Academic literature on the topic 'Acetic acid fermentation'

Acetic acid fermentation is an essential step in producing high-quality vinegar. In this study, the alcoholic medium was used as a seed broth for acetic fermentation using Acetobacter aceti as the inoculum for approximately 7 days at 32℃ to obtain 45.87g/L acetic acid. During the Acetic acid fermentation stage, the content of the total polyphenols decreased first and then increased. Based on amino acid analyzer analysis, pineapple vinegar contains 18 kinds of free amino acids. And the contents of sweet and umami free amino acids are the main free amino acids, followed by bitter amino acids.

This work aimed to study the properties of acetic fermentation bacteria during the acetic fermentation of wine. Attention was focused on the ability of the bacteria to metabolize selected organic substances and their suitability for wine vinegar production. For the production of wine vinegar, white wine of the variety Veltliner Green was used. Three variants were established for this experiment. The first variant was fermented with Gluconobacter oxydans, the second with Acetobacter aceti, and the third variant of vinegar production was carried out by spontaneous fermentation. During the vinegar fermentation, samples were taken at regular 24-hour intervals and subsequently analyzed. The alcohol, acetic, malic, and tartaric acid contents were monitored. The results showed that all variants showed a strong acetic and malic acid increase. Bacteria Acetobacter aceti produced the most acetic acid within nine days (25 g.L-1). This bacterium also produced the most lactic acid (18 g.L-1). Tartaric acid was also produced in all three variants, but not to the same extent as the previous two organic acids. Acetobacter aceti was found to metabolize ethanol more rapidly than Gluconobacter oxydans.

Siwalan (Borassus flabellifer L.) is a palm family that is widely planted in the Tuban area of ​​East Java. Siwalan sap has a relatively high sugar content of about 10-15 g / 100 ml. The sap is obtained by tapping the inflorescences. In general, siwalan sap is used for fresh drinks or alcoholic beverages with maximum storage in 3 days. Based on the sugar content in the sap of siwalan, acetic acid products can be made through fermentation of glucose to ethanol, then the ethanol is fermented into acetic acid. Acetic acid is widely used as a preservative of food and health drinks. The purpose of this research is to study the effect of ethanol fermentation aerobic pH on acetic acid product. Anaerobic fermentation uses saccharomyces cereviceae to produce ethanol, and aerobic fermentation uses acetobacter aceti for acetic acid production. In aerobic ethanol fermentation using pH 3; 3.5; 4 and 5. The concentration of ethanol was analyzed using GC ULTRA Scientific Gas Chromatography, DSQ II detector, and MS 220 column. Acetic acid produced from the aerobic fermentation process was analyzed using an alkalimetric method. Anaerobic fermentation uses Saccharomyces cereviceae with 1-day log phase, while aerobic fermentation uses acetobacter aceti with a 5 day log phase. Aerobic fermentation to produce acetic acid was observed in 5 days to obtained maximum acetic acid concentration, the highest acetic acid concetration is about 2.595 g/l and yield of acetic acid is obtained 0.519% (b/v) at pH 5. Low acetic acid concentration due to low intitial sugar content in siwalan sap.

Background.Not all yeast alcohol dehydrogenase 2 (ADH2) are repressed by glucose, as reported inSaccharomyces cerevisiae.Pichia stipitisADH2 is regulated by oxygen instead of glucose, whereasKluyveromyces marxianusADH2 is regulated by neither glucose nor ethanol. For this reason, ADH2 regulation of yeasts may be species dependent, leading to a different type of expression and fermentation efficiency.Lachancea fermentatiis a highly efficient ethanol producer, fast-growing cells and adapted to fermentation-related stresses such as ethanol and organic acid, but the metabolic information regarding the regulation of glucose and ethanol production is still lacking.Methods.Our investigation started with the stimulation of ADH2 activity fromS. cerevisiaeandL. fermentatiby glucose and ethanol induction in a glucose-repressed medium. The study also embarked on the retrospective analysis of ADH2 genomic and protein level through direct sequencing and sites identification. Based on the sequence generated, we demonstrated ADH2 gene expression highlighting the conserved NAD(P)-binding domain in the context of glucose fermentation and ethanol production.Results.An increase of ADH2 activity was observed in starvedL. fermentati(LfeADH2) andS. cerevisiae(SceADH2) in response to 2% (w/v) glucose induction. These suggest that in the presence of glucose, ADH2 activity was activated instead of being repressed. An induction of 0.5% (v/v) ethanol also increased LfeADH2 activity, promoting ethanol resistance, whereas accumulating acetic acid at a later stage of fermentation stimulated ADH2 activity and enhanced glucose consumption rates. The lack in upper stream activating sequence (UAS) and TATA elements hindered the possibility of Adr1 binding to LfeADH2. Transcription factors such as SP1 and RAP1 observed in LfeADH2 sequence have been implicated in the regulation of many genes including ADH2. In glucose fermentation,L. fermentatiexhibited a bell-shaped ADH2 expression, showing the highest expression when glucose was depleted and ethanol-acetic acid was increased. Meanwhile, S. cerevisiaeshowed a constitutive ADH2 expression throughout the fermentation process.Discussion.ADH2 expression inL. fermentatimay be subjected to changes in the presence of non-fermentative carbon source. The nucleotide sequence showed that ADH2 transcription could be influenced by other transcription genes of glycolysis oriented due to the lack of specific activation sites for Adr1. Our study suggests that if Adr1 is not capable of promoting LfeADH2 activation, the transcription can be controlled by Rap1 and Sp1 due to their inherent roles. Therefore in future, it is interesting to observe ADH2 gene being highly regulated by these potential transcription factors and functioned as a promoter for yeast under high volume of ethanol and organic acids.

ABSTRACT Cocoa fermentations were performed in wooden boxes under the following four experimental regimens: beans naturally fermented with wild microflora; aseptically prepared beans with no inoculum; and beans inoculated with a defined cocktail containing microorganisms at a suitable concentration either at zero time or by using phased additions at appropriate times. The cocktail used consisted of a yeast,Saccharomyces cerevisiae var. chevalieri, two lactic acid bacterial species, Lactobacillus lactis andLactobacillus plantarum, and two acetic acid bacterial species, Acetobacter aceti and Gluconobacter oxydans subsp. suboxydans. The parameters measured were cell counts (for yeasts, filamentous fungi, lactic acid bacteria, acetic acid bacteria, and spore formers, including reisolation and identification of all residual cell types), sugar, ethanol, acetic acid, and lactic acid contents (and contents of other organic acids), pH, and temperature. A cut test for bean quality and a sensorial analysis of chocolate made from the beans were also performed. The natural fermentation mimicked exactly the conditions in 800-kg boxes on farms. The aseptic box remained largely free of microflora throughout the study, and no significant biochemical changes occurred. With the zero-time inoculum the fermentation was almost identical to the natural fermentation. The fermentation with the phased-addition inoculum was similar, but many changes in parameters were slower and less pronounced, which led to a slightly poorer end product. The data show that the nearly 50 common species of microorganisms found in natural fermentations can be replaced by a judicious selection and concentration of members of each physiological group. This is the first report of successful use of a defined, mixed starter culture in such a complex fermentation, and it should lead to chocolate of more reliable and better quality.

