and the HPLC. The MCP method had a practical advantage as it could be performed in half the time required for the BSA method. This has a significant impact in scenarios where a high sample throughput is required although it only measures total tannin. The phenolic composition and mouth feel of the wine was strongly influenced by the climatic area. In the warmer area the effect of tannin concentration on mouth feel was much less than in the cooler area. The wine made of riper grapes, was more grippy, bitter and numbing than the wines made from greener grapes. The E treatment was especially associated with a dry, grippy sensation.
AFRIKAANSE OPSOMMING: Druif en wyn fenole bestaan uit flavanole wat weer die boublokke is van tanniene. Hierdie boublokke, wat bekend staan as monomere, betsaan uit katesjiene, epikatesjiene, epigallokatesjiene an epikatesjien-gallaat. Tanniene is belangrik in wyn aangesien dit bydra tot bitterheid, mondgevoel (vrankheid) asook die verouderingspotensiaal van wyn. As antioksidante hou dit ook gesondheidsvoordele in. Antosianiene dra by tot die kleur van rooiwyn. Antosianiene kombineer met tanniene om meer stabiele polimeriese pigmente te vorm. As gevolg van die belangrikheid van tanniene en antosianiene is dit van uiterse belang dat verskillende wynmaak tegnieke gebruik word om ekstraksie in die wyn te bevoordeel en dat die analitiese metode so vinnig en akkuraat as moontlik gedoen word. Die eerste doel van hierdie studie was om die ekstraksie van tanniene en antosianiene deur middel van verskillende wynmaak tegnieke te evalueer. Te veel tanniene in die wyn kan negatiewe sensoriese kwaliteit tot gevolg het. Daarom is die tweede doel om die sensoriese kwaliteit van Shiraz wyn te evalueer. Die derde doel van hierdie studie was die twee tannien presipitasie metodes met mekaar te vergelyk in terme van die moeilikheidsgraad van die metode, tyd doeltreffendheid en herhaalbaarheid. Verskillende wynmaak tegnieke (ensiem byvoegings [E], koue maserasie [CM], verlengde dopkontak [PM] en ‘n kombinasie van koue maserasie en verlengde dopkontak [CM+PM]) is vergelyk ten opsigte van tannien en antiosianien ekstraksie. In 2008 en 2009 is twee kultivars (Cabernet Sauvignon en Shiraz) in twee verskillende klimatologiese areas gepars. Hierdie areas is geklassifiseer in die Winklerskaal as ‘n IV (Plaisir de Merle) en ‘n III (Morgenster). Om die effek van die verskillende wynmaak tegnieke op die ekstraksie van antosianiene en tanniene te vergelyk, is hierdie twee kultivars by twee verskillende rypheidsgrade geoes. Die eerste oes was net voor kommersiële oes (LB) en die tweede oes het net na kommersiële oes (HB) plaasgevind. Die 2009 Shiraz wyn is organolepties beoordeel om die effek van die verskillende wynmaak tegnieke op die wyn se mondgevoel te vergelyk. Die resultate van hierdie studie toon beduidende verskille in die fenoliese samestelling van die wyne. Dit is gevind dat die warmer area hoër tannien konsentrasies het as die koeler area. In 2008 het die CM+PM die meeste tanniene uit die Cabernet Sauvignon geëkstraheer by LB en die CM by HB in die warmer area. Die CM het in die koeler area meer tanniene geëkstraheer by beide die LB en HB rypheidsgrade. In 2009 het PM die meeste tanniene geëkstraheer by LB terwyl E die meeste tanniene geëkstraheer in die warmer area. In die koeler area het CM+PM die meeste tanniene geëkstraheer, terwyl geen van die behandelings ‘n effek gehad het by HB. Die meeste antosianien konsentrasie was in die koeler area gevind as in die warmer area. In beide 2008 (LB en HB) en 2009 (LB) het CM die meeste antosianiene geëkstraheer, terwyl geen behandeling ‘n effek gehad het by HB. Twee van die mees populêre tannien analitiese metodes is die BSA (bovine serum albumien) en die MCP (metielsellulose presipitasie) metodes. Die BSA metode is ‘n baie meer ingewikkelde metode waarvoor drie keer meer reagense gebruik word as vir die MCP metode. Maar waar die MCP net tanniene ontleed, ontleed die BSA metode tanniene, monomere (MP), klein polimeriese pigmente (SPP) en groot polimeriese pigmente (LPP). Dit help indien daar gekyk wil word na die evolusie van polimeriese pigmente. In hierdie studie is bevind dat daar ‘n redelike korrelasie (R2 – 0.88) tussen die BSA en MCP metode bestaan. Die herhaalbaarheid van die metodes het redelike kontroversie veroorsaak, waar sommige navorsers bevind het dat die BSA metode nie so herhaalbaar is soos eers bevind is nie. Die MCP metode het ’n praktiese voordeel aangesien dit in die helfde van die tyd van die BSA metode uitgevoer kan word. Dit het ‘n groot impak indien ‘n groot hoeveelheid monsters ontleed moet word. Die fenoliese samestelling en mondgevoel word sterk beïnvloed deur die klimatologiese area. In die warmer area was die effek van tannien konsentrasie op mondgevoel kleiner as in die koeler area. Die wyn van ryper druiwe het meer harder, verdowingseffek en bitter nasmaak gehad as by die wyn van groener druiwe. Die ensiem behandeling was meer geassossieerd met droë mond gevoel.

Aroma is one of the most important attributes involved in wine quality. Current trend in winemaking consists of producing wines with different aroma nuances to offer variety of wines to a developing market. Several studies have demonstrated that low temperature fermentations favours aroma synthesis and retention. In this background, new wine yeasts able to perform fermentation at low temperatures improving wine aroma while maintaining good fermentation rates are necessary. This doctoral thesis explores the oenological traits of different Saccharomyces species and hybrids relevant for present-day wine industry, especially regarding aroma production, as well as the molecular bases underneath. This exploration has been possible using different biochemical, analytical chemistry and molecular techniques to perform enzymatic activity detection, aroma profile determination and transcriptome analysis in wine fermentations. Through this doctoral thesis the abilities of different Saccharomyces species and hybrids regarding primary aroma release and secondary aroma production, especially at low temperatures, has been elucidated in order to know the different possibilities that these yeasts offer to create new wines with different aromatic nuances. One of the general conclusions of this doctoral thesis is that production and release of aromas in winemaking depends on the strain carrying out the fermentation process. Nevertheless, sometimes there was a species tendency. On the other hand, the fact that fermentation temperature affects aroma synthesis but not always in the direction to aroma increase has been demonstrated.
Gamero Lluna, A. (2011). Study of the production and release of aromas during winemaking carried out by different Saccharomyces species and hybrids [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/10741
Palancia

This thesis shows the results obtained from adding bentonite at different stages of the alcoholic fermentation in protein stability and reducing the bentonite required to reach stability. Results reflect the effect of this practice on alcoholic fermentation, chemical composition of wines, protein content and profile, aromatic profile and foam quality. The study was carried at pilot and industrial scale, with several grape varieties, in different geographical areas and during three vintages. The advantage of using bentonite during alcoholic fermentation was established, especially in moderate doses, making the addition from the middle of fermentation, obtaining more stable wines with less bentonite. Wines that were stabilized by bentonite treatment during fermentation were the best sensorial evaluated. Reproducibility between scales was confirmed for almost every parameter checked. Protein fractions and bentonite stabilizing dose for the different white wines was also identified and correlated. A commonly used technique was improved, achieving better quality wines.
En esta tesis se presentan los resultados de adicionar bentonita en diferentes etapas de la fermentación alcohólica en la estabilidad proteica y en la reducción de la dosis estabilizante de bentonita. Se aprecia el efecto en la fermentación, la composición química de los vinos, el contenido y perfil proteico, el perfil aromático y la calidad de la espuma. El estudio fue realizado a escala piloto e industrial, con diferentes variedades de uva, en distintas zonas geográficas y durante tres vendimias. Se estableció la ventaja de usar bentonita durante la fermentación, especialmente en dosis moderadas a partir de la mitad de la fermentación, obteniéndose vinos más estables con menos bentonita y mejor evaluados sensorialmente. Se confirmó la reproductibilidad entre escalas para la mayoría de los parámetros evaluados. Se identificaron y correlacionaron fracciones proteicas con dosis estabilizante de bentonita. Así se mejoró una técnica comúnmente usada para obtener vinos de mejor calidad.

Includes bibliographies.
The central hypotheses advanced in the dissertation are: 1. Wine farmers in the Western Cape have, since the 1970s; been increasingly changing the form of labour control on their farms from co-ercive to co-optive techniques. 2. The Rural Foundation has played a key role in promoting and facilitating these changes to co-optive methods of labour control. 3. The changes to co-optive forms of labour control have resulted in corresponding changes in the form of paternalism that has characterised the relations of production in the Western Cape for the past three centuries. 4. Whilst the change to co-optive managerial techniques has improved working and living conditions for farmworkers, it has not necessarily reduced the dependency of farmworkers on the farmers, nor empowered workers. 5. Farmworkers have themselves internalised the ideology of 'enlightened' paternalism, with this ideology being fundamental in structuring their work-place behaviour. Trade unionists need to recognise this, and strategise accordingly. The empirical data that is used both to verify the fore-mentioned theoretical statements, and to provide information used in the construction of these statements, was gathered by means of interviews. Interviews were conducted with nine farmers/farm managers and 25 farmworkers from wine farms in Koelenhof, two members of both the Rural Foundation and the Food and Allied Workers Union and an organiser for the National Council of Trade Union's National Union of Wine, Spirit and Allied Workers. This empirical information is integrated into a conceptual method that draws from both the structuralist and social historian perspectives in agrarian social theory. In this sense, the discussion in both abstract and theoretical, and descriptive. Furthermore, the discussion is, at times, prescriptive, arguing that trade unions should adopt particular tactics in their attempts to defend and advance the interests of farmworkers in South Africa.

