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Dissertations / Theses on the topic 'Wine and wine making – Microbiology'

Author: Grafiati

Published: 4 June 2021

Last updated: 30 January 2023

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1

Fundira, Margaret. "Optimization of fermentation processes for the production of indigenous fruit wines (Marula)." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52390.

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Thesis (MSc)--University of Stellenbosch, 2001.<br>ENGLISH ABSTRACT: The importance of indigenous fruit wines is not well researched and documented. There is a need to develop and exploit these valuable food resources through improved production practices, storage, preservation and utilization technologies. The maruia fruit is beneficial in many ways, it can be used for making juice, jam, beer or can be eaten as a whole fruit. The highly nutritive nature of the fruit, its distinctive tropical flavor, its wild occurrence and demand by the local and international communities for the by-pro

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2

Du, Toit Wessel J. "The effect of oxygen on the composition and microbiology of red wine /." Link to the online version, 2006. http://hdl.handle.net/10019/1017.

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Van, der Westhuizen T. J. (Theunes Johannes). "Genetic characterisation and breeding of wine yeasts." Thesis, Stellenbosch : Stellenbosch University, 1990. http://hdl.handle.net/10019.1/68827.

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Thesis (MSc)--Stellenbosch University, 1990.<br>ENGLISH ABSTRACT: To remain competitive in the market place, the South African wine industry will have to direct well-planned yeast strain-development programmes. However, the winemaker can only benefit from the extensive biochemical and molecular information of the yeast cell and the impressive arsenal of genetic techniques available, if the wine industry defines its requirements in genetic terms. The successful application of these genetic and recombinant deoxyribonucleic acid (DNA) techniques in breeding programmes depends on the availa

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Jolly, N. P. (Neil Paul). "Characterisation, evaluation and use of non-Saccharomyces yeast strains isolated from vineyards and must." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49877.

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Dissertation (PhD)--University of Stellenbosch, 2004.<br>ENGLISH ABSTRACT: Wine is the product of a complex biological and biochemical interaction between grapes and different microorganisms (fungi, yeasts, lactic acid bacteria and acetic acid bacteria, as well as the mycoviruses and bacteriophages affecting them) in which yeasts play the most important role regarding the alcoholic (primary) fermentation. These wine-associated yeasts can be divided into Saccharomyces and non-Saccharomyces yeasts. During fermentation, there is a sequence of dominance by the various non-Saccharomyces yeas

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5

Costello, Peter James. "Formation of mousy off-flavour in wine by lactic acid bacteria." Title page, contents and summary only, 1998. http://web4.library.adelaide.edu.au/theses/09AHP/09ahpc841.pdf.

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Bibliography: leaves 200-214. Three structurally related compounds, 2-acetyltetrahydropyridine (ACTPY), 2-ethyltetrahydropyridine (ETPY) and N-heterocycle, 2-acetyl-1-pyrroline (ACPY), were quantified and found to be unique components of mousy wines. 35 lactic acid bacteria (LAB) were screened for the ability to produce mousy off-flavour. In addition to Lactobacillus brevis and L. cellobiosus, a diversity of LAB species, particularly heterofermentative Lactobacillus spp. and Oenococcus oeni exhibited this ability in a range of ethanolic and wine-based media. The substrates and metabolism of mo

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Du, Toit Wessel Johannes. "The effect of oxygen on the composition and microbiology of red wine." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1145.

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Thesis (PhD(Agric) (Viticulture and Oenology))--University of Stellenbosch, 2006.<br>The winemaking process involves different complex chemical and biochemical reactions, which include those of oxygen (O2). Oxygen can come into contact with the wine through various winemaking procedures and can be used by the winemaker to enhance the quality of red wine. In wine, the main substrates for oxidation are phenolic molecules, which form quinones. These can influence the sensory characteristics of the wine. O2 can be used in fresh must to remove oxidisable phenolic molecules through a process c

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7

Du, Plessis Heinrich Wilbur 1975. "The role of lactic acid bacteria in brandy production." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53161.