Vinegar, composed of various organic acids, amino acids, and volatile compounds, has been newly recognized as a functional food with health benefits. Vinegar is produced through alcoholic fermentation of various raw materials followed by acetic acid fermentation, and detailed processes greatly vary between different vinegar products. This study performed metabolite profiling of various vinegar products using gas chromatography–mass spectrometry to identify metabolites that are specific to vinegar production processes. In particular, seven traditional vinegars that underwent spontaneous and slow alcoholic and acetic acid fermentations were compared to four commercial vinegars that were produced through fast acetic acid fermentation using distilled ethanol. A total of 102 volatile and 78 nonvolatile compounds were detected, and the principal component analysis of metabolites clearly distinguished between the traditional and commercial vinegars. Ten metabolites were identified as specific or significantly different compounds depending on vinegar production processes, most of which had originated from complex microbial metabolism during traditional vinegar fermentation. These process-specific compounds of vinegars may serve as potential biomarkers for fermentation process controls as well as authenticity and quality evaluation.

ABSTRACTSecondary fermentations during the bulk storage of fermented cucumbers can result in spoilage that causes a total loss of the fermented product, at an estimated cost of $6,000 to $15,000 per affected tank. Previous research has suggested that such fermentations are the result of microbiological utilization of lactic acid and the formation of acetic, butyric, and propionic acids. The objectives of this study were to characterize the chemical and environmental conditions associated with secondary cucumber fermentations and to isolate and characterize potential causative microorganisms. Both commercial spoilage samples and laboratory-reproduced secondary fermentations were evaluated. Potential causative agents were isolated based on morphological characteristics. Two yeasts,Pichia manshuricaandIssatchenkia occidentalis, were identified and detected most commonly concomitantly with lactic acid utilization. In the presence of oxygen, yeast metabolic activities lead to lactic acid degradation, a small decline in the redox potential (Eh, Ag/AgCl, 3 M KCl) of the fermentation brines, and an increase in pH to levels at which bacteria other than the lactic acid bacteria responsible for the primary fermentation can grow and produce acetic, butyric, and propionic acids. Inhibition of these yeasts by allyl isothiocyanate (AITC) resulted in stabilization of the fermented medium, while the absence of the preservative resulted in the disappearance of lactic and acetic acids in a model system. Additionally, three Gram-positive bacteria,Lactobacillus buchneri, aClostridiumsp., andPediococcus ethanolidurans, were identified as potentially relevant to different stages of the secondary fermentation. The unique opportunity to study commercial spoilage samples generated a better understanding of the microbiota and environmental conditions associated with secondary cucumber fermentations.

This research is to study the effect of ethanol fermentation aerobic pH on acetic acid product. Anaerobic fermentation uses saccharomyces cerevisiae to produce ethanol, and aerobic fermentation uses acetobacter acetic for acetic acid production. In aerobic ethanol fermentation using pH 3; 3.5; 4 and 5. The ethanol concentration was evaluated using GC ULTRA Scientific Gas Chromatography, DSQ II detector, and MS 220 column. Acetic acid produced was analyzed using an alkalymetric method. Anaerobic fermentation uses Saccharomyces cerevisiae with 1-day log phase, while aerobic fermentation uses acetobacter aceti with a 5-day log phase. Fermentation using saccharomyces cerevisiae within 24 hours so that reduction sugar could stably decrease, optimum ethanol could be got at optimum pH 6 which could decrease 55 % of reducing sugar concentration to produce 8,20583 %v/v ethanol. Fermentation acetate acid content observed in 3 days at pH 6 and 30 ⁰C will produce 6,659 g/l also shows that pH 4-6 at 30 ⁰C will produce 6,605 g/l acetate acid. Aerobic fermentation of acetate acid in 3 days shows that pH 4-6 is highly affected by temperature at 30⁰C. Statistical analysis shows, in ethanol production pH and fermentation time give significant effect, but interaction has no significant effect.

Soybean molasses is a by-product from the production of protein concentrate from soybean meal that predominantly contains sugars, with sucrose as the major component. In Brazil, soybean molasses is used for animal feed or it is discarded, although some industries use it to produce ethanol. This study aims to evaluate the parameters required for the acetic acid fermentation of soybean molasses, and characterise the resultant vinegar. To study the most suitable parameters for the acetic acid fermentation, vinegar was produced from the alcoholic fermentation of soybean molasses through eight fermentation cycles: five for adaptation and three for production. The average acidity of the acetic acid fermentation product was 50.60 g/L, with an acetic acid fermentation yield, total yield of acetic acid in broth and productivity 65.01 %, 92.76 % and 0.033 g/(L·h), respectively. The vinegar produced from soybean molasses had an acidity of 5.07 % (m/V), residual ethanol content 0.17 % (m/V), sugars 7.86 % (m/V), dry extract 14.67 % (m/V), ash 2.27 % (m/V) and a density of 1.023 g/cm3. The contents of total phenolics and isoflavone decreased after the alcohol and acetic acid fermentations. Moreover, the isoflavone profile of the fermented product comprised only three forms: daidzein, glycitin and genistin. According to our results, 3460 L of vinegar can be produced for every tonne of soy molasses, with an acetic acid concentration of 40 g/L, the minimum required by the legislation on vinegar production. Thus, these findings demonstrate that soy molasses represents a useful raw material for the production of vinegar.

ABSTRACTFour cocoa-specific acetic acid bacterium (AAB) strains, namely,Acetobacter pasteurianus386B,Acetobacter ghanensisLMG 23848T,Acetobacter fabarumLMG 24244T, andAcetobacter senegalensis108B, were analyzed kinetically and metabolically during monoculture laboratory fermentations. A cocoa pulp simulation medium (CPSM) for AAB, containing ethanol, lactic acid, and mannitol, was used. All AAB strains differed in their ethanol and lactic acid oxidation kinetics, whereby onlyA. pasteurianus386B performed a fast oxidation of ethanol and lactic acid into acetic acid and acetoin, respectively. OnlyA. pasteurianus386B andA. ghanensisLMG 23848Toxidized mannitol into fructose. Coculture fermentations withA. pasteurianus386B orA. ghanensisLMG 23848TandLactobacillus fermentum222 in CPSM for lactic acid bacteria (LAB) containing glucose, fructose, and citric acid revealed oxidation of lactic acid produced by the LAB strain into acetic acid and acetoin that was faster in the case ofA. pasteurianus386B. A triculture fermentation withSaccharomyces cerevisiaeH5S5K23,L. fermentum222, andA. pasteurianus386B, using CPSM for LAB, showed oxidation of ethanol and lactic acid produced by the yeast and LAB strain, respectively, into acetic acid and acetoin. Hence, acetic acid and acetoin are the major end metabolites of cocoa bean fermentation. All data highlight thatA. pasteurianus386B displayed beneficial functional roles to be used as a starter culture, namely, a fast oxidation of ethanol and lactic acid, and that these metabolites play a key role as substrates forA. pasteurianusin its indispensable cross-feeding interactions with yeast and LAB during cocoa bean fermentation.

Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Dr. Rachel Chen; Committee Member: Dr. Athanassios Sambanis; Committee Member: Dr. Sankar Nair. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Les énergies non-renouvelables ont été d’un apport capital dans l’industrialisation et l’urbanisation dans les derniers centenaires. L’exploitation excessive des réserves d’hydrocarbures et son impact environnemental ont contribué au developpement de plusieurs technologies durables à caractère néo-carbone neutre. A cet effet, les processus biologiques comme la fermentation pourraient être exploités pour convertir biologiquement le hydrates de carbone en énergies comme l’hydrogène (H2) ou des acides organiques commercialement rentables. Ce travail a étudié les techniques d’ingénierie pour améliorer la synthèse simultanée d’H2 et d’acide lactique à travers des conditions de fermentation capnophile lactique (CLF) par une souche de labo de Thermotoga neapolitana.En un premier temps, une comparaison génotypique entre la souche de labo et celle sauvage a révélé une ressemblance de 88,1 (±2,4) %. En plus, les analyses du génotypage par RiboPrint® et par spectroscopie de masse matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF MS) ont montré une différentiation génétique au-delà du niveau sous-espèce ; et par conséquent la souche de labo a été proposée comme sous-espèce, T. neapolitana subsp. lactica. Basé sur la caractérisation phénotypique, la souche de labo produisait 10-90% plus d’acide lactique que celle sauvage sous les mêmes conditions sans pour autant affecté le taux de production d’H2.La souche de labo a donc été étudiée pour aussi bien optimiser les conditions de croissance que pour estimer les paramètres cinétiques de croissance. Un nouveau modèle cinétique basé sur les principes de fermentation à l’obscurité (DF) et les expressions mathématiques Monod ont été développés pour permettre la simulation de la croissance en biomasse, la consommation de substrat, et la formation de produit. Le modèle n’a cependant pas pu faire une estimation des acides acétique et lactique avec précision du fait que le modèle DF n’a pas considéré la carboxylation de l’acide acétique en acide lactique par l’enzyme pyruvate ferrédoxine oxydoréductase (PFOR) sous les conditions CLF.Le model a été associé avec le mécanisme CLF et les paramètres cinétiques ont été recalibrés. Les paramètres cinétiques que sont le taux d’absorption spécifique maximum (k), la constante semi-saturation (ks), le coefficient en rendement biomasse (Y), et le taux de décomposition interne (kd) étaient de 1,30 l/h, 1,42 g/L, 0,12 et 0,02 l/h. Fait intéressant, le nouveau modèle CLF s’est parfaitement adapté avec les résultats expérimentaux et a estimé que près de 40-80% de la production d’acide lactique est attribué au recyclage de l’acide acétique et le CO2.En plus, l’adsorption de l’acide lactique par le carbone actif et les résines polymères anioniques a été appliquée avec succès comme technique de transformation en aval dans la récupération et la purification de l’acide lactique à partir du modèle de fermentation type T. neapolitana. Pour ce faire, ce travail de recherche constitue une étape majeure dans le domaine de la fermentation bactérienne utilisable pour de vastes applications scientifiques prenant en compte le développement d’énergies renouvelables et la production industrielle d’acide lactique
The environmental impact of excessive exploitation of fossil fuel reserves has inspired the innovation of several sustainable neo-carbon-neutral technologies. To that end, the biological processes like fermentation may be leveraged to bioconvert carbohydrate-rich feedstocks to fuels like hydrogen (H2) or commercially valuable organic acids like lactic acid. This research work investigated the engineering techniques for improving simultaneous synthesis of H2 and lactic acid under capnophilic (CO2-dependent) lactic fermentation (CLF) conditions by a lab strain of Thermotoga neapolitana.Primarily, the genotypic comparison between the lab strain and the wild-type revealed DNA homology of 88.1 (± 2.4)%. Genotyping by RiboPrint® and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses showed a genetic differentiation beyond subspecies level, hence the lab strain was proposed as a new subspecies, T. neapolitana subsp. lactica. The lab strain produced 10-90% more lactic acid, based on the phenotypic characterization, than the wild-type strain under similar operating conditions without impairing the H2 yield.The lab strain was then studied to optimize the growth conditions as well as to estimate the growth kinetic parameters. A new mathematical model based on the dark fermentation (DF) principles and Monod-like kinetic expressions was developed to enable the simulation of biomass growth, substrate consumption and product formation. The model failed to estimate acetic and lactic acid accurately, as the DF model did not consider the carboxylation of acetic acid to lactic acid by the pyruvate:ferredoxin oxidoreductase (PFOR) enzyme under CLF conditions. The model was then incorporated with the CLF mechanism and the kinetic parameters were recalibrated.The calibrated kinetic parameters, i.e. maximum specific uptake rate (k), semi-saturation constant (kS), biomass yield coefficient (Y) and endogenous decay rate (kd) were 1.30 1/h, 1.42 g/L, 0.12 and 0.02 1/h, respectively, under CLF conditions. The new CLF-based model fitted very well with the experimental results and estimated that about 40-80% of the lactic acid production is attributed to the recycling of acetic acid and CO2.In addition, the adsorption of lactic acid by activated carbon and anionic polymeric resins was successfully applied as a downstream processing technique for the recovery of lactic acid from a model T. neapolitana fermentation broth. This research work serves as a practical milestone in the field of microbial fermentation with a scope for wider scientific applications, including the development of bio-based renewable energy and industrial lactic acid production