Thesis (MSc)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: This study focused on the potential of comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOF-MS) for the improved analysis of volatile wine constituents. Solid phase microextraction (SPME) in combination with GC×GC-TOF-MS was successfully used for the detailed investigation of the impact of three commercial Oenococcus oeni lactic acid bacteria (LAB) strains on the volatile composition of Pinotage wines subjected to malolactic fermentation (MLF). Due to increased separation power and enhanced sensitivity obtained by using two orthogonal separations coupled with the structural information provided by deconvoluted TOF-MS spectra, GC×GC-TOF-MS allowed for the identification and semi-quantitative analysis of much larger numbers of compounds compared to previous studies applying one-dimensional gas chromatography. The combination of univariate and multivariate statistical assessment was used as a powerful tool for data interpretation. The obtained results contribute significantly to the understanding of the impact of MLF on the volatile composition of Pinotage wine Some compounds have been linked to MLF for the first time. Moreover, the impact of these commercial starter cultures on the composition of volatile sulfur and nitrogen compounds in the same wines was studied by one-dimensional gas chromatographic methods with headspace injection and solid supported liquid-liquid extraction together with sulfur selective detection and tandem mass spectrometry. This study demonstrated also for the time, the impact of MLF on the composition of volatile sulfur and nitrogen compounds in Pinotage wine. GC×GC-TOF-MS was further used for the evaluation of the suitability of a new phase for stir bar sorptive extraction (SBSE) analysis of wine volatiles. Despite instrumental complications, beneficial extraction properties of the new stir bar phase for especially more polar compounds could be demonstrated. In addition, the extraction ability of this novel phase was evaluated for the analysis of selected thiazoles in wine using heart-cutting two dimensional gas chromatography in combination with nitrogen selective detection. Advantageous extraction performance of the new stir bar phase compared to a conventional polydimethylsiloxane (PDMS) phase for the determined thiazoles was demonstrated.
AFRIKAANSE OPSOMMING: Hierdie studie het gefokus daarop om die potensiaal van omvattende tweedimensionele gaschromatografie gekombineer met vlugtyd massaspektrometrie (GC×GC-TOF-MS) vir die verbeterde analise van vlugtige wynkomponente te ondersoek. Soliede fase mikro-ekstraksie (SPME) in kombinasie met GC×GC TOF MS is met sukses aangewend vir ‘n ondersoek na die impak van drie kommersiële Oenococcus oeni melksuur bakteria (LAB) rasse op die samestelling van die vlugtige fraksie van Pinotage wyne wat appelmelksuurgisting (AMG) ondergaan het. As gevolg van die verbeterde skeidingsvermoë en die verhoogte sensitiwiteit wat verkry word deur twee ortogonale skeidings te kombineer, tesame met die inligting aangaande die molekulêre struktuur wat die die gedekonvoleerde TOF massaspektra verskaf, maak GC×GC-TOF-MS die identifikasie en semi-kwantitatiewe analise van aansienlik meer komponente, in vergelyking met die gebruik van een-dimensionele gaschromatografie, moontlik. Die kombinasie van monoveranderlike asook multiveranderlike statistiese evaluering is gebruik as ‘n kragtige tegniek vir data interpretasie. Die resultate wat verkry is dra tot ‘n groot mate by tot die ontrafeling en begrip aangaande die impak wat AMG op die samestelling van vlugtige komponente in Pinotage wyn het. Daar word ook vir die eerste keer aangetoon dat somminge komponente verband te hou met AMG. Aanvullend hiertoe is die impak wat hierdie kommersiële kulture (wat gebruik word om fermentasie te inisieer) op die voorkoms van swawel en stikstof bevattende vlugtige komponente het bestudeer deur gebruik te maak van een-dimensionele gaschromatografiese metodes met ‘headspace’ inspuiting en vloeistof-voeistof ekstraksie tesame met swawel en stikstof selektiewe deteksie en tandem massaspektrometrie. Hierdie ondersoek werp lig, ook vir die eerste keer, op die samestelling van vlugtige swawel en stikstof bevattende komponente in Pinotage wyn. GC×GC-TOF-MS is ook gebruik vir die evalueering van die toepaslikheid van ‘n nuwe stasionêre fase vir gebruik met roerstaaf sorptiewe ekstraksie (SBSE) vir die analisering van vlugtige komponente in wyn. Ten spyte van instrumentele komplikasies, is die voordele wat hierdie nuwe fase vir die ekstraksie van vernaamlik meer polêre komponete aangetoon. Vervolgens is die ekstraksievermoë van hierdie nuwe fase vir die analise van sekere tiasole in wyn met ‘heart-cutting’ twedimensionaly gaschromatografie in kombinasie met stikstof-selektiewe deteksie gedemonstreer. Verbeterde ekstraksie van die nuwe roerstaaf fase vir die analise van tiasole, in vergelyking met ‘n tradisionele polydimethylsiloxane (PDMS) fase is voorts aangetoon.

A ocratoxina (OTA) é uma micotoxina que possui propriedades nefrotóxicas, hepatotóxicas, teratogênicas e carcinogênicas. No Brasil, o limite máximo permitido de OTA em vinhos foi estabelecido em 2011 e é 2 μg/L. A ocorrência desta toxina em vinhos está relacionada principalmente à presença de fungos do gênero Aspergillus nas uvas usadas para a vinificação. Deste modo, o objetivo deste estudo foi verificar a influência das etapas de elaboração de vinho Cabernet Sauvignon sobre os níveis de OTA, através de dois diferentes experimentos: (A) vinho elaborado a partir de uvas inoculadas com fungo ocratoxigênico e (B) vinho elaborado com uvas naturalmente contaminadas com OTA. Para os dois experimentos, amostras das etapas mosto, fermentação/maceração, descuba, pós-fermentação, trasfega e maturação foram coletadas em triplicata, durante um período de 5 meses. A OTA foi detectada através da técnica de cromatografia líquida de alta eficiência com detector de fluorescência (CLAE-FL) e o limite de detecção e quantificação foi de 0,06 μg/L e 0,6 μg/L, respectivamente. Durante a vinificação, as etapas que apresentaram maior percentual de redução da toxina foram descuba, pós-fermentação e trasfega. Reduções significativas nos níveis de OTA foram observadas após a conclusão da vinificação. No vinho elaborado com uvas inoculadas com fungo ocratoxigênico observou-se uma redução de 92,6%. Valor similar (92%) foi verificado no vinho produzido com uvas naturalmente contaminadas por OTA. Considerando todo o processo de vinificação, pode-se sugerir que a diminuição dos níveis de OTA foi observada principalmente, devido à adsorção da toxina à parede celular das leveduras. Além disso, a adsorção da toxina aos sólidos em suspensão presentes no vinho durante a elaboração pode ter ocorrido.
The ochratoxin A (OTA) is a mycotoxin with nephrotoxic, hepatotoxic, teratogenic and carcinogenic properties. In Brazil, the permitted maximum limits for the OTA in wines was established in 2011 and is 2 μg/L. The occurence of this toxin in wines is due mainly for presence of fungi from Aspergillus genera in grapes used for winemaking. In this way, the aim of this study was to check the influence of stages of the winemaking process of Cabernet Sauvignon grape on the OTA levels through two different experiments: (A) wine made from grapes inoculated with ochratoxigenic fungi and (B) wine made from grapes naturally contaminated with OTA. For the two experiments, samples of must, fermentation/maceration, drawn-off wine, after fermentation, racking and maturation stages were collected in triplicate, during 5 months. The OTA was detected using high-performance liquid chromatography with fluorecence detector (HPLC-FL) and the limit of detection and limit of quantitation were 0.06 and 0.6 μg/L, respectively. During the winemaking, the stages that show higher toxin reduction were drawn-off wine, after alcoholic fermentation and racking. Significant reductions in OTA levels were observed when winemaking was finished. A reduction of 92.6% was observed in wine made from grapes inoculated with ochratoxigenic fungi. Similar value (92%) was verified in wine made from grapes naturally contaminated with OTA. Considering all winemaking process, we may suggest that the decreasing of OTA levels was observed mainly due to adsorption of the toxin in cell wall of yeast. Furthermore, the adsorption of the toxin in suspended solids present in wine during the winemaking may be occurred.

Portugal apresenta um excedente comercial no que diz respeito ao vinho, sendo a internacionalização bastante relevante na estratégia das empresas do setor vitivinícola. Com base numa abordagem mista, analisou-se o processo de internacionalização e de marketing mix internacional do Grupo Parras, onde se encontrou a exportação direta como modo predominante de entrada nos diferentes mercados internacionais. Foi possível, agrupar as motivações para a internacionalização em pró-ativas e reativas, e identificar a experiência internacional e a flexibilidade como competências fundamentais à internacionalização. O Grupo Parras não considera relevantes as barreiras à internacionalização, e adota uma estratégia de marketing mix internacional idêntica para os diversos mercados, baseada nos custos e na concorrência. Recorreu-se a um modelo de regressão linear múltipla para estabelecer relação entre a internacionalização e a performance do Grupo Parras, tendo-se concluído não existir relação linear e positiva, no período analisado, entre o indicador compósito de internacionalização a performance financeira e operacional; The Internationalization of Portuguese Wines: The Parras Group Case Study Abstract: Portugal has a commercial surplus about wine, and internationalization is very relevant in the strategy of companies in the wine sector. Based on a mixed approach, has been analyzed the internationalization and international marketing mix process of the Parras Group, where direct export was found as the predominant entry mode in different international markets. It was possible to group internationalization motivations as proactive and reactive, and identify the international experience and the flexibility as fundamental competences for internationalization. The Parras Group does not consider relevant the barriers to internationalization, and adopts an identical international marketing mix strategy for the different markets, based on costs and the competition. A multiple linear regression model was used to establish a relationship between the internationalization and the performance of the Parras Group. It was concluded that there was no linear and positive relationship between the composite indicator of internationalization and the financial and operational performance in the analyzed period.