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Thesis (MSc)--University of Stellenbosch, 2002.<br>ENGLISH ABSTRACT: The presence and growth of lactic acid bacteria (LAB) in wine and their influence on wine quality has received much attention in recent years. Lactic acid bacteria are responsible for conducting malolactic fermentation (MLF) in wine. The benefits associated with malolactic fermentation in terms of deacidification of wine and the contribution to wine flavour and complexity have also recently been the topic of research. It is impossible to describe malolactic fermentation as distinctly desirable or undesirable in terms of

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8

Beh, Ai Lin Chemical Sciences &amp Engineering Faculty of Engineering UNSW. "Investigation of yeasts and yeast-like fungi associated with Australian wine grapes using cultural and molecular methods." Awarded by:University of New South Wales. Chemical Sciences & Engineering, 2007. http://handle.unsw.edu.au/1959.4/40683.

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This thesis presents a systematic investigation ofyeasts associated with wine grapes cultivated in several Australian vineyards during the 2001-2003 vintages. Using a combination of cultural and molecular methods, yeast populations of red (Cabernet sauvignon, Merlot, Tyrian) and white (Sauvignon blanc, Semilion) grape varieties were examined throughout grape cultivation. The yeast-like fungus, Aureobasidium pullulans, was the most prevalent species found on grapes. Various species of Cryptococcus, Rhodotorula and Sporobolomyces were frequently isolated throughout grape maturation. Ripe grapes

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9

Oelofse, Adriaan. "Isolation and characterisation of the antimicrobial peptides produced by acetic acid bacteria." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53479.

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Thesis (MSc)--Stellenbosch University, 2003.<br>ENGLISH ABSTRACT: Wine quality is greatly influenced by the number of microorganisms, which occur throughout the winemaking process. Yeasts are responsible for the alcoholic fermentation, the lactic acid bacteria (LAB) are responsible for malolactic fermentation (MLF), while acetic acid bacteria (AAB) are responsible for converting ethanol to acetic acid. These microorganisms are present on the grapes and in the cellar and these consequently serve as gateways to the fermentation tanks where they will affect the wine quality. However, these

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10

Potgieter, Nydia 1977. "The evaluation of β-glucosidase activity produced by wine-isolated yeasts". Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/53769.

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Thesis (MSc)--University of Stellenbosch, 2004.<br>ENGLISH ABSTRACT: ~-Glucosidases constitute a major group of biologically important enzymes that catalyze the hydrolysis of glycosidic linkages in ~-glucosides, as well as in glycosides that contain only carbohydrate residues, e.g. cellobiose. These enzymes occur in all living kingdoms and perform a variety of functions in organisms ranging from bacteria to highly evolved mammals. Three different types of ~-glucosidases are found in humans, each with its own function: glucocerebrosidase (a deficiency causes Gaucher disease), lactase-phl

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11

Muller, Christo A. "Monitoring the spreading of commercial wine yeasts in the vineyard." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53505.

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Thesis (MSc)--Stellenbosch University, 2003.<br>Full text to be digitised and attached to bibliographic record.<br>ENGLISH ABSTRACT: Traditionally, wine has been produced by the spontaneous fermentation of grape juice by yeast that originate from the grapes and winery equipment. Research has shown that the population composition and dynamics of these yeasts and other microorganisms are very complex. Kloeckera and its anamorph, Hanseniaspora, dominate the yeast population found on the surfaces of grapes, although prevailing Saccharomyces cerevisiae strains complete the fermentation process

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12

Swanepoel, Marinda. "Monitoring the quality control chain from vineyard to wine : an industrial case study." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/1231.

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13

Reid, Vernita Jennilee. "Extracellular acid proteases of wine microorganisms : gene identification, activity characterization and impact on wine." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20322.

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Thesis (MSc)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: Non-Saccharomyces yeasts of oenological origin have previously been associated with spoilage or regarded as undesired yeasts in wine. However, these yeasts have recently come under investigation for their positive contribution towards wine aroma especially when used in sequential or co-inoculated fermentations with Saccharomyces cerevisiae. These yeasts are also known to secrete a number of enzymes that could be applicable in wine biotechnology. Amongst these enzymes are aspartic proteases. The secreted proteases from some

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14

Volschenk, Heinrich. "Characterisation of L-malic acid metabolism in strains of Saccharomyces and the development of a commercial wine yeast strain with an efficient malo-ethanolic pathway." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52728.

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Dissertation (PhD)--University of Stellenbosch, 2002.<br>ENGLISH ABSTRACT: L-Malic and tartaric acid are the most prominent organic acids in wine and playa crucial role in winemaking processes and wine quality, including the organoleptic quality and the physical, biochemical and microbial stability of wine. The production of premium wines depends on the oenologist's skill to accurately adjust wine acidity to obtain the optimum balance with other wine components to produce wine with optimum colour and flavour. Strains of Saccharomyces, in general, rarely degrade L-malic acid completely in

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Mtshali, Phillip Senzo. "Screening and characterisation of wine related enzymes produced by wine associated lactic acid bacteria." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/446.