Thesis (MScAgric)--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: The quality of wine is influenced by numerous factors. These factors include the quality of the grapes, winemaking techniques and quality control throughout the winemaking process. It is thus very important that any process leading to the lowering of the quality of the wine be prevented. Evidence in the wine industry shows that bacterial spoilage is still very much a common problem in many wineries. The spoilage of wine by bacteria can lead to amongst other problems, elevated volatile acidity levels, of which only a certain concentration limit in wine is permitted. Usually more than 90% of the volatile acidity of wine consists of acetic acid. Different yeast strains, heterofermentative lactic acid bacteria and acetic acid bacteria (which can all be spoilage microorganisms) can produce acetic acid in high concentrations. It is thus important to be able to prevent the formation of this acid by controling the unwanted growth of these spoilage microorganisms. Acetic acid and other medium chain fatty acids, octanoic- and decanoic acid, can also lead to stuck or sluggish fermentations. A stuck or sluggish fermentation can also lead to wine spoilage, due to sugar remaining in the fermentation which can be utilized by spoilage microorganisms. Acetic- and other fatty acids enter the yeast cell by passive diffussion and releases its proton in the cytoplasm, thereby acidifying the cytoplasm and inhibiting some enzymes. These acids can also work synergistically with ethanol and its inhibitory effect is also dependent on the temperature. Yeast strains can also differ in their resistance to acetic and other medium chain fatty acids and these acids can also influence the growth of lactic acid bacteria. How acetic acid bacteria influence the winemaking process and the used measures to keep these bacteria from spoiling wine have been the subject of very little attention in the past. This was due to the belief that the anaerobic conditions prevailing in wine and the use of sulfur dioxide are enough to control these bacteria, since acetic acid bacteria were always described as being strictly aerobic microorganisms. Recently, some evidence showed that acetic acid bacteria can survive and even overcome the limits that the winemaking process places on its growth. These bacteria are also known to inhibit the yeasts growth and fermentation ability due to the production of acetic acid and other factors. A research programme on the origin of volatile acidity in South African wines had been initiated at the Department of Viticulture and Enology and at the Institute for Wine Biotechnology at the University of Stellenbosch after increases in volatile acidity in different South African wines had been reported. This spurred us to investigate the occurrence of acetic acid bacteria in South African red wine fermentations, which forms part of this study, and to identify the dominant acetic acid bacterial strains. The sulfur dioxide resistance of five representative strains were also determined, as well as the effect of metabolites which were produced by these bacteria on yeast growth and fermentation ability. Our results indicate that acetic acid bacteria can occur in high concentrations in the fresh must and during alcoholic fermentation. In the 1998 harvesting season acetic acid bacteria occurred at 106-107 cfu per ml in the fresh must. In 1999 these numbers were 104-105 cfu/ml. Acetic acid bacteria numbers decreased in 1998 to 102-103 cfulml during fermentation. The survival of these bacteria in 1999 correlated with the pH of the must, as well as sulfur dioxide dosages in the must. In must with a low pH and higher sulfur dioxide the number of acetic acid bacterial numbers decreased more drastically than in the high pH, low sulfur dioxide musts. This was also true for acetic acid bacterial counts during cold soaking of musts, with the number of acetic acid bacteria increasing during the cold soaking period in musts with a high pH. In musts with a low pH and higher S02 dosages acetic acid bacterial counts did not, however, increase during cold soaking. Gluconobacter oxydans dominated in the fresh must with Acetobacter liquefaciens and especially Acetobacter pasteurianus dominating during the fermentation. Different biochemical and physiological tests revealed that 52% of the 115 isolates tested belong to A. pasteurianus. The high occurrence of A. liquefaciens with A. pasteurianus during fermentation showed that the dominant acetic acid bacterial species in South Africa differed from reports from other wine producing countries. The sulfur dioxide resistance of the acetic acid bacteria tested also differed in white grape juice, with a molecular sulfur dioxide concentration of 0.64 mg/I being necessary to eliminate all the acetic acid bacterial strains tested. The A. hansenii strain was found to be the most resistant to sulfur dioxide and G. oxydans the least resistant. The latter strain was eliminated by only 0.05 mg/I molecular sulfur dioxide, while A. hansenii was only eliminated by 0.64 mg/I molecular sulfur dioxide. The A. pasteurianus, A. liquefaciens and A. aceti strains tested displayed varying degrees of resistance to sulfur dioxide. The volatile acidity produced by these bacteria profoundly influenced the growth and fermentation ability of yeast, which led to slow/stuck fermentation. The A. hansenii and A. pasteurianus strains produced the most volatile acidity in grape juice, with up to 4.02 g/I for A. hansenii within 4 days, which led to a stuck alcoholic fermentation. This was, however, prevented by inhibiting or eliminating the acetic acid bacteria with sufficient sulfur dioxide additions prior to yeast inoculation. Compounds produced by acetic acid bacteria can also influence wine quality. Certain organic acids were produced and metabolized by acetic acid bacteria, as well as acetoin. We could not, however, detect any other fatty acids that are inhibitory to yeast (produced by these bacteria). This study clearly showed that acetic acid bacteria could occur during fermentation and that certain winemaking techniques, like the maintenance of a low pH in the must and sulfur dioxide additions can influence the growth and survival of acetic acid bacteria. Acetic acid bacteria also influence both the winemaking process by inhibiting yeast as well as the quality of the wine by producing acetic acid and/or other compounds. This study also shed some light on the occurrence of acetic acid bacterial species in the South African context and could be important in assisting the winemaker, as well as the scientific reseacher, in finding ways to inhibit acetic acid bacteria in the ongoing battle against these spoilage microorganisms of wine.