Orientadores: Helena Teixeira Godoy, Isidro Hermosín-Gutiérrez
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Bagaço (cascas e sementes) e borra (sedimentos sólidos) são os mais abundantes subprodutos do processo de vinificação, pois o primeiro representa aproximadamente 5% do total de uva processada e, o segundo, 4% do volume total de vinho produzido. Alguns estudos demonstraram que os resíduos vinícolas contêm importantes compostos fenólicos, potentes antioxidantes, que não foram totalmente transferidos ao vinho durante o processo de vinificação, assim despertando interesse econômico e funcional. Sendo assim, o objetivo deste trabalho foi caracterizar os compostos fenólicos de resíduos vinícolas, e correlacionar os seus teores com a capacidade antioxidante. Foi determinado o teor de compostos fenólicos das uvas in natura, do bagaço (casca e semente) e borras, obtidas em duas safras (2011 e 2012), das variedades BRS Violeta, BRS Lorena, Cabernet sauvignon e Cabernet franc, por SPE e HPLC-DAD-ESI MS/MS. Também foi avaliado o efeito de três técnicas de secagem aplicadas aos subprodutos da vinificação (bagaço e borra): secagem em estufa a 50 °C (D50), secagem por spray-drying (SP), e secagem por liofilização (FD), assim como a estabilidade dos subprodutos secos D50 e SP, submetidos a 25 °C durante 0, 30 e 90 dias. A capacidade antioxidante foi avaliada por ORAC, FRAP, ABTS e ß-caroteno/ácido linoleico, e suas correlações com antocianinas e fenólicos totais. Foram identificadas 25 antocianinas e 9 piranoatocianinas nas diferentes amostras analisadas. A composição de antocianinas de BRS Violeta foi principalmente pelos derivados diglicosídeos. No entanto, nas amostras de Cabernet sauvignon e Cabernet franc as antocinaninas majoritárias foram 3-glicosídeos. As piranoantocianinas foram encontradas somente em cascas fermentadas das cultivares Cabernet sauvignon e Cabernet franc e nas borras de todas as cultivares. Os flavonois encontrados foram principalmente, quercetina, isoramnetina, miricetina, laricitrina e siringetina. Nas uvas predominaram os glicosilados, e nos resíduos obtiveram maiores proporções de agliconas livres, especialmente nas borras de vinho (85%). Na BRS Lorena, quercetina foi o flavonol majoritário nas cascas (91%) e nas borras (95%). Já em todas as amostras de BRS Violeta, os derivados do ácido caféico foram predominantes. Os ácidos caftárico (53%) e cutárico (17%) foram superiores nas amostras das cultivares Cabernet sauvignon e Cabernet franc. Em todas as amostras de uvas e borras detectou-se a presença de trans-resveratrol, trans-piceid e cis-piceid (com exceção da BRS Violeta). Nos resíduos secos em estufa a 50°C e spray-drying observou-se uma redução de até 50% no teor de compostos fenólicos totais dos diferentes resíduos das quatro variedades de uva no tempo zero, quando comparado com o liofilizado. Em todos os métodos de capacidade antioxidante, as amostras BRS Violeta demonstraram valores superiores quando comparadas a BRS Lorena, Cabernet sauvignon e Cabernet franc. Os subprodutos da vinificação secos apresentaram concentração elevada de compostos fenólicos totais, em média os valores oscilaram de 810 à 8557 mg/kg para casca fermentada; de 1515 à 9520 mg/kg para semente; e 1148 à 4261 mg/kg para borra, nas cultivares estudadas. Nas uvas inteiras secas utilizadas no processamento do vinho o teor de compostos fenólicos encontrados foi de 530 à 4330 mg/kg. Sendo assim, os subprodutos analisados possuem elevado teor de compostos antioxidantes e, portanto, com potencial para reaproveitamento industrial
Abstract: Grape marc (skins and seeds) and lees (sediment solids) are the most abundant by-products of the winemaking process, because the first represents approximately 5% of the total grapes processed and the second, 4% of the total volume of wine produced. Some studies have shown that winery residues contain phenolic compounds, potent antioxidants that were not fully transferred to the wine during the winemaking process, thus with economic and functional interest. Thus, the objective of this work was characterize the phenolic compounds of industrials residues generated by the vinification and correlate their levels with the antioxidant capacity. The phenolic content of grapes in natura, grape marc (skins and seeds), and lees, in two consecutive years (2011 and 2012), of varieties BRS Violeta, BRS Lorena, Cabernet sauvignon and Cabernet franc, was determined by SPE and HPLC-DAD-ESI MS/MS. The effect of three drying techniques applied to vinification by-products (grape marc and lees) was also evaluated: dried at 50 °C, drying by spray-drying and freeze-drying, as well as the stability of by-products dried submited at 25°C in 0, 30 and 90 days. The antioxidant capacity was evaluated by ORAC, FRAP, ABTS and ß-caroteno/linoleic acid, and their correlations with total anthocyanins and phenolics. Were identified 25 anthocyanins and 9 piranoathocyanins in the samples analyzed. The composition of anthocyanins BRS Violeta was mainly derived by diglucosides. However, in samples of Cabernet sauvignon and Cabernet franc antocynanins 3-glucosides were majority. The pyranoanthocyanins were found only in fermented skins of the cultivars Cabernet sauvignon and Cabernet franc and the lees of all cultivars. Flavonols were found mainly quercetin, isorhamnetin, myricetin, laricitrin, and syringetin. In grape glycosides predominated, and residues were obtained higher proportions of free aglycones, especially the lees of wine (85%). In BRS Lorena, type flavonol quercetin was the majority in the skin (91%) and the lees (95%). Already in all samples BRS Violeta, derivatives of caffeic acid were predominant. The caftaric acids (53%) and coutaric acid (17%) were high in the samples of the cultivars Cabernet sauvignon and Cabernet franc. In all samples of grapes and lees were detected the presence of trans-resveratrol, trans-piceid and cis-piceid (except BRS Violeta). In the residue dried at 50 °C and spray-drying showed a 50% reduction in the total phenolic content of the residues of four different varieties of grape at time zero when compared to the lyophilized. In all methods of antioxidant capacity, BRS Violeta samples showed higher values when compared to BRS Lorena, Cabernet sauvignon and Cabernet franc. The byproducts of winemaking had elevated total phenolics, average values ranged from 810 to 8557 mg/kg for fermented skins; 1515 to 9520 mg/kg for seeds, and 1148 to 4261 mg/kg for lees. In grapes used in the processing of wine the phenolic content was found of 530 to 4330 mg/kg dried grape. Thus, the by-products have a high content of antioxidant compounds and therefore have the potential for industrial reuse
Doutorado
Ciência de Alimentos
Doutora em Ciência de Alimentos

The goal of the Master's Thesis is to identify potential risks that consumers face at the wine market in the Czech Republic. Further, the Master's Thesis aim to find out what are the measures that protect a consumer and to suggest solutions to those areas where the protective measures do not work. The identification is carried out via the analysis of primary and secondary data. Primary data are surveyed by means of consumer research and interviews with experts. At the end of the Master's Thesis the results are summarized and the improving arrangements are put forward.

This diploma thesis analyzes the importance of wine tourism - enotourism for viticulture and winemaking in Slovakia. The main aim of this work is determining the relevance and importance of this form of tourism for wine producers. The theoretical part states the base for the research design and provides the introduction into wine tourism. It also describes the current situation of the viticulture and winemaking in Slovakia as well as the situation of the tourism industry and its performance. The analytical part of the work deals with the evaluation of the current situation of wine tourism in Slovakia and assumptions of its development. The core of the analytical part is a questionnaire survey, which charts the attitudes and opinions of the wine producers on issues of winemaking, wine business and wine tourism in Slovakia. The final part analyzes the questionnaire survey supported by theoretical bases of the first part of the thesis and evaluates the importance of enotourism for viticulture and winemaking in Slovakia. This part includes also suggestions for improving the cross-sectorial links between tourism, viticulture and winemaking in Slovakia in order to expansion of this form of tourism.

O processo de cultivo da uva e elaboração do vinho tinto varietal Marselan foi parcialmente acompanhado junto a uma vinícola do Vale dos Vinhedos (RS, Brasil), com o objetivo de verificar, com técnicas analíticas baseadas em feixes iônicos, como PIXE, alterações elementares no vinho devido ao seu processamento. Amostras de solo, folhas e galhos das videiras, uvas, mosto e vinhos foram coletadas nas etapas mais importantes do ciclo de cultivo da uva e de produção do vinho. Os alvos foram preparados de acordo com as características de cada material e exigências da técnica e, então, irradiados no sistema de PIXE do Laboratório de Implantação Iônica (IFUFRGS). Os resultados, de acordo com as análises estatísticas realizadas com teste t, ANOVA FATOR ÚNICO e Tukey, mostraram que a composição elementar do solo é constituída por Mg, Al, P, K, Ti, Mn, Fe, As, Rb e Zr. Além disso, foi verificada contaminação superficial devido, principalmente, ao Ca e Cu. Quanto ao cultivo, folhas e galhos revelaram a influência das aplicações de produtos químicos pelo acúmulo de alguns elementos no período de latência. A concentração elementar das uvas variou em função do crescimento e amadurecimento dos bagos. Em geral, durante o processo de vinificação e, em especial durante a fermentação, a concentração de vários elementos aumentou. Este foi o caso de elementos como o Mg, K, Rb e Sr. Por outro lado, alguns elementos tiveram um decréscimo na concentração devido a precipitação, como o Ca e o Cu.
The study of the Marselan grape cultivation and winemaking process was partially carried out in a winery located in Vale dos Vinhedos (RS, Brazil). The main goal was to employ ion-based techniques like PIXE in order to obtain elemental variations throughout the production chain of wine. Soil, vine leaves and branches, grapes, must and wine samples were collected at every important step of the production chain. Samples were prepared according to the peculiarities of each material and technique requirements. All PIXE measurements were carried at the Ionic Implantation Laboratory (IF-UFRGS). The data were analyzed with t test, ANOVA ONE WAY and Tukey. The elemental composition of soil comprises Mg, Al, P, K, Ti, Mn, Fe, As, Rb and Zr. Other elements like Cu and Ca were present over superficial layers and might be related to contaminants. With respect to the cultivation process, leaves and branches suffered from the influence of chemicals accumulated during the latency period. The elemental concentration of grapes changed during the berry growth and ripening. In general, later steps including fermentation tended to increase the concentrations of several elements like Mg, K, Rb and Sr. On the other hand, other elemental concentrations decreased due to precipitation, like Ca and Cu.