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Bauer, Rolene. "Strategies for the control of malolactic fermentation : characterisation of Pediocin PD-1 and the gene for the malolactic enzyme from Pediococcus damnosus NCFB 1832." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50106.

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Dissertation (PhD Agric)--University of Stellenbosch, 2004.<br>ENGLISH ABSTRACT: Malolactic fermentation (MLF) is conducted by lactic acid bacteria (LAB) and entails the decarboxylation of L-malate to L-Iactate through a reaction catalysed by the malolactic enzyme (MLE). The consequence of this conversion is a decrease in total acidity. MLF plays a part in microbial stabilisation and due to the metabolic activity of the bacteria the organoleptic profile of the wine is modified. In some wines MLF is considered as spoilage, especially in warm viticultural regions with grapes containing le

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Krieling, Shannon Janine. "An investigation into lactic acid bacteria as a possible cause of bitterness in wine." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53271.

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Thesis (MSc)--Stellenbosch University, 2003.<br>ENGLISH ABSTRACT: Spoilage, be it due to microbial actions, chemical reactions or both, poses a serious threat to the food and beverage industries. Not only can spoilage lead to great economic losses, but it can also cause industries to lose their competitive edge in the economic and consumer market. Considering all the modern technologies and the range of preservation techniques that are available, it is surprising that spoilage is still an economic problem. Wine spoilage due to unpalatable bitterness, and the role of lactic acid bacteria

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Duckitt, Edward. "Investigating the impact of sulphur dioxide on Brettanomyces bruxellensis at a molecular and cellular level." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20104.

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Thesis (MSc)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: The yeast Brettanomyces was isolated from beer in 1904 and associated with wine thereafter. A sporulating form, Dekkera, was discovered later. Brettanomyces bruxellensis produces high levels of volatile phenol off-flavours in wine. Sulphur dioxide (SO2) is the most widely used chemical preservative in wine. Yeasts have several mechanisms to cope with the SO2, namely Ssu1p, a membrane bound SO2 transporter; sulphite reduction, sulphite oxidation and acetaldehyde production. In unfavourable environmental conditions, certain y

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Morgan, Joanne. "Screening, isolation and characterisation of antimicrobial/antifungal peptides produced by lactic acid bacteria isolated from wine." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53582.

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Thesis (MSc)--Stellenbosch University, 2003.<br>Full text to be digitised and attached to bibliographic record.<br>ENGLISH ABSTRACT: Winemaking is an age-old tradition that dates back to as early as 6000 BC. In our modern era there are several insects and microorganisms that pose a threat to the grapevine, the environment and the final wine product. Farmers and winemakers are becoming aware of the threat and the fight against disease, spoilage and/or pathogenic microorganisms is on the rise. Currently, the natural environment is being altered through rural developments, pollution and disa

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20

Ranwedzi, Ntanganedzeni. "Optimization of β-glucosidase activy in recombinant Saccharomyces cerevisiae strains". Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/21731.

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Thesis (MSc)--University of Stellenbosch, 2007.<br>ENGLISH ABSTRACT: Wine is a complex medium. Wine aroma, flavour and colour are important quality factors, but these can be influenced by many factors, such as grape-derived compounds that exist as free volatiles and also as glycosidically bound. The chemical composition of wine is determined by factors such as grape variety, geographic position, viticulture condition, microbial ecology of the grape and the winemaking process. The varietals aroma is determined by both the volatile and the non-volatile compounds, such as monoterpenes, nori

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21

Armstrong, Gareth Owen. "The production of resveratrol by wine yeast." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52557.

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Thesis (MSc)--Stellenbosch University, 2001.<br>ENGLISH ABSTRACT: Grapevine is constantly under attack from a wide variety of pathogens including viruses, bacteria and fungi. In order to ensure survival, the grapevine has developed a vast array of defense mechanisms to combat invading organisms. A key element of this disease resistance is the production of phytoalexins, of which resveratrol is the primary component. The synthesis of resveratrol, together with other structural and biochemical defense mechanisms equips the plant to combat a number of pathogens resulting in the production

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22

Oelofse, Adriaan. "Investigating the role of Brettanomyces and Dekkera during winemaking." Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/1975.