AFRIKAANSE OPSOMMING: Wynkwaliteit word deur verskillende faktore beinvloed. Dit sluit die druifkwaliteit, wynmaak tegnieke en kwaliteitsbeheer deur die wynmaakproses in. Enige prosesse en faktore wat tot die verlaging in wynkwaliteit kan lei moet dus ten alle koste voorkom word. Die bederf van wyn deur bakterieë kan en is 'n algemene probleem in enige kelder. Bakteriese bederf kan, onder andere, lei tot verhoogte vlugtige suurheid, waarvan 'n sekere konsentrasie limiet in wyn toegelaat word. Asynsuur maak gewoonlik 90% van die vlugtige suurheid uit. Asynsuur kan deur verskillende gisrasse, heterofermantatiewe melksuurbakterieë en asynsuurbakterieë (wat almal wyn kan bederf) gevorm word. Die vorming van asynsuur in wyn kan dus voorkom word deur die ongewenste groei van dié organismes te voorkom. Asynsuur en ander medium ketting vetsure, soos oktanoë- en dekanoësuur, kan ook tot slepende of gestaakte gistings lei. Suiker wat in die wyn agterbly wat In slepende/gestaakte fermentasie ondergaan kan deur bederf bakterieë gebruik word om die wyn te bederf. Ongedissosieerde asynsuur en ander vetsure dring die gissel binne deur passiewe diffussie en stel 'n proton vry in die sitoplasma wat sitoplasma versuur en sekere ensieme inhibeer. Hierdie sure werk ook sinergisties met etanol en hul inhiberede effek is ook temperatuur afhanklik. Gisrasse verskil in hul weerstandbiedendheid teen asynsuur- en ander mediumketting vetsure en dié vetsure kan ook melksuurbakterieë se groei beïnvloed. Hoe asynsuurbakterieë wyn bederf en die aksies wat geneem kan word om dit te verhoed is in die verlede nie baie ondrsoek nie. Dit is hoofsaaklik daaraan toe te skryf dat geglo is dat die anaerobiese kondisies in wyn en die gebruik van swaweidioksied die groei van asynsuurbakterieë, wat altyd beskryf is as streng aerobe mikroorganismes, kan beheer. Daar is onlangs aangetoon dat asynsuurbakterieë kan oorleef in wyn en selfs die ongunstige kondisies daarin kan oorkom. Hierdie bakterieë is ook in staat om gisgroei en fermentasie vermoë te inhibeer deur die produksie van asynsuur en ander faktore. In Navorsingsprogram om die oorsprong van verhoogde vlugtige suurheid in Suid-Afrikaanse wyne te bepaal is deur die Departement Wingerd- en Wynkunde en die Instituut vir Wynbiotegnologie van die Universiteit van Stellenbosch geinisieer. Dit het ons aangemoedig om die voorkoms van asynsuurbakterieë in Suid-Afrikaanse rooiwyngistings, wat deel vorm van hierdie ondersoek, en ook die dominante asynsuurbakterie rasse te identifiseer. Die swaweidioksied bestandheid van vyf verteenwoordegende rasse en die effek wat metaboliete wat deur dié bakterieë geproduseer is op gisgroei en gisitingsvermoë is bepaal. Ons resultate bewys dat asynsuurbakterieë teen hoë getalle in vars mos en gedurende alkoholiese gisting kan voorkom. Asynsuurbakterieë het gedurende die 1998 seisoen teen 106-107 kve/ml en in 1999 teen 104-105 kve/ml in die vars mos voorgekom. Gedurende fermentasie het hierdie getalle in die 1998 seisoen gedaal na 102-103 kve/ml. Die oorlewing van hierdie bakterieë het gedurende die 1999 seisoen gekorrelleer met die pH en swaweidioksied konsentrasies van die mos. In die lae pH, hoë swaweidioksied moste het asynsuurbakterie getalle vinniger en meer dramaties gedaal as in die hoë pH, lae swaweidioksied moste. Asynsuurbakterie getalle het dieselfde tendens getoon in moste gedurende dopkontak by lae temperature. In moste met 'n hoë pH het asynsuurbakterie getalle toegeneem gedurende koue dopkontak, terwyl dit nie gebeur het nie in moste met 'n lae pH en hoë swaweidioksied konsentrasies. In die vars mos het Gluconobacter oxydans en gedurende die fermentasie Acetobacter liquefaciens en veral Acetobacter pasteurianus oorheers. Verskillende biochemiese en fisiologiese toetse het bepaal dat 52% van die 115 isolate A. pasteurianus is. Die hoë voorkoms van A. liquefaciens saam met A. pasteurianus gedurende gisting bewys dat die voorkoms en dominansie van asynsuurbakterieë in Suid- Afrika verskil van ander wynproduserende lande. Die swaweidioksied weerstandbiedendheid van die asynsuurbakterieë wat getoets het, het ook verskil, met 0.64 mg/I molekulêre swaweIdioksied nodig om hul almal te elimineer in wit druiwesap. Die A. hansenii en G. oxydans rasse was die mees weerstandbiedend en sensitiefste onderskeidelik ten opsigte van swaweidioksied. Slegs 0.05 mg/I molekulêre swaweidioksied was voldoende om G. oxydans te elimineer, terwyl A. hansenii deur 0.64 mg/I molekulêre swaweidioksied geëlimineer is. Die A. pasteurianus, A. liquefaciens en A. aceti rasse het verskillende swaweidioksied weerstandbiedendheid getoon. Die vlugtige suurheid wat deur dié bakterieë geproduseer is het die groei en gistingvermoë van gis drasties beinvloed, wat tot slepende/gestaakte fermentasies gelei het. Die A. hansenii en A. pasteurianus rasse het die meeste vlugtige suurheid geproduseer, met tot 4.02 g/I geproduseer deur A. hansenii na vier dae se groei, wat tot 'n gestaakte fermentasie gelei het. Dit is egter voorkom deur die asynsuurbakterieë te elimineer deur genoegsame swaweidioksied toevoegings tot die mos voor gisinokulasie te doen. Verbindings wat deur asynsuurbakterieë geproduseer word kan ook wynkwaliteit beinvloed. Sekere anorganiese sure is deur hierdie bakterieë geproduseer, terwyl ander gemetaboliseer is. Asetoïen is geproduseer deur die getoetse asynsuurbakterieë. Ons kon egter nie ander vetsure wat gis inhibeer opspoor nie. (Geproduseer deur die bakterieë). Hierdie studie bewys dat asynsuurbakterieë gedurende alkoholiese fermentasie kan voorkom en dat sekere wynmaaktegnieke, soos die verkryging van moste met 'n lae pH en genoegsame swaweidioksied toevoegings die groei en oorlewing van asynsuurbakterieë kan beivloed. Asynsuurbakterieë kan ook beide die wynmaakproses, deur giste te inhibeer, en die wynkwaliteit beivloed deur die produksie van asynsuur en/of ander verbindings. Hierdie studie het ook kennis oor die voorkoms van asynsuurbakterieë in Suid-Afrikaanse moste verbeter en kan ook as 'n nuttige hulpmiddel dien vir die wynmaker en navorser in die stryd om hierdie bederf organismes van wyn te elimineer.