Доступ до роботи тільки на території бібліотеки ОНЕУ, для переходу натисніть на посилання нижче
У роботі розглядаються теоретичні засади започаткування власної справи у виноробній сфері: розглянуто бізнес-ідею започаткування власної справи; досліджуються нормативно-правове регулювання підприємницької діяльності в Україні у виноробній сфері. Проаналізовано конкурентне середовище у виноробній сфері в Одеській області та визначені внутрішні конкурентні переваги створюваного підприємства з виробництва та продажу вина. Розраховано витрати на створення ті функціонуванні підприємства з виробництва та продажу вина. Спрогнозовано прибуток від реалізації товарів та послуг. Проведено оцінку економічної ефективності проекту. Проаналізовані можливі ризики та запропоновані заходи щодо їх мінімізації.
The work deals with the theoretical principles of starting a business in the wine industry. Therefore, author considers the business-idea of starting business in in the wine industry; he also examines the regulatory and legal regulation of entrepreneurial activity in Ukraine in the wine industry. The competitive environment of preschool education in Odessa were analyzed as well as internal competitive advantages of the created enterprise for the production and sale of wine. The costs of establishing and operating of the enterprise for the production and sale of wine were calculated. Income from the sale of services forecasted. The economic efficiency of the project reviewed. The possible risks analyzed and measures to minimize them proposed.

Marlborough is the largest wine region in New Zealand and Sauvignon blanc cultivars represented about 60 % of the vineyard area in 2009. The main compounds responsible for the most intense aromas in Sauvignon blanc wines had been assumed to be methoxypyrazines, responsible for the herbaceous, capsicum and asparagus aromas, and varietal thiols, responsible for fruity aromas such as grapefruit, citrus or passion fruit. However, the aromatic potential of Sauvignon blanc wines is too complex to be limited to just these two families of compounds. This study has shown that further groups of aroma compounds (esters, terpenes, C6- and higher alcohols, fatty acids, C13- norisoprenoids, cinnamates and anthranilates) could also be involved in the characteristic aroma of these wines. Winemakers divide the Marlborough Sauvignon blanc growing area into 7 sub-regions, and ascribe different aroma profiles to wines coming from these regions. An extensive study of the compounds that impact on Sauvignon blanc aroma has been undertaken with over fifty important impact aroma compounds quantified in 54 wines from different sub-regions within Marlborough. Some important variations with regard to the Marlborough sub-regions have been revealed, and the extent to which these differences in chemical composition can impact on wine sensory differences has been assessed. A further aim of this research was to assess the optimum small scale winemaking protocol in order to obtain aroma composition results in research wines comparable to those found in commercial wines. Different conditions in the early stages of the winemaking process were studied: destemming and crushing of the grapes, differences between hand-picked and machine-harvested grapes, and the use of maceration enzymes. The results have shown that both destemming and crushing of the grapes are needed to obtain wines with an aroma composition similar to the commercial wines.

La rotundone est le principal contributeur à l’arôme poivré des vins rouges. Les travaux menés dans le cadre de cette thèse de doctorat ont permis de faire progresser les connaissances sur cette molécule au niveau sensoriel, sur son appréciation par le consommateur et sur les facteurs environnementaux, viticoles et oenologiques impactant ses niveaux de concentration dans les vins. Une corrélation significative, entre l’intensité des notes poivrées perçues à la dégustation et la concentration en rotundone des vins au sein d’un échantillon composé de 21 vins, a été établie. Le profil de consommation des vins riches en rotundone a également été identifié. Le consommateur préférant les vins poivrés s’apparente à un amateur éclairé possédant un budget par bouteille de vin supérieur aux autres consommateurs. Aucun seuil de rejet n’a pu être établi pour la rotundone et le caractère positif de la molécule a été démontré dans la plupart des cas. Les recherches menées sur l’écophysiologie de la rotundone suggèrent que la production de la molécule a lieu dans la baie et peut être influencée par des facteurs abiotiques (quantité d’eau, niveau éclairement) et biotiques (infection par Erysiphe necator et Botrytis cinerea). La date de récolte, le clone, et quelques pratiques viticoles ont été identifiés comme des leviers possibles pour favoriser l’accumulation de la rotundone dans les vins. Aucune des techniques de vinification et des variables fermentaires testées n’ont permis d’augmenter les niveaux en rotundone des vins en comparaison avec un témoin vinifié traditionnellement. Ceci signifie que les efforts pour maximiser la concentration en rotundone des vins doivent être entrepris dès le vignoble
Rotundone is the main compound responsible for peppery aroma in red wines. Researches carried out in the frame of this PhD thesis have contributed to advance the knowledge on this molecule from a sensory point of view, on its consumer acceptance and on the environmental, viticultural and enological factors affecting its concentration in wines. A significant correlation between the intensity of peppery notes at tasting, and the rotundone concentration in wines within a panel composed of 21 samples, was established. The consumption profile of those who prefer peppery wines was also identified. Consumers who appreciate wines with a peppery sensory profile are generally wine connoisseurs who are willing to pay more for a bottle of wine than the average consumer. No consumer rejection threshold was determined, and in most cases, the positive character of the molecule was demonstrated. Researches carried on rotundone ecophysiology suggest that rotundone production occurs in grape berries and can be affected by abiotic (amount of water, quantity of light) and biotic (infection by Erysiphe necator and Botrytis cinerea) factors. The date of harvest, the clone and some viticultural practices were identified as possible leverages to enhance rotundone accumulation in wines. None of the studied winemaking techniques and fermentation variables resulted in enhanced rotundone concentrations in comparison with a control treatment vinified traditionally. This means that efforts to maximize rotundone in wines must be undertaken in vineyards

La utilización de bacterias iniciadoras de fermentación maloláctica es de fundamental importancia para los elaboradores de vino comprometidos con la producción de vinos de alta calidad y sin riesgos para la salud, ya que estas bacterias han sido seleccionadas como poco productoras de aminas biógenas. Sin embargo, en ciertas condiciones se obtienen vinos con altos niveles de aminas biógenas, aun cuando estos vinos han sido inoculados con bacterias seleccionadas. En el presente trabajo, con la tipificación de bacterias aisladas de la fermentación maloláctica usando un método basado en RAPD-PCR, se demostró que el estárter maloláctico puede tener diferentes niveles de implantación y que a su vez, esto se correlaciona con la producción de aminas biógenas durante la fermentación maloláctica, lo cual explicaría los altos niveles de aminas obtenidos en vinos inoculados con estárteres malolácticos. Para entender como las diferentes prácticas enológicas afectan la implantación del estárter maloláctico, lisozima, nutrientes, co-inoculación con levaduras, o siembra del estárter por diferentes métodos (inoculación directa o pie de cuba) fueron estudiados respecto al nivel de implantación y producción de aminas biógenas. Luego de la fermentación maloláctica, las aminas biógenas pueden aumentar, degradarse o estar constantes durante el almacenamiento del vino una vez que este ha sido embotellado. Esto puede crear incertidumbre respecto al nivel que las aminas biógenas tendrán en el momento de su comercialización. En la segunda parte de esta tesis, se puso en evidencia la presencia de microorganismos y enzimas libres en el vino embotellado capaces de producir histamina durante su almacenamiento; también se sospecha la presencia de enzimas capaces de degradar histamina. Se estudió la relación entre esto, y el contenido de aminas al final de un año de almacenamiento; diferentes perfiles de vinos se identificaron: histaminogénicos, histaminoliticos e histamin-estables. Indicadores para estimar el riesgo de producción de histamina fueron propuestos. Siguiendo con el interés de investigar tecnologías que ayuden a producir vinos sin peligro para la salud del consumidor, el uso de técnicas biológicas para reducir los niveles de ocratoxina A (OTA) en vinos fue investigado. En la tercera parte de esta tesis, estárteres malolácticos fueron evaluados respecto a su capacidad para reducir OTA durante la fermentación maloláctica. Algunos estárteres, fueron capaces de reducir OTA en vinos conteniendo 13% de etanol. La reducción de OTA parece relacionarse con el pH del vino. La interacción entre la formación de aglomerados de protein-polifenoles en función del etanol y pH, y la interacción que esto podría tener en la capacidad de adopción fue discutido. La modificación de la pared celular debido al proceso de liofilización de los estárteres como causa posible de la capacidad reductora de los estárteres fue también abordado. Los resultados son prometedores, sin embargo, sería necesario profundizar en la investigación para entender los mecanismos ligados a la reducción de OTA producido por los estárteres malolácticos en vinos.
Malolactic bacterial starters are used in the production of high quality and safe wines because of their capabilities to produce low levels of biogenic amines and perform the malolactic fermentation under controlled conditions. However, in certain conditions, inoculated wines can have high biogenic amines content which is in contradiction with the expected performance of the bacterial starter. In the present work, it was demonstrated, by typification of bacterial strains using RAPD-PCR, that malolactic starters can present different levels of implantations and this is correlated with the biogenic amines produced during the malolactic fermentation, which can explain the unexpected results when malolactic starters are used. In order to understand how the implantation is affected by oenological practices, lysozyme, nutrients, co-inoculation with yeast, or application of different seeding methods (direct inoculation or pied de cuve) were studied regarding their impact on the level of implantation and biogenic amines production. On the other hand, biogenic amines in bottled wine evolve all along the storage period. Their content increase, decrease or stay constant, which creates incertitude regarding the levels of biogenic amines that the wine will have in the moment of its commercialization. In the second part of this thesis, we demonstrated the presence of microorganisms with decarboxylase capabilities and exocellular amine-decarboxylase enzymes in the bottled wine. The presence of amine-degrading enzymes is also suspected. The link between the latter and the biogenic amines found at the end of a year of storage were related and different histamine profiles were determined for the wines: histaminolitic, histaminogenic and histamine-stable. Some indicators to measure the risk of histamine development are proposed. In the search for technological means to help wine-makers to elaborate safe wines, the use of biological tools to reduce the levels of ochratoxin A (OTA) in wines was investigated. In the third part of this thesis, malolactic starters were screened by their property to reduce OTA during the malolactic fermentation. Some malolactic starters were able to obtain high OTA reductions in wines containing 13% ethanol. OTA reduction by starters seems to be related to the pH. The interaction between protein-polyphenols haze formation as function of ethanol and pH and the interaction that this might have on absorption phenomenon is discussed. Modification of cell wall by lyophylization process and its consequences on adsorption properties are also analyzed. The results are encouraging but more investigation is needed to understand OTA reduction mechanism carried-out by malolactic bacterial strains in wines.