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23

Theron, Louwrens Wiid. "Expression and purification of recombinant extracellular proteases originating from non-Saccharomyces yeasts." Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85704.

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Thesis (MSc)--Stellenbosch University, 2013.<br>ENGLISH ABSTRACT: During wine fermentation, yeasts release extracellular enzymes that significantly impact wine properties. While the extracellular proteins of Saccharomyces cerevisiae have been characterised, those of non-Saccharomyces yeasts remain largely unknown. Most of these enzymes break down sugar polymers or catalyse the liberation of glycosidically-bound molecules. Another category of enzymes of oenological interest is represented by acid proteases that are able to prevent or reduce protein haze, as reported in literature, while s

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Louw, Marli. "Metabolic, genetic and physiological responses to SO2 exposure and nutrient-limiting conditions in Brettanomyces bruxellensis." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86465.

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Thesis (MSc)--Stellenbosch University, 2014.<br>ENGLISH ABSTRACT: Brettanomyces bruxellensis has become of increasing interest over the past few decades yet this complex red wine spoilage yeast is still poorly understood and strain variance also leads to the contradictory results reported in literature. This yeast is responsible for the production of phenolic compounds, associated with off-flavours that render wine unpalatable. Sulphur dioxide (SO2) is the most commonly used antioxidant and antimicrobial preservative instrumental in the control of spoilage yeasts such as B. bruxellensis. Howev

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Smit, Annel. "Engineering yeast for the production of optimal levels of volatile phenols in wine." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52823.

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Thesis (MSc)--University of Stellenbosch, 2002.<br>ENGLISH ABSTRACT: Phenolic acids (principally p-coumaric and ferulic acids), which are generally esterified with tartaric acid, are natural constituents of grape must and wine, and can be released as free acids during the winemaking process by certain cinnamoyl esterase activities. Free phenolic acids can be metabolised into 4-vinyl and 4-ethyl derivatives by several microorganisms present in wine. These volatile phenols contribute to the aroma of the wine. The Bretfanomyces yeasts are well known for their ability to form volatile phenol

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Wilcox, Dale Adrian. "Optimization and evaluation of heterologous lysozyme production in saccharomyces cerevisiae." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6690.

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Thesis (MSc)--University of Stellenbosch, 2011.<br>ENGLISH ABSTRACT: Hen egg white lysozyme (HEWL; muramidase; EC 3:2:1:17) is an enzyme present in high concentrations in chicken (Gallus gallus) egg whites. It hydrolyses the link between N-acetylmuramic acid and N-acetylglucosamine in Gram positive bacterial cell walls, resulting in cell death. It is thus active against lactic acid bacteria (LAB), which may be present in grape juices and musts. These bacteria are responsible for malolactic fermentation of wines although many species, particularly of the genera Lactobacillus and Pediococc

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Downing, Lynn 1978. "Characterisation of biogenic amine genes in lactic acid bacteria isolated from wine." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53328.

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Thesis (MSc)--Stellenbosch University, 2003.<br>ENGLISH ABSTRACT: The winemaking process involves a complex microbial flora where the interaction of yeasts, lactic acid bacteria and acetic acid bacteria play an important role in the quality and wholesomeness of the final product. Yeasts are primarily responsible for alcoholic fermentation. Malolactic fermentation follows alcoholic fermentation and is conducted by lactic acid bacteria. These bacteria are important in winemaking and can have a positive or negative effect on the wine quality. Biogenic amines are one of the compounds produc

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Botha, Janita J. "Sensory, chemical and consumer analysis of Brettanomyces spoilage in South African wines." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4141.

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Thesis (MSc Food Sc (Food Science))--University of Stellenbosch, 2010.<br>ENGLISH ABSTRACT: This study focussed on the sensory effects of the main volatile compounds produced by Brettanomyces yeast causing spoilage in wine. This research firstly aimed to determine the detection thresholds of eight Brett-related spoilage compounds in wine. The second aim was to determine the sensory effect of the four most important Brett-related compounds when present individually in wine. The third aim was to determine the sensory effects of these four compounds when present in wine in a range of combina

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Mocke, Bernard A. "The breeding of yeast strains for novel oenological outcomes." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1117.

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Rossouw, Debra. "Comparative 'omic' profiling of industrial wine yeast strains." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1454.