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2016.
Grape producers and wine makers in South Africa are currently affected by various challenges, which include anti-alcohol lobbies, climate change, over-production in some vintages and the lack of transformation including empowerment in certain sectors of the industry. Climate change and global warming lead to poor quality wine grapes and as a result, poor quality wine. Therefore, there is a need to channel grapes away from normal wine production and provide an alternative source of income for the industry. The overall aim of this study was therefore to provide an alternative outlet for overproduced wine grapes by producing balsamic-styled vinegar (BSV) in South Africa. Balsamic vinegar is different from other vinegars because it is a direct product of grape must and not a downstream or by-product of wine production. Balsamic vinegar entails lower production costs when compared to the production of wine due to the low technological process requirements during production; therefore, this could be an opportunity for small business entrepreneurs with low capital start-up. In addition, balsamic vinegar can command a high price, which is a benefit for grape producers. The primary aim of this investigation was to biochemically analyse a BSV production process in which 5 non-Saccharomyces yeast and 15 acetic acid bacteria (AAB) were used for a multicultural alcoholic-acetous (EtOH-AcOH) fermentation process. To achieve this aim, a fermentation process was designed where the data generated was fitted into kinetic models and the proliferation including the population dynamics of the microbial consortia were studied.

A amora-preta (Rubus sp.) faz parte do grupo das chamadas “pequenas frutas” e apresenta propriedades nutricionais relevantes, como elevados conteúdos de sais minerais, vitaminas e compostos bioativos com atividades biológicas. Tais compostos podem auxiliar na prevenção de doenças cardiovasculares, câncer, retinopatia diabética, doença fibrocística e desordens da visão entre outros males. No entanto, a fruta apresenta estrutura frágil e elevada atividade respiratória o que resulta em vida de prateleira reduzida. Desta forma, é tecnicamente importante o desenvolvimento de produtos derivados que mantenham as propriedades nutricionais e compostos bioativos da fruta. Nesse sentido, o presente trabalho teve como objetivo o aproveitamento tecnológico da amora-preta no desenvolvimento de vinagres através dos processos submerso e lento com ciclos sucessivos de acetificação. Inicialmente foi produzido fermentado alcoólico em biorreator de bancada e na sequência foram produzidos fermentados acéticos em vinagreira de grápia e biorreator de bancada. Na fermentação alcoólica foi empregada cepa industrial de Saccharomyces cerevisae r.f. bayanus e na fermentação acética, cepas selvagens de bactérias ácido-acéticas isoladas de vinagre colonial no município de Pato Branco. No processo de fermentação alcoólica foram observados rendimento de 0,39 g/g, produtividade volumétrica em etanol de 1,77g/Lh e eficiência de 75,5%, bem como elevados conteúdos de polifenóis (983,35 mg GAE/100g e 1.702,52 mg GAE/100g). Nos ciclos sucessivos de acetificação conduzida em vinagreira foi obtida produção média de 51,6 g/L de ácido acético, rendimento em ácido acético de 72,2% e produtividade volumétrica de 0,4 g/Lh. Por outro lado, menores valores de produção média de ácido acético (42,26 g/L) e rendimento (70,2%) foram observados no processo de acetificação conduzido em biorreator de bancada. Elevados conteúdos de polifenólicos, antocianinas e elevada atividade antioxidante foram obervados nos vinagres obtidos em ambos os processos de produção. Os vinagres produzidos a partir de amora-preta podem ser considerados vinagres do tipo gourmet que apresentam potencial funcional e a transformação da fruta em vinagre pode ser uma estratégia de agregação de valor a cadeia produtiva colaborando para disseminação da cultura no Brasil.
Blackberry (Rubus sp) is part of the so-called berries, presenting remarkable nutritional features, such as high content of mineral salts, vitamins and bioactive compounds with biological activity. Such compounds may aid in the prevention of cardiovascular diseases, cancer, diabetic retinopathy, fibrocystic and eye diseases, among others. Nevertheless, blackberry presents a fragile structure and a high respiratory activity, resulting in reduced shelf-life. In this way, it is important, from a technological viewpoint, to develop new products derived from blackberry which preserve the fruit original nutritional quality and bioactive compounds. Thus, the present work aimed at the technological utilization of blackberry for developing vinegar by means of the submerged and the slow processes with successive cycles of acetification. Initially, an alcoholic fermented product was obtained in stirred tank bioreactor. Subsequently, acetic fermented products were obtained either in a grapia (Brazilian ash) vinegar barrel or in a bench bioreactor. In the alcoholic fermentation, an industrial strain of Saccharomyces cerevisiae r.f. bayanus was used. In the acetic fermentation, wild strain of acetic acid bacteria isolated from colonial vinegar from Pato Branco city was used. The alcoholic fermentation presented yield of 0.39 g/g, volumetric productivity of 1.77 g/Lh and efficiency of 75.5%, besides high polyphenol contents (983.35 mg GAE/100g and 1702.52 mg GAE/100g). In the successive acetification cycles performed in grapia barrel, average production of 51.6 g acetic acid/L, yield of 72.2% (as acetic acid) and volumetric productivity of 0.4 g/Lh were observed. On the other hand, the acidification performed in bench bioreactor presented lower values of average production (42.26 g acetic acid/L) and yield (70.2%). High polyphenols and anthocyanins content along with high antioxidant activity were observed in the vinegars obtained by both production processes. Vinegars produced from blackberry can be considered gourmet vinegars with high functional potential. The transformation of blackberry into vinegar might be a strategy of value addition to the production chain, contributing for spreading this culture in Brazil.

Les hybrides Saccharomyces interspécifiques isolés de divers milieux fermentaires, combinent les propriétés de leurs parents, telles que les performances fermentaires de S. cerevisiae et la cryotolérance ou production d’arômes de l’autre parent. C’est le cas des hybrides cryotolérants S. cerevisiae X S. kudriavzevii utilisés dans la fermentation des vins blancs, dont la famille Eg8 présente en plus la capacité de libérer de fortes concentrations en thiols variétaux. Cependant, ces hybrides produisent parfois des quantités excessives d’acide acétique, compromettant la qualité des vins. Ce travail a eu pour objectifs de comprendre les causes environnementales et les bases génétiques de la forte production d’acide acétique des souches de la famille Eg8 et de la réduire par une approche d’évolution dirigée. Nous avons tout d’abord montré, en étudiant les effets combinés de 3 paramètres (température, lipides, sucres) à l’aide d’un plan de Box Behnken que la concentration en lipides module à la fois la production d’acide acétique et la concentration finale en thiols de ces souches. Une étude génomique comparative a ensuite révélé plusieurs facteurs pouvant expliquer la forte production d’acide acétique. La partie S. cerevisiae de ces hybrides a notamment pour origine une levure de voile, dont une caractéristique est de produire plus d’acide acétique que les isolats d’autres origines. Une étude transcriptomique (RNAseq) conduite sur 2 souches produisant différents niveaux d’acide acétique nous a permis de révéler un défaut de régulation du métabolisme lipidique chez la forte productrice par rapport à la faible productrice. Sur la base de ces résultats, nous avons mis en oeuvre une approche d’évolution dirigée pour développer des souches à faible production d’acide acétique. En utilisant la limitation en lipides comme pression de sélection, nous avons obtenu des souches évoluées présentant une production d’acide acétique réduite dans différentes conditions œnologiques, tout en conservant une libération de thiols équivalente. Une de ces souches est actuellement testée à l’échelle pilote
Interspecific Saccharomyces hybrids isolated from various fermental media combine the properties of their parents, such as the fermentative performance of S. cerevisiae and the cryotolerance or aroma production of the other parent. This is the case of cryotolerant S. cerevisiae X S. kudriavzevii hybrids used in the fermentation of white wines, among which the Eg8 family also has the capacity to release high concentrations of varietal thiols. However, these hybrids have the disadvantage of sometimes producing excessive amounts of acetic acid, compromising the quality of the wines. The aim of this work was to understand the environmental causes and genetic bases of the high acetic acid production of the Eg8 family strains and to reduce this production by a directed evolution approach. We first showed, by studying the combined effects of 3 parameters (temperature, lipids, sugars) using a Box Behnken experimental design that the lipid concentration modulates both the production of acetic acid and thiols. A comparative genomic study then revealed several factors that may explain their high acetic acid production. The origin of the S. cerevisiae part of these strains is, for example, a flor yeast, which is known to produce more acetic acid than S. cerevisiae strains of other origins. A transcriptomic study (RNAseq) conducted on two strains producing different levels of acetic acid then revealed a less efficient regulation of lipid metabolism by the high producer compared to the low producer. On the basis of these results, we implemented a directed evolution approach to develop low acetic acid production strains. Using lipid limitation as a selection pressure, we obtained evolved strains with reduced acetic acid production under different oenological conditions, while maintaining equivalent thiol release. One of these strains is currently being tested at pilot scale