La Valle d'Aosta, pur non avendo grandi superfici destinate alla viticoltura, è caratterizzata dalla presenza di un ricco patrimonio ampelografico di cui fanno parte dodici varietà autoctone a bacca rossa: Bonda, Cornalin, Crovassa, Fumin, Mayolet, Ner d'Ala, Petit rouge, Premetta, Roussin, Roussin de Morgex, Vien de Nus e Vuillermin. Malgrado i numerosi vitigni menzionati, nella produzione dei vini a D.O.C troviamo in prevalenza il Petit rouge e poche altre varietà che, nell'insieme, rappresentano circa il 34% della produzione totale. Al fine di implementare la presenza di prodotti tipici che esprimano i caratteri distintivi della zona di provenienza sono state approfondite le conoscenze dei vitigni autoctoni per evidenziarne le attitudini e le potenzialità per la produzione di vini rossi di qualità. Allo stesso scopo sono stati valutati gli effetti dell'applicazione di alcune tecniche di vinificazione alternative sull'espressione dei caratteri qualitativi del Petit rouge, le cui uve sono da tempo vinificate in purezza o in assemblaggi nella produzione di vini a D.O.C.
Aosta Valley has a little viticulture surface and it is characterised by a rich ampelographic collection including the following twelve red grape autochthonous varieties: Bonda, Cornalin, Crovassa, Fumin, Mayolet, Ner d'Ala, Petit rouge, Premetta, Roussin, Roussin de Morgex, Vien de Nus e Vuillermin. Only the 34% of the D.O.C. wine production is represented by some of the above mentioned cultivars, in particular the Petit Rouge, despite of the huge number of cultivars. The Petit rouge is used in purity or in miscellaneous in the D.O.C. wine production. In order to implement the presence of typical products, this study was carried out to evaluate the aptitude of Aosta Valley ancient grapes to produce quality red wines. Moreover to improve quality of the most diffused Aosta Valley red wine the effects of some alternative winemaking were evaluated on the Petit rouge characters.

Protein-induced wine haze is a major concern to the wine industry worldwide. While the presence of protein haze is unlikely to affect the sensory profile, consumers will generally reject wines containing hazes as they appear microbially spoiled. Consequently, an important step during commercial winemaking is to treat wines with bentonite, which removes heat unstable proteins by adsorption, and prevents haze formation. Whilst this process is effective, it is claimed to adversely affect the quality of the treated wine under certain conditions. Furthermore, 5-10% of the wine volume is typically occluded in bentonite lees. This wine is either lost or substantially diminished in quality and value during recovery. Therefore the development of alternative and economically viable process technologies that maintain wine quality and reduce costs would be highly desirable. This thesis is concerned with the development of alternative and innovative approaches to bentonite treatment of wine. Particular emphasis was placed on developing practical research outcomes that could be readily commercially adopted. Pursuant to this, fundamental research regarding the mechanics of protein adsorption onto bentonite was undertaken to gain an understanding of how bentonite properties relate to adsorption and settling behaviour in wine. The effect of bentonite heat treatment on protein adsorption performance and settling behaviour in a model wine was also investigated. In general, heating was found to increase the initial hindered settling velocity and reduce both protein adsorption capacity and the final volume of lees. Particle size, pH and cation exchangeability of bentonites and the changes that occur to these properties on heating are related to the nature of bonding between cations and the clay surface, as are protein adsorption performance and settling behaviour. Partial Least Squares (PLS) Analysis showed that the variance in individual cation exchangeability and the total cation exchange capacity was primarily responsible for the observed variance in protein adsorption performance and settling behaviour. PLS analysis was also used to develop correlations for the prediction of adsorption and settling behaviour, based on the physical and chemical properties of the bentonites tested. Qualitative comparison of the volume fraction of model wine occluded by each of the bentonites indicated that certain heat treatments may result in a combination of protein adsorption performance and settling behaviour which would produce a significant reduction in wine loss. The effect of different factors on adsorption of a purified grape protein (VVTL1) in a model wine was investigated using a factorial design approach with surface response analysis. Adsorption of VVTL1 by sodium bentonite was well characterised by the Langmuir adsorption isotherm. pH, temperature, potassium concentration ([K]), and the pH*[K]interaction were all found to have a significant effect (p < 0.05) on the adsorption capacity. Block effects appeared to correctly correlate with bentonite slurry age, suggesting that increasing slurry age may have a positive effect on adsorption capacity. Ethanol concentration, phenolic (caffeic acid and catechin) oncentration, sugar (glucose and fructose) concentration, as well as the pH*temperature and temperature*[K] interactions did not have a significant effect. The equilibrium constant was found to be independent of the factors studied. This may be explained by changes in protein structure and charge with pH, which affect electrostatic interaction with the bentonite surface. Variation in potassium concentration can cause similar effects and may also influence adsorption capacity by affecting bentonite swelling and zeta potential. This knowledge was applied to the development of in-line dosing of bentonite as an alternative process strategy for commercial use. Field tests of in-line dosing at a commercial winery were conducted on a Sultana wine and Gordo (Muscat of Alexandria) juice with Vitiben and SIHA-Aktiv-Bentonit G bentonites. Fining performance was monitored by heat testing and quantification of heat unstable protein by HPLC. Heat test turbidity and heat unstable protein concentration were reduced in a similar manner upon fining. These reductions were achieved with a contact time of less than two minutes. Sensory evaluation of Sultana wine fined with Vitiben by balanced reference duo-trio difference tests did not detect any difference between untreated, in-line dosed and batch fined wine. A dynamic simulation model of in-line dosing was developed and compared with field trial results, marking the first quantitative study of the dynamic adsorption kinetics of wine protein adsorption onto bentonite. The simulation results confirmed the rapid adsorption behaviour observed during field testing, and provided strong evidence that protein adsorption occurs predominantly on the external particle surface only, with adsorption kinetics being limited by external-film mass transfer. Incomplete separation of bentonite from wine/juice during centrifugation produced a carryover of up to 30% of the added bentonite into the clarified wine. If this problem can be overcome, use of in-line dosing instead of batch fining could eliminate significant value losses presently arising from quality downgrades of wine recovered from bentonite lees by rotary drum vacuum filtration. Moreover, in-line dosing of selected heattreated bentonites under optimal wine or juice conditions may provide even further costs savings whilst maintaining wine quality.
Thesis (Ph.D.)-- University of Adelaide, School of Chemical Engineering, 2006.

Protein-induced wine haze is a major concern to the wine industry worldwide. While the presence of protein haze is unlikely to affect the sensory profile, consumers will generally reject wines containing hazes as they appear microbially spoiled. Consequently, an important step during commercial winemaking is to treat wines with bentonite, which removes heat unstable proteins by adsorption, and prevents haze formation. Whilst this process is effective, it is claimed to adversely affect the quality of the treated wine under certain conditions. Furthermore, 5-10% of the wine volume is typically occluded in bentonite lees. This wine is either lost or substantially diminished in quality and value during recovery. Therefore the development of alternative and economically viable process technologies that maintain wine quality and reduce costs would be highly desirable. This thesis is concerned with the development of alternative and innovative approaches to bentonite treatment of wine. Particular emphasis was placed on developing practical research outcomes that could be readily commercially adopted. Pursuant to this, fundamental research regarding the mechanics of protein adsorption onto bentonite was undertaken to gain an understanding of how bentonite properties relate to adsorption and settling behaviour in wine. The effect of bentonite heat treatment on protein adsorption performance and settling behaviour in a model wine was also investigated. In general, heating was found to increase the initial hindered settling velocity and reduce both protein adsorption capacity and the final volume of lees. Particle size, pH and cation exchangeability of bentonites and the changes that occur to these properties on heating are related to the nature of bonding between cations and the clay surface, as are protein adsorption performance and settling behaviour. Partial Least Squares (PLS) Analysis showed that the variance in individual cation exchangeability and the total cation exchange capacity was primarily responsible for the observed variance in protein adsorption performance and settling behaviour. PLS analysis was also used to develop correlations for the prediction of adsorption and settling behaviour, based on the physical and chemical properties of the bentonites tested. Qualitative comparison of the volume fraction of model wine occluded by each of the bentonites indicated that certain heat treatments may result in a combination of protein adsorption performance and settling behaviour which would produce a significant reduction in wine loss. The effect of different factors on adsorption of a purified grape protein (VVTL1) in a model wine was investigated using a factorial design approach with surface response analysis. Adsorption of VVTL1 by sodium bentonite was well characterised by the Langmuir adsorption isotherm. pH, temperature, potassium concentration ([K]), and the pH*[K]interaction were all found to have a significant effect (p < 0.05) on the adsorption capacity. Block effects appeared to correctly correlate with bentonite slurry age, suggesting that increasing slurry age may have a positive effect on adsorption capacity. Ethanol concentration, phenolic (caffeic acid and catechin) oncentration, sugar (glucose and fructose) concentration, as well as the pH*temperature and temperature*[K] interactions did not have a significant effect. The equilibrium constant was found to be independent of the factors studied. This may be explained by changes in protein structure and charge with pH, which affect electrostatic interaction with the bentonite surface. Variation in potassium concentration can cause similar effects and may also influence adsorption capacity by affecting bentonite swelling and zeta potential. This knowledge was applied to the development of in-line dosing of bentonite as an alternative process strategy for commercial use. Field tests of in-line dosing at a commercial winery were conducted on a Sultana wine and Gordo (Muscat of Alexandria) juice with Vitiben and SIHA-Aktiv-Bentonit G bentonites. Fining performance was monitored by heat testing and quantification of heat unstable protein by HPLC. Heat test turbidity and heat unstable protein concentration were reduced in a similar manner upon fining. These reductions were achieved with a contact time of less than two minutes. Sensory evaluation of Sultana wine fined with Vitiben by balanced reference duo-trio difference tests did not detect any difference between untreated, in-line dosed and batch fined wine. A dynamic simulation model of in-line dosing was developed and compared with field trial results, marking the first quantitative study of the dynamic adsorption kinetics of wine protein adsorption onto bentonite. The simulation results confirmed the rapid adsorption behaviour observed during field testing, and provided strong evidence that protein adsorption occurs predominantly on the external particle surface only, with adsorption kinetics being limited by external-film mass transfer. Incomplete separation of bentonite from wine/juice during centrifugation produced a carryover of up to 30% of the added bentonite into the clarified wine. If this problem can be overcome, use of in-line dosing instead of batch fining could eliminate significant value losses presently arising from quality downgrades of wine recovered from bentonite lees by rotary drum vacuum filtration. Moreover, in-line dosing of selected heattreated bentonites under optimal wine or juice conditions may provide even further costs savings whilst maintaining wine quality.
Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2006.