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Thesis (PhD(Agric) Viticulture and Oenology. Wine Biotechnology))--University of Stellenbosch, 2009.<br>The main goal of this project was to elucidate the underlying genetic factors responsible for the different fermentation phenotypes and physiological adaptations of industrial wine yeast strains. To address this problem an ‘omic’ approach was pursued: Five industrial wine yeast strains, namely VIN13, EC1118, BM45, 285 and DV10, were subjected to transcriptional, proteomic and exometabolomic profiling during alcoholic fermentation in simulated wine-making conditions. The aim was to evalu

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Smit, Anita Yolandi. "Evaluating the influence of winemaking practices on biogenic amine production by wine microorganisms." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/1212.

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Mehlomakulu, Ngwekazi Nwabisa. "Genetic investigation and characterization of killer toxins secreted by non-Saccharomyces yeasts." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97035.

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Thesis (PhD)--Stellenbosch University, 2015.<br>ENGLISH ABSTRACT: In the current study, two isolates showing killer activity against several wine yeast species in a previous study were identified to strain level and found to belong to the yeast species Candida pyralidae. The identified yeast strains and a Kluyveromyces wickerhamii yeast strain used as a control exhibited killer activity against B. bruxellensis known for its spoilage characteristics in red wine, and against several strains of the genus Brettanomyces on white and red grape juice medium. The killer yeasts inhibited neither t

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Magerman, Cynthia M. "The evaluation of Fourier transform infrared (FT-IR) spectroscopy for quantitative and qualitative monitoring of alcoholic wine fermentation." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2754.

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Thesis (MSc (Wine Biotechnology))--University of Stellenbosch, 2009.<br>ENGLISH ABSTRACT: Fermentation is a complex process in which raw materials are transformed into high-value products, in this case, grape juice into wine. In this modern and economically competitive society, it is increasingly important to consistently produce wine to definable specifications and styles. Process management throughout the production stage is therefore crucial to achieve effective control over the process and consistent wine quality. Problematic wine fermentations directly impact on cellar productivity a

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Mocke, Leanie. "Kinetic modelling of wine fermentations : why does yeast prefer glucose to fructose." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80316.

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Thesis (MSc)--Stellenbosch University, 2013.<br>ENGLISH ABSTRACT: In the present-day competitive global market, wine industries are constantly aiming to improve the wine-making process,including the role of yeast. The most commonly used wine yeast is Saccharomyces cerevisiae, which is able to produce high quality wines, but problem fermentations do sometimes arise. The occurrence of stuck and sluggish fermentations pose a serious problem leading to loss of productivity and quality. Although the precise mechanism leading to stuck fermentations is unknown, they are often correlated with h

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Ferreira, Jacques. "Factors influencing the fermentation performance of commercial wine yeasts." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16322.

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Thesis (MScAgric)--University of Stellenbosch, 2004.<br>ENGLISH ABSTRACT: The production of quality wine is influenced by numerous factors of which grape quality is one of the most important factors. The production of quality wine, however, is not possible without good winemaking techniques and effective quality control. Critical control points (CCP) during the winemaking process must be identified to ensure optimum wine quality. Grape must is a complex medium that contains different micro-organisms which can be either beneficial or negative to wine quality, depending on the physical and

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De, Klerk Daniel. "Co-expression of aroma liberating enzymes in a wine yeast strain." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1888.

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Thesis (Msc (Viticulture and Oenology. Institute for Wine Biotechnology))--University of Stellenbosch, 2009.<br>Monoterpenes are important aroma compounds in certain grape varieties such as Muscat, Gewürztraminer and Riesling and are present as either odourless, glycosidically bound complexes or as free aromatic monoterpenes. These complexes occur as monoglucosides or, when present as diglycosides, most commonly as 6-O-α-L-arabinofuranosyl-β-D-glucopyranosides of mainly linalool, geraniol, nerol and citronellol. The release of monoterpenes from non-volatile glycosidically bound precursors occ

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Reffatti, Leonardo. "Diferenciação da origem geográfica de vinhos elaborados com uvas de três regiões vitícolas de Santa Catarina através de análises isotópicas e elementos minerais." reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/2443.