La fermentation du cacao est une fermentation spontanée qui dure de 4 à 8 jours et repose principalement sur la succession de trois groupes de microorganismes : les levures, les bactéries lactiques et les bactéries acétiques qui réalisent les fermentations alcoolique, lactique et acétique respectivement. Les fèves saines sont stériles jusqu’à l’ouverture de la cabosse. L’inoculation des fèves est réalisée le plus souvent naturellement à l’aide de l’environnement autour de l’écabossage et de la mise en fermentation. Les procédés de traitements post-récolte sont différents d’un pays à l’autre et influencent le déroulement de la fermentation. Cependant, trois espèces de bactéries lactiques et acétiques (Lactobacillus plantarum, Lactobacillus fermentum et Acetobacter pasteurianus) dominent les fermentations dans tous les pays. Par contre, leur diversité intra spécifique n’a été que rarement étudiée. Dans cette étude nous avons utilisé des méthodes moléculaires indépendantes de la culture (PCR-DGGE et metabarcoding) pour étudier les communautés bactériennes associées à la fermentation des fèves de cacao selon trois pays : le Mexique, la Côte d’Ivoire et la Guyane. La méthode de metabarcoding a également été utilisée pour identifier la contribution des surfaces liées à l’environnement pré et post récolte des cabosses de cacao lors d’une fermentation réalisée au Mexique. La dominance des genres Lactobacillus et Acetobacter au cours de la fermentation dans chaque pays a été confirmée. De plus, la présence de genres spécifiques à chaque pays a été mise en évidence lors du premier jour de la fermentation. L’ensemble des surfaces lié à l’environnement de la fermentation semble participer à l’inoculation des genres dominants. Elles agissent en tant que réservoirs bactériens. Une collection de souches de bactéries lactiques et acétiques a été constituée. L. plantarum et A. pasteurianus ont été les deux espèces isolées en majorité. La diversité intra spécifique des souches d’A. pasteurianus a été étudiée. Pour cela, leurs polymorphismes génomiques ont été analysés à l’aide d’une amplification par PCR sur des séquences répétées et leurs caractéristiques biochimiques ont été comparées dans un milieu simulant les conditions de la pulpe de cacao au 2ème jour de fermentation. Notre étude a contribué à montrer que les mêmes souches d’A. pasteurianus peuvent être présentes dans les 3 pays différents. Certaines souches se distinguent pour leur plus grande affinité pour l’acide lactique que les autres, ce qui est intéressant pour améliorer la qualité organoleptique du cacao final. Les résultats sur la diversité intra spécifique nous permettent de proposer des candidats potentiels pour l’élaboration de starters de culture pour la fermentation des fèves de cacao
Cocoa fermentation is a spontaneous fermentation that lasts 4 to 8 days. It is mainly based on the succession of three groups of microorganisms: yeasts, lactic acid bacteria and acetic bacteria that carry out respectively the alcoholic, lactic and acetic fermentation. The beans are sterile until the opening of the pod. The inoculation of the beans is usually naturally done using the environment around the pod opening and the fermentation process. Post-harvest treatment processes differ from one country to another and influence the fermentation progress. However, three species of lactic and acetic bacteria (L. plantarum, L. fermentum and A. pasteurianus) dominate the fermentations in all countries. On the other hand, their intraspecific diversity was rarely studied. In this study, we used the metabarcoding method to study the interspecific diversity of bacterial communities associated with the fermentation of cocoa beans in 3 countries: Mexico, Ivory Coast and Guyana. In addition, this method was used to identify the contribution of the surfaces related to the pre- and post-harvest environment of cocoa pods during the fermentation, which was carried out in Mexico. The dominance of the genera Lactobacillus and Acetobacter during fermentation in each country has been confirmed. In addition, the presence of country-specific genera was founded on the first day of fermentation. All the surfaces linked to the fermentation environment participate to the inoculation of the dominant genera. They act as bacterial tanks. A collection of lactic and acetic bacteria strains was produced. L. plantarum and A. pasteurianus were the most isolated species. Intra-specific diversity of A. pasteurianus strain was studied. For this, their genomic polymorphisms were analyzed using PCR amplification on repeated sequences and their biochemical characteristics were compared in a specific medium, simulating the conditions of the cocoa pulp at the 2nd day of fermentation. Our study showed that the strains of A. pasteurianus could be present in the three different countries. Some strains were distinguished for their greater affinity for lactic acid than the others, which is interesting in order to improve the organoleptic quality of the final cocoa. The results on intra-specific diversity allow us to propose potential candidates for the production of culture starters for the fermentation of cocoa beans