Bibliography: p. 166-189.
xii, 189 p. : ill. ; 30 cm.
This thesis describes the development and use of stable isotope dilution analysis techniques for measuring wine components associated with oak-barrel maturation and with taint derived from cork closures during bottle maturation. (introduction)
Thesis (Ph.D.) -- University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, 2001

Bibliography: p. 166-189.
xii, 189 p. : ill. ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
This thesis describes the development and use of stable isotope dilution analysis techniques for measuring wine components associated with oak-barrel maturation and with taint derived from cork closures during bottle maturation. (introduction)
Thesis (Ph.D.)--Adelaide University, Dept. of Horticulture, Viticulture and Oenology, 2001

Polyfunctional thiols (also known as varietal thiols) with odour detection thresholds (ODTs) in the nanogram per litre range are one of the most potent volatiles present in wine and are regarded as odour-active compounds affording significant sensory contributions. These compounds have been intensively investigated for the past few decades, along with their non-volatile grape-derived precursors in more recent years, but knowledge of the analysis, biogenesis, and fate of thiols, as well as the influences of environmental and winemaking factors, is still incomplete. This thesis therefore begins by reviewing the current knowledge of polyfunctional thiols in wine and precursors in grapes (Chapter 1), and then covers the analytical approaches that have been developed to identify and quantify thiols in foods and beverages, with a particular focus on wine (Publication in Chapter 2). A number of original research studies (Publications in Chapters 3 to 6) are then presented to address the knowledge gaps related to characteristic thiols in wine and their precursors in grapes. Polyfunctional thiols 3-sulfanylhexan-1ol (3-SH) and 3-sulfanylhexyl acetate (3- SHA) are two of the most evaluated thiols in wine. 3-SH and 3-SHA are chiral molecules, which give rise to pairs of enantiomers that differ in aroma quality and ODT. However, chiral analytical methods required to study 3-SH and 3-SHA enantiomers in wine were essentially non-existent. Addressing this gap, a novel stable isotope dilution assay (SIDA) with chiral high-performance liquid chromatography with tandem mass spectrometry (HPLC–MS/MS) using a polysaccharide-based column has been developed and validated for analysing the enantiomers of 3-SH and 3-SHA, after extraction from wine as their 4- thiopyridine derivatives. Authentic derivatives were synthesised to enable chiral column screening, and method validation encompassed calibration range, linearity, accuracy, precision, limit of detection, and matrix effects. The validated method demonstrated excellent analytical performance and offers opportunities for further research around chirality of polyfunctional thiols. By applying this method, the distribution pattern of enantiomers of 3-SH and 3-SHA in a set of commercial wines has been reported (Publication in Chapter 3). The formation of 3-SH and 3-SHA during fermentation involves conjugated precursors that are present as pairs of diastereomers in grapes. However, there was no literature on thiol precursor stereochemistry in grapes in relation to thiol chirality in wine. Employing the newly developed method for analysing thiol enantiomers, the relationship between precursor diastereomers in grapes and thiol enantiomers in wine was examined for the first time through a fermentation trial using five co-located clones of Sauvignon blanc grapes (Publication in Chapter 4). No correlation was observed between precursor diastereomers in grapes analysed by SIDA HPLC–MS/MS and 3-SH or 3-SHA enantiomers in wines measured by SIDA chiral HPLC–MS/MS, but the results have provided insight that can be further explored to understand the implications of thiol biogenesis on thiol precursor stereochemistry. Tackling thiols and their precursors from a viticultural and oenological perspective, the impacts of sub-region within one geographic indication, grape clone, grape amino acids, yeast strain, commercial enzyme, fermentation nutrient, and pre-fermentation freezing have been assessed in controlled fermentation trials with Sauvignon blanc (Publications in Chapter 4 and 5). Substantial intraregional variations existed among thiol precursors and thiols in the examined grapes and wines, respectively, and clonal differences were noted at the diastereomeric and enantiomeric levels for precursors and thiols, respectively. In terms of the impact of grape metabolites on thiols and precursors, grape amino acids were revealed for the first time to have stronger correlations to 3-SH precursors in grapes (e.g., |r| > 0.73 and 0.62 for glutamic acid and glycine) than thiols in wines (|r| < 0.42), highlighting the potential interaction between grape amino acids and thiol precursor metabolism in grapes. With regard to thiol management during winemaking, significant elevations of polyfunctional thiols in wine occurred with the use of a commercial enzyme in juices (up to an approximate two-fold increase in a clone-dependent manner) or pre-fermentation freezing treatment on fresh grapes (up to an approximate 10- fold enhancement regardless of clone). These practical approaches and novel results are of potential interest for winemakers who seek to be one step closer to thiol management during winemaking. The fate of polyfunctional thiols in wine requires continued investigation to comprehend the impacts on varietal aroma profiles of wine. Based on the coexistence of 3-SH and acetaldehyde in wine, the presence of a new volatile sulfur compound (VSC) with an oxathiane structure was theorised. After the synthesis of a deuterated standard and the development of a SIDA headspace solid-phase microextraction (HS–SPME) with gas chromatography and mass spectrometry (GC–MS) method, 2-methyl-4-propyl-1,3-oxathiane was identified and quantitated in wine for the first time. Only detectable as the cis-isomer, this compound strongly correlated (r = 0.72) with the concentration of 3-SH determined by HPLC–MS/MS analysis. The ODT of this newly discovered wine volatile was determined in a neutral white wine. Concentrations of cis-2-methyl-4- propyl-1,3-oxathiane (up to 460 ng/L) determined in a range of surveyed commercial wines were below the measured ODT of 7.1 μg/L. Nonetheless, the presence of this new wine volatile still has potential implications for wine aroma, due to its direct link with the fate of important wine aroma compound 3-SH. On one hand, this may help account for 3-SH that is lost during fermentation and ageing, and on the other hand, a sizeable proportion of 3-SH could be masked as the oxathiane, thus diminishing the impact of 3-SH on wine aroma (Publication in Chapter 6). In summary, this PhD thesis has combined modern analytical methods, chemistry synthesis, fermentation trials, and sensory testing to shed light on aspects of wine aroma related to important polyfunctional thiols and their precursors. The outcomes not only contribute to a better scientific understanding of thiol chemistry but also offer opportunities for potential industrial applications.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2019

Hen egg white lysozyme is a hydrolytic enzyme effective at preventing the growth of Gram positive bacteria by degrading the bacterial cell wall to a point of cell lysis. Investigating lysozyme as a processing tool in wine to control the growth of lactic acid bacteria and malolactic fermentation has significant commercial interest. In this project, the interactions of lysozyme with wine components and wine was evaluated along with the efficacy of lysozyme in preventing malolactic fermentation (MLF) in Oregon Pinot Noir and Chardonnay. The information from this work, together with results from similar projects, will allow the development of guidelines for lysozyme use in commercial wine. Interactions of lysozyme with wine components were evaluated by measurement of enzymatic activity in the presence of wine acids, ethanol, and phenolics. Enzyme inhibition was observed, to various degrees, with all wine components. Crude grape tannin altered the availability of free enzyme by complexing to lysozyme and forming a precipitate. In a model wine system, lysozyme activity was reduced by 50% when tannin was present. Lysozyme addition to red wine resulted in a reduction in pigmented compounds and detectable sensory differences. Wine trials evaluated the efficacy of lysozyme in completely preventing malolactic fermentation (MLF) and terminating MLF midway through fermentation in Oregon Pinot Noir and Chardonnay. Vintages from 1993 and 1994 were treated without SO₂, with SO₂, with SO₂ plus a starter culture of Leuconostoc oenos. Each lot was divided into 0 ppm lysozyme (control), 250 ppm lysozyme, 500 ppm lysozyme, and 1000 ppm lysozyme. Lactic acid bacteria were enumerated monthly, for ten months. Lysozyme prevented malolactic fermentation in all wines at the treatment levels of 500 and 1000 ppm. In the 1993 Pinot Noir, 250 ppm lysozyme prevented MLF but only delayed MLF in the 1994 vintage. Lysozyme effectively terminated MLF at a concentration between 200 and 300 ppm in both Pinot Noir and Chardonnay.
Graduation date: 1996

Ochratoxin A (OA), a nephrotoxin and potential carcinogen, has been found in many foods, including grapes and grape products. Limits of 2 μg/kg in wine and 10 μg/kg in dried vine fruit have been introduced by the European Union. This study presents information on the ecology of ochratoxin A production by black Aspergillus spp. in Australian vineyards, and the passage of the toxin throughout winemaking. Aspergillus niger and A. carbonarius were isolated from vineyard soils in 17 of 17, and four of 17 Australian viticultural regions, respectively. A. aculeatus was isolated infrequently. All thirty-two isolates of A. carbonarius and three of 100 isolates of A. niger produced OA. Of Australian A. niger isolates analysed for restriction fragment length polymorphisms within the internal transcribed spacer region of 5.8S ribosomal DNA, 61 of 113 isolates, including the three toxigenic isolates, were of type N pattern, and 52 were type T. A selection of these A. carbonarius and A. niger aggregate isolates, as well as imported isolates, were compared using enterobacterial repetitive intergenic consensus (ERIC)-PCR, amplified fragment length polymorphisms (AFLP) and microsatellite markers. ERIC and AFLP clearly differentiated A. niger from A.carbonarius. AFLP further divided A. niger into types N and T. Six polymorphic microsatellite markers, developed specifically for A. niger, also differentiated strains into N and T types. There was no clear relationship between genotypic distribution and ochratoxigenicity, substrate or geographic origin. The survival of A. carbonarius spores on filter membranes was examined at water activities (aw) 0.4-1.0, and at 1 °C, 15 °C, 25 °C and 37 °C. Survival generally increased at lower temperatures. The lowest water activity, 0.4, best supported the survival of spores, but 0.6- 0.9 aw was often deleterious. Complex interactions between temperature and water activity were observed. Viability of A. carbonarius spores on filter membranes decreased ca 10[superscript 5] fold upon exposure to sunlight, equivalent to 10 mWh of cumulative ultraviolet irradiation at 290-400 nm. Growth and toxin production were examined for five isolates of A. carbonarius and two of A. niger on solid medium simulating juice at early veraison, within the range 0.98-0.92 aw, and at 15 °C, 25 °C, 30 °C and 35 °C. Maximum growth for A. carbonarius and A. niger occurred at ca 0.965 aw / 30 °C and ca 0.98 aw / 35 °C, respectively. The optimum temperature for OA production was 15 °C and little was produced above 25 °C. The optimum aw for toxin production was 0.95 for A. niger and 0.95-0.98 for A. carbonarius. Toxin was produced in young colonies, however, levels were reduced as colonies aged. Black Aspergillus spp. were more commonly isolated from the surface than from the pulp of berries, and increased with berry maturity, or damage. A. niger was isolated more frequently than A. carbonarius and A. aculeatus. Populations of A. carbonarius inoculated onto bunches of Chardonnay and Shiraz decreased from pre-bunch closure to early veraison. Populations from veraison to harvest were variable, and ncreased in bunches with tight clustering and splitting. In a trial with Semillon bunches, omitting fungicide sprays after flowering did not increase the development of Aspergillus rot. Inoculation of bunches with A. carbonarius spore suspension did not necessarily result in Aspergillus bunch rot. In vitro trials suggested that the severity of rot was mediated primarily by the degree of berry damage, followed by the extent of spore coverage. No clear trends regarding cultivar susceptibility were observed. For Semillon bunches inoculated with A. carbonarius spores with and without berry puncture, increased susceptibility to rot and OA formation was associated with berry damage, in particular at greater than 12.3 °Brix (20 d before harvest). OA contamination of bunches was related to the number of mouldy berries per bunch, with shrivelled, severely mouldy berries the primary source of OA. Puncture-inoculation of white grapes (Chardonnay and Semillon) and red grapes (Shiraz) on the vine with A. carbonarius resulted in berries containing OA. Inoculated grapes displayed greater total soluble solids due to berry shrivelling, and greater titratable acidity due to production of citric acid by the fungus. Samples taken throughout vinification of these grapes were analysed for OA. Pressing resulted in the greatest reduction in OA (68-85% decrease in concentration, compared with that of crushed grapes). Additional reductions occurred at racking from grape and gross lees, and after storage. OA was removed by binding to marc, grape and gross lees. Pectolytic enzyme treatment of white must, bentonite juice fining, recovery of juice or wine from lees, and static or rotary style fermentation of red must, had no effect on OA contamination. Bentonite in white wine (containing 56 mg/L grape-derived proteins) and yeast hulls in red wine were effective fining agents for removing OA. Findings from these studies may contribute to the improvement of strategies to minimise OA in Australian wine and dried vine fruit.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture and Wine, 2005.

Ochratoxin A (OA), a nephrotoxin and potential carcinogen, has been found in many foods, including grapes and grape products. Limits of 2 μg/kg in wine and 10 μg/kg in dried vine fruit have been introduced by the European Union. This study presents information on the ecology of ochratoxin A production by black Aspergillus spp. in Australian vineyards, and the passage of the toxin throughout winemaking. Aspergillus niger and A. carbonarius were isolated from vineyard soils in 17 of 17, and four of 17 Australian viticultural regions, respectively. A. aculeatus was isolated infrequently. All thirty-two isolates of A. carbonarius and three of 100 isolates of A. niger produced OA. Of Australian A. niger isolates analysed for restriction fragment length polymorphisms within the internal transcribed spacer region of 5.8S ribosomal DNA, 61 of 113 isolates, including the three toxigenic isolates, were of type N pattern, and 52 were type T. A selection of these A. carbonarius and A. niger aggregate isolates, as well as imported isolates, were compared using enterobacterial repetitive intergenic consensus (ERIC)-PCR, amplified fragment length polymorphisms (AFLP) and microsatellite markers. ERIC and AFLP clearly differentiated A. niger from A.carbonarius. AFLP further divided A. niger into types N and T. Six polymorphic microsatellite markers, developed specifically for A. niger, also differentiated strains into N and T types. There was no clear relationship between genotypic distribution and ochratoxigenicity, substrate or geographic origin. The survival of A. carbonarius spores on filter membranes was examined at water activities (aw) 0.4-1.0, and at 1 °C, 15 °C, 25 °C and 37 °C. Survival generally increased at lower temperatures. The lowest water activity, 0.4, best supported the survival of spores, but 0.6- 0.9 aw was often deleterious. Complex interactions between temperature and water activity were observed. Viability of A. carbonarius spores on filter membranes decreased ca 10[superscript 5] fold upon exposure to sunlight, equivalent to 10 mWh of cumulative ultraviolet irradiation at 290-400 nm. Growth and toxin production were examined for five isolates of A. carbonarius and two of A. niger on solid medium simulating juice at early veraison, within the range 0.98-0.92 aw, and at 15 °C, 25 °C, 30 °C and 35 °C. Maximum growth for A. carbonarius and A. niger occurred at ca 0.965 aw / 30 °C and ca 0.98 aw / 35 °C, respectively. The optimum temperature for OA production was 15 °C and little was produced above 25 °C. The optimum aw for toxin production was 0.95 for A. niger and 0.95-0.98 for A. carbonarius. Toxin was produced in young colonies, however, levels were reduced as colonies aged. Black Aspergillus spp. were more commonly isolated from the surface than from the pulp of berries, and increased with berry maturity, or damage. A. niger was isolated more frequently than A. carbonarius and A. aculeatus. Populations of A. carbonarius inoculated onto bunches of Chardonnay and Shiraz decreased from pre-bunch closure to early veraison. Populations from veraison to harvest were variable, and ncreased in bunches with tight clustering and splitting. In a trial with Semillon bunches, omitting fungicide sprays after flowering did not increase the development of Aspergillus rot. Inoculation of bunches with A. carbonarius spore suspension did not necessarily result in Aspergillus bunch rot. In vitro trials suggested that the severity of rot was mediated primarily by the degree of berry damage, followed by the extent of spore coverage. No clear trends regarding cultivar susceptibility were observed. For Semillon bunches inoculated with A. carbonarius spores with and without berry puncture, increased susceptibility to rot and OA formation was associated with berry damage, in particular at greater than 12.3 °Brix (20 d before harvest). OA contamination of bunches was related to the number of mouldy berries per bunch, with shrivelled, severely mouldy berries the primary source of OA. Puncture-inoculation of white grapes (Chardonnay and Semillon) and red grapes (Shiraz) on the vine with A. carbonarius resulted in berries containing OA. Inoculated grapes displayed greater total soluble solids due to berry shrivelling, and greater titratable acidity due to production of citric acid by the fungus. Samples taken throughout vinification of these grapes were analysed for OA. Pressing resulted in the greatest reduction in OA (68-85% decrease in concentration, compared with that of crushed grapes). Additional reductions occurred at racking from grape and gross lees, and after storage. OA was removed by binding to marc, grape and gross lees. Pectolytic enzyme treatment of white must, bentonite juice fining, recovery of juice or wine from lees, and static or rotary style fermentation of red must, had no effect on OA contamination. Bentonite in white wine (containing 56 mg/L grape-derived proteins) and yeast hulls in red wine were effective fining agents for removing OA. Findings from these studies may contribute to the improvement of strategies to minimise OA in Australian wine and dried vine fruit.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture and Wine, 2005.

碩士
國立臺東大學
生命科學系碩士班
104
Sugar apple (Annona squamosa L.) is of economic importance in Taitung. There is a strong consumer demand for ripe fruits due to its special aroma and sweetness. Sugar apple is belong to climacteric fruit, preservation and process are not easy, and fairly sensitive to temperature. It well growers economic losses. Beverage fermented and therefore develop high economic value processing methods its necessity. Yeast plays an important role in brewing, for flavor, aroma and quality of the whole wine have a decisive impact. The study screened wine yeast and explore sugar apple wine optimum fermentation conditions for the use of response surface methodology (RSM). Consists of spontaneous fermentation musts yeast screened was 91, of which 22 have a higher gas production rate (> 7 mL / h) and high alcohol tolerance (> 11%). After strain identification, we obtained five of Saccharomyces cerevisiae, contain Y006, Y057, Y065, Y071 and Y091. Especially, S. cerevisiae Y006 has fastest rate of fermentation and alcohol production, so this study S. cerevisiae Y006 as sugar apple wine fermentation strain. RSM based on a Box-Behnken design was employed to optimize the conditions for sugar apple wine and study the interaction on substrate concentration, initial brix, and fermentation temperature on sugar apple wine alcohol, fermentation cost and methanol. The results of the quadratic model equation showed that the substrate concentration, initial brix, and fermentation temperature have highly significant (p < 0.05) interaction on sugar apple wine alcohol yield, fermentation cost, methanol. It had maximum alcohol yield and minmum fermentation cost and methanol during the initial brix 24 oBrix. The results showed that the optimum conditions of sugar apple wine were found in initial brix 24 oBrix and 27.5% substrate concentration at 27.5℃ fermentation temperature. Fresh sugar apple wine soluble solid 10 oBrix, pH 3.72, 12.7% (v/v) alcohol, 0.34% titratable acidity (as malic acid), 82.6 mg/L methanol, 344 mg/L total phenol, 0.1 browning and 1.14 A420/A520. The appearance is golden brown and with special fruit. It is similar to fermentation cost of sugar apple wine of the small scale fermentation and large scale fermentation. Per liter cost of 91 NTD. In this study, fermentation conditions has the potential to enlarge and have considerable potential for profits and sales and results will be available sugar apple wine industry a new processing options, to reduce production risks. The sensory analysis performed revealed that the produced beverage had good acceptance by the tasters. The overall aspects attribute, which has 64% tasters ‘ liked ’ the beverage.