A ensilagem da cana-de-açúcar sem o controle da produção de etanol resulta em silagens de baixa qualidade, podendo reduzir o consumo voluntário e o desempenho animal. O valor nutritivo de silagens de cana-de-açúcar e seus efeitos sobre o desempenho e o comportamento ingestivo de cabras em lactação e de cordeiros confinados foram avaliados em diferentes ensaios. Trinta e nove cabras da raça Saanen foram utilizadas para avaliar o consumo de matéria seca (CMS), a produção e composição do leite, os componentes sangüíneos e o comportamento ingestivo. Trinta cordeiros da raça Santa Inês foram confinados para avaliar o desempenho, as características da carcaça e o comportamento ingestivo. Os animais foram alimentados com rações compostas de 50% de volumoso e 50% de concentrado, diferindo quanto ao tipo do volumoso utilizado: cana-de-açúcar in natura, silagem de cana-de-açúcar sem aditivo e silagem de cana-de-açúcar aditivada com L. buchneri (5x104 ufc/g MV), constituindo os tratamentos experimentais SC, SCS e SCS+Lb, respectivamente. O comportamento ingestivo foi realizado individualmente, com observações feitas a cada cinco minutos. Amostras das silagens foram analisadas para matéria seca (MS), proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), carboidratos solúveis (CHOS), ácido acético e etanol, e as médias foram comparadas com a cana-de-açúcar in natura. A estabilidade aeróbia foi avaliada através do controle da temperatura, pH e perdas de MS das silagens expostas ao ar. Para determinar os coeficientes de digestibilidade e o balanço de nitrogênio das rações utilizadas na avaliação de desempenho, 12 borregos foram mantidos em gaiolas para ensaios de metabolismo. O CMS foi maior (P<0,01) para as cabras que receberam o tratamento SC. Não houve diferença (P>0,05) para a produção de leite e produção de leite corrigida para 3,5% de gordura. Os teores de gordura e de sólidos totais no leite foram maiores para as dietas contendo silagem, sendo superior (P<0,01) para o tratamento SCS+Lb. A concentração plasmática de ácidos graxos não esterificados (AGNE) e o tempo despendido com ruminação (min/g MS) foi maior (P<0,05) para os animais alimentados com as silagens. Não houve diferença (P>0,05) para o CMS, ganho de peso vivo, conversão alimentar e parâmetros de carcaça dos cordeiros. O tempo de ingestão (min/g FDN) e a eficiência de ruminação foram inferiores (P<0,05) nos cordeiros alimetados com silagem de cana-de-açúcar. A ensilagem da cana-de-açúcar resultou em redução (P<0,01) no teor de carboidratos solúveis e aumento (P<0,01) nas concentrações da FDN, FDA, hemicelulose e ácido acético. Os teores de MS, CHOS e ácido acético foram maiores (P<0,01) para o tratamento SCS+Lb. Não houve diferença (P>0,01) no teor de etanol entre as silagens. A silagem aditivada apresentou menores (P<0,05) perdas de MS, manutenção do pH e maior (P<0,05) estabilidade durante o período de avaliação em aerobiose. O consumo e a digestibilidade aparente da FDN, FDA e hemicelulose foram maiores (P<0,05) para a rações contendo silagem.
Sugar cane ensiled without controlling ethanol production results in low quality roughage and may decrease voluntary feed intake and animal performance. Sugar cane silages nutritive value and their effects on performance and ingestive behavior of lactating goats and feedlot lambs were evaluated in different trials. Thirty-nine Saanen does were used to evaluate dry matter intake (DMI), milk yield and composition, blood parameters and ingestive behavior. Thirty Santa Ines ram lambs were penned to evaluate performance, carcass characteristics and ingestive behavior. Animals were fed a 50:50 (concentrate:roughage ratio) total mixed ration, with different roughages: fresh sugar cane, sugarcane silage without additive and sugar cane silage treated with Lactobacillus buchneri (5x104 cfu/g wet basis) corresponding to the experimental treatments SC, SCS and SCS+Lb, respectively. Ingestive behavior was evaluated individually every 5 minutes for 24 h. Silages were sampled and analyzed for dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), soluble carbohydrates (CHOS), acetic acid and ethanol and compared with fresh sugar cane. Aerobic stability was evaluated by controlling the temperature, pH and dry matter losses of silages exposed to air for a period of ten days. To evaluate apparent digestibility and N metabolism of diets used in the performance trials, 12 ram lambs were placed in metabolism crates. DMI was higher (P<0.01) for goats fed SC. Milk production (MP) and fat corrected milk yield were similar (P>0.05). Milk fat and total solids were greater for diets containing silages. Does fed SCS+Lb diet had higher (P<0.01) milk fat content than SCS. NEFA concentration and time spent with rumination (min/g DM) was higher (P<0.05) for animals fed silage diets. There were no differences (P>0.05) on dry matter intake, average daily gain, feed conversion and carcass parameters of the feedlot lambs. Eating time (min/g NDF) and rumination efficiency (g DM/h) were lower (P<0.05) for lambs fed silage diets. Sugar cane silage decreased (P<0.01) soluble carbohydrates concentrations and increased (P<0.01) NDF, ADF, hemicelulose and acetic acid levels. DM, soluble carbohydrates and acetic acid were higher (P<0,01) for SCS+Lb. There was no difference (P>0.01) on ethanol levels between silages. SCS+Lb treatment had lower (P<0.01) dry matter losses, unchanged pH and greater (P<0.05) aerobic stability. NDF, ADF and hemicelulose intakes and apparent digestibility were higher (P<0.05) for silage treatments.

In order to assess the impact of the inoculant "BioStabil Plus" on the ensiling process of alfalfa, the parameters of fermentation quality were analyzed (pH, acetic, butyric, lactic acid, ammonia and water-soluble nitrogen in total nitrogen) and chemical composition of silage (crude protein, crude cellulose, crude fats, nitrogen-free extractives and ash), as well as silage quality assessment (DLG and Zelter). Alfalfa biomass in the beginning of flowering phase was ensiled without additives and with the addition of inoculant. The addition of inoculant showed a decrease in pH, increased production of lactic acid, reduced production of acetic acid, with a favorable ratio of these acids (2-3: 1). The introduction of inoculants resulted in improved fermentation quality, which resulted in better preservation of nutrients, especially for crude proteins, since the use of inoculants also showed a decrease in ammonia nitrogen content compared to control (inoculation - 12.28% NH3-N/ΣN, control - 17.42% NH3-N/ΣN). The general conclusion is that inoculant should be added to alfalfa biomass, for the purpose of optimal production of lactic and acetic acid, as well as obtaining higher nutritional value.

The purpose of this study was to determine the effect of homo- and hetero-fermentative lactic acid bacteria mix on the ensiled lucerne fermentation characteristics and aerobic stability in big bales. The lucerne was ensiled without additives (C) and treated with a mix of bacterial inoculant that contains Lactococcus lactis and Lactobacillus buchneri (50:50) (I). Silage was treated with bacterial inoculant, which significantly increased the total organic acids concentration by 69 %, lactic acid by 92% and acetic acid by 76 %. If the results were compared with the C silage, the inoculation significantly decreased the concentrations of butyric acid by 73 %, ethanol by 53 % and ammonia - N concentration by 33%. Inoculated silage had significantly lowered the yeast count by 59 % and moulds count by 34 %. Compared to the inoculated silage and during the aerobic exposure, the untreated silage maximum temperature was significantly higher (13.9 0C vs 4.6 0C) (P &amp;amp;lt; 0.05). Therefore, the bacterial inoculant improved the quality of fermentation and aerobic stability in lucerne silages.

The article describes the technology of making apple and apple-pear vinegars from natural raw materials. Described is the process of aerobic oxidation occurring in alcoholic fermentation of raw materials in the presence of acetic acid bacteria. The work carried out an organoleptic assessment and comparative analysis of samples of the finished product. Based on this, a conclusion was made about the compliance