Aged wine or ‘autolytic’ character is a hallmark in premium sparkling wine usually resulting from traditional method (Méthode Traditionelle) winemaking. Sparkling wine made by this method develops the distinct and desirable flavour and aroma profile and bubbles, attributed to proteolytic processes during prolonged ageing on lees after the secondary fermentation. Intrinsic to this aged wine character is natural enzymatic decomposition of yeast (autolysis) that facilitates the release of compounds into wine that influence wine aroma, flavour and effervescence. The production of high quality sparkling wine is expensive, both in terms of time and physical resources, and there is an opportunity to improve not only the quality of premium sparkling wine but also that of the lower cost sparkling wine options for the consumers, through a combination of traditional practices and innovation. In an effort to introduce ‘autolytic’ character into sparkling wine sooner, microwave, ultrasound or addition of b-glucanase enzymes were applied to yeast to accelerate the disruption of Saccharomyces cerevisiae cell walls. These treated yeasts were added to the tirage liquor during secondary fermentation, and wines analysed at 6 monthly intervals. Treatments applied produced features on yeast that were distinct from that of the untreated control yeast. Whilst control yeast displayed budding cells (growth features) with smooth, cavitated and flat external cell appearances; microwave treated yeast cells exhibited modifications like ‘doughnut’ shapes immediately after treatment (time 0). Similar ‘doughnut’-shaped and ‘pitted/porous’ cell features were observed on progressively older lees from the control. Flow cytometry interpreted alongside the scanning electron microscopy images of yeast revealed bimodal populations of yeast cells with low and high propidium iodide intensities and distinctive ‘doughnut’-shaped cell features observed in association with the microwave treatment only at tirage, that were not observed until 12 months wine ageing in older lees from the control. From a quality perspective, 18 months bottle age was optimum in sparkling wine production on the basis of the influence of yeast treatments added to the tirage solution to effect enhancement of protein concentration, amino acids, polysaccharides and lipids, and the impact of these compounds on sparkling wine foam volume and stability. The microwave and b-glucanase enzymes treatments were associated with a 10 % increase in total free amino acid concentration and a 10 % increase in proline content between 6 months and 18 months bottle age in Chardonnay/Pinot noir blend sparkling wines, confirming disruption effects observed in the visualisation studies. Microwave treatment was associated with elevated asparagine content at 18 months bottle age. The b-glucanase enzymes and ultrasound treatments were associated with significant accumulation of total lipids, that were driven by 2-fold increases in the phospholipids and monoacylglycerol components, respectively, in wine at 18 months bottle age and further the microwave treatment was associated with significantly elevated triacylglycerol at 18 months bottle age. General responses to wine ageing included 60 % higher total phenolic concentration of older sparkling wines than younger wines, and increased total protein concentration from 6 months to 12 months bottle age. In monovarietal sparkling wine production, Chardonnay wines yielded 4-fold higher total protein concentration compared to Pinot noir wines. Total protein concentrations decreased by 40 % in both Chardonnay and Pinot noir sparkling wines from 18 months to 24 months bottle age. Microwave treatment or ultrasound treatment enhanced total protein concentrations by 15 % in Pinot noir sparkling wines aged to 18 months on lees compared to 24 months on lees. Storage of Chardonnay wines at 25 °C depleted total protein concentration by 18 % at both 18 months and 24 months bottle age compared to the control wines. The addition of lees recovered from the primary fermentation to Chardonnay base wine depleted total protein concentration by 40 %, and by 50 % in Pinot noir base wine, from 18 months to 24 months bottle age. The b-glucanase enzymes treatment did not affect total protein concentrations in both Chardonnay or Pinot noir wines. Ageing on lees did not increase total polysaccharide concentrations in Chardonnay or Pinot noir sparkling wines, but the polysaccharides composition was influenced by the treatments. The ultrasound treatment facilitated the release of 10 % more total polysaccharide concentration in Pinot noir sparkling wines after 12 months ageing, attributed to yeast breakdown. The microwave treatment decreased total polysaccharide concentration by 15 % in Pinot noir sparkling wines after 24 months ageing. Addition of lees to Chardonnay or Pinot noir base wines enriched total polysaccharide concentration by 20 % after 18 months bottle age. Total polysaccharide concentrations in the wines appeared not to be influenced by wine storage temperature (15 °C or 25 °C). Foam properties were influenced by grape variety, yeast treatments and bottle age. The decrease in total protein concentration in sparkling wine was associated with foam volume variation and increasing foam velocity with increasing time on lees. Foam stability was unchanged irrespective of wine storage temperature (15 °C or 25 °C). The sparkling wines had similar foaming properties, except for the high temperature storage treated wines and ultrasound treated wines in both Chardonnay and Pinot noir varieties. High temperature storage effected the lowest total protein concentration in the wines compared to the rest of the wines, and an associated decrease in average foam lifetime that was related to an increase in foam velocity. The effects of ultrasound treatment resulted in elevated average foam lifetime in Chardonnay wines and elevated foam velocity in Pinot noir wines at 18 months bottle age. This study offered a rapid approach to visualise alterations to yeast morphology and revealed important changes that occur especially when autolysis was accelerated. The work enabled the categorisation and quantification of yeast morphologies associated with the ageing of sparkling wine, providing a better understanding of the mechanisms of yeast lysis in traditional method sparkling wine production. The influence of yeast treatments on wine composition, and effects on sparkling wine foaming provided a better understanding of the interactions of impact compounds affecting foaming properties. Further exploration of microwave, ultrasound or addition of b-glucanase enzymes treatments of yeast is warranted as tools towards accelerated autolysis for elevated concentrations of desirable compounds released into wine, and the optimisation of production processes to improve sparkling wine quality.

This thesis examines the relationship between water and the winemaking industry through an integrated architectural approach to the landscape. The emphasis is on the refinement of water use for vineyard irrigation and wine processing, and the promotion of the value of water by celebrating a productive landscape. The proposition is explored through the design of a winery and its associated grapes to produce the wines.

Кваліфікаційна робота магістра складається з трьох розділів. Об’єктом дослідження є ринок вина України, його стан та перспективи розвитку. У роботі розглядаються теоретичні аспекти економічної сутності поняття кон’юнктури та узагальнення основних етапів її вивчення, визначення послідовності аналізу кон’юктури ринку та виявлення і проаналіз основних підходів щодо прогнозування кон’юктури ринку. Проаналізовано економічну сутність поняття кон’юнктури та узагальнення основних етапів її вивчення, визначено послідовність аналізу кон’юктури ринку та виявилено і проаналізувано основні підходи до прогнозування кон’юктури ринку. Запропоновано прогноз розвитку даного ринку з урахуванням перспектив посилення позицій українських товаровиробників на міжнародному ринку.
Master's qualification work consists of three sections. The object of the research is the Ukrainian wine market, its state and development prospects. The theoretical aspects of the economic essence of the concept of conjuncture and the generalization of the main stages of its study, the determination of the sequence of analysis of the market conjuncture, and the identification and analysis of the main approaches to forecasting the market conjuncture are considered in the paper. The economic essence of the notion of conjuncture and the generalization of the main stages of its study are analyzed, the sequence of analysis of the market conjuncture is determined and the main approaches to forecasting the market conjuncture are identified and analyzed. The forecast of the development of this market is proposed, taking into account the prospects of strengthening the position of Ukrainian producers in the international market.

This thesis deals with the legislation of viticulture and winemaking in the Czech Republic. The main goal of this thesis is to introduce to the readers both, professionals and non-professionals, viticulture and wine law in its full extensity. For this reason, we deeply analyze the Act No. 321/2004 describing viticulture and winemaking as amended by subsequent law. The thesis is composed of seven main chapters. The abbreviations, witch are subsequently used in the work, are defined in the separate chapter. The first part is an introduction to the topic and describes the origin of growing grape-wine and winemaking. The second part deals with the historical development of vineyard and wine law in the Czech Republic. For the sake of clarity, second part is divided into five subsections. The third chapter defines the position of vineyard and wine law in legal system of Czech Republic and characterizes this specific agriculture sector. The fourth part provides a review of written sources of vineyard and wine law. The chapter is hierarchically separated into the categories: international law, EU law and Czech law. Part five is major and it is the most extensive part of this diploma. It deals with the current legislation of viticulture and winemaking in the Czech Republic by Act No. 321/2004 Coll. It...

Volatile sulfur compounds (VSCs) are a key component of wine aroma, contributing both attractive (‘fruity’) and repulsive (‘rotten eggs’) odours. These compounds largely develop in wine by yeast metabolic activity, as yeast consume the sulfur nutrients available in the grape juice and release a range of VSCs. This thesis studies the formation of VSCs by the wine yeast Saccharomyces cerevisiae and its modulation through nutrient supplementation, focusing on organic sulfur nutrient sources- cysteine, glutathione (GSH) and their polyfunctional thiol conjugates. The thesis first objective was to characterise the effect of an organic nutrient preparation on the resultant sulfur aroma composition. Using metabolite profiling we demonstrated two distinct effects; concentration of the ‘fruity’ polyfunctional thiols 3-mercaptohexan-1-ol (3MH) and 3- mercaptohexyl acetate (3MHA), was increased while the concentration of the ‘rotten egg’ aroma compound, hydrogen sulfide (H2S), was decreased. Nutrient supplementation also changed the kinetics of H2S production during fermentation by advancing its onset. Transcriptomic analysis revealed that this was not due to expression changes within the sulfate assimilation pathway, which is known to be a major contributor to H2S production. This is the first genome-wide study aimed to elucidate the cellular factors affecting cysteine catabolism. Foundations laid here support the use of S. cerevisiae as a model organism to study cysteine catabolism and may provide insights into the underlying cause of cysteine accumulation and H2S generation in eukaryotes. In conclusion, this thesis demonstrates the effective use of nutrients supplementation as a means for wine aroma management. Results and techniques obtained here significantly contribute to our understanding of volatile sulfur compounds formation and provide tools that can be implemented in winemaking for better modulation of sulfur aroma compounds in wine.

Dissertação de mestrado em Engenharia Agronómica
Selected strains of non-Saccharomyces can positively contribute to improve red wine colour by the production of stable pigments thanks to the differences in its metabolism. The main aim of this work was to evaluate the influence of sequential fermentations with nonSaccharomyces and S. cerevisiae at two different temperatures on red wine colour and identify the genus of four strains used on the oenological assay by molecular biology techniques. Physical-chemical parameters and anthocyanin profile were analysed on final wines. Molecular biology techniques were used to determine the yeast genus of IPSMA6, R20VL4, 21A110 and 15C6 strains. Nucleotide sequences of these strains were compared with available DNA sequences in GenBank using BLAST. Strain 21A110 and R20VL4 were identify as Hanseniaspora, strain IPSMA6 was identify as Lachancea and strain 15C6 was identify as Metschnikowia. Respecting to the oenological assay, results showed that the yeast specie/strain used in sequential fermentation has substantial influence on the formation of stable compounds. Moreover, the lower temperature during fermentation improved the anthocyanin profile. Yeast selection and its characterization is important to improve the colouring matter of wine and, consequently, wine quality.