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A origem e a tipicidade dos vinhos são temas importantes e de grande interesse para produtores, consumidores e comerciantes. Ambos estão ligados à obtenção de um reconhecimento deste produto perante o mercado consumidor. O Brasil apresenta dimensões continentais e uma ampla diversidade de regiões produtoras de uvas e vinhos, em cada uma encontra-se características peculiares. Santa Catarina é o quarto estado brasileiro em área plantada com videiras no Brasil, apesar disso, é o segundo maior estado produtor de vinhos, apresentando grande potencial para vitivinicultura. Neste estudo coletou-se a

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Du, Toit Wessel J. (Wessel Johannes). "Sources of acetic and other fatty acids and their role in sluggish and stuck red wine fermentations." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51915.

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Thesis (MScAgric)--University of Stellenbosch, 2000.<br>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

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Erasmus, Daniel J. "Deletion analysis of the Ure2p in Saccharomyces cerevisiae and effect of NCR on the production of ethyl carbamate during wine fermentations." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51671.

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Thesis (MSc)--University of Stellenbosch, 2000.<br>ENGLISH ABSTRACT: The wine yeast Saccharomyces cerevisiae has the ability to utilize several different nitrogenous compounds to fulfill its metabolic requirements. Based upon different growth rates of the yeast in a particular nitrogen source, nitrogen compounds have been classified as either good or poor nitrogen sources. In an environment which contains different quality nitrogen sources, such as grape must, the yeast first utilizes good and then the poor nitrogen sources. This discrimination between good and poor nitrogen sources is

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Bauer, Rolene. "Acolein in wine : bacterial origin and analytical detection." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5358.

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Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010.<br>ENGLISH ABSTRACT: Wine quality is compromised by the presence of 3-hydroxypropionaldehyde (3-HPA) due to spontaneous conversion into acrolein under wine making conditions. Acrolein is highly toxic and is presence has been correlated with the development of bitterness in wine. Lactic acid bacterial strains isolated from South African red wine, Lactobacillus pentosus and Lactobacillus brevis, are implicated in accumulating 3- HPA during anaerobic glycerol fermentation. The environmental conditions leading

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Van, der Merwe Hanneli. "The evaluation of malolactic fermentation starter cultures under South African winemaking conditions." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/21913.

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Thesis (MSc)--Stellenbosch University, 2007.<br>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 c

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Knoll, Caroline. "Investigation of bacteriocins from lactic acid bacteria and their impact in winemaking." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/2623.

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Thesis (MSc (Wine Biotechnology))--University of Stellenbosch, 2007.<br>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 tot

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Thanvanthri, Gururajan Vasudevan. "Enhancing xylose utilisation during fermentation by engineering recombinant Saccharomyces cerevisiae strains." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/18705.

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Dissertation (DPhil)--University of Stellenbosch, 2007.<br>ENGLISH ABSTRACT: Xylose is the second most abundant sugar present in plant biomass. Plant biomass is the only potential renewable and sustainable source of energy available to mankind at present, especially in the production of transportation fuels. Transportation fuels such as gasoline can be blended with or completely replaced by ethanol produced exclusively from plant biomass, known as bio-ethanol. Bio-ethanol has the potential to reduce carbon emissions and also the dependence on foreign oil (mostly from the Middle East and

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Fredericks, Ilse Nadia. "Efficacy of ultraviolet radiation as an alternative to inactive technology to inactivate micro organisms in grape juice and wines." Thesis, Cape Peninsula University of Technology, 2010. http://hdl.handle.net/20.500.11838/2022.

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Thesis (MTech (Food Technology))--Cape Peninsula University of Technology, 2010.<br>Sulphiting is considered as the most reliable and understood preservation technique in the wine industry. Since sulphur dioxide (S02) has been associated with possible health risks, legislation as well as consumers, are becoming more reluctant about the general use of S02 in wine production. In order to avoid economic losses due to spoilage, the wine industry is seeking feasible techniques to possibly reduce the levels of S02 in wine. The purpose of this study was, therefore to determine the efficacy of u

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Nel, Hannes Augustinus. "Fermentation optimization of pediocin PD-1 production and a comparative study of the effect of pediocin PD-1, plantaricin 423 and nisin on biofilms of Oenococcus oeni." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52272.

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Thesis (MSc)--Stellenbosch University, 2001.<br>ENGLISH ABSTRACT: Lactic acid bacteria are present in many foods and beverages and are used as starter cultures in the production of a variety of fermented products. Many of these bacteria produce ribosomally synthesized antimicrobial peptides (bacteriocins), which inhibit the growth of bacteria genetically closely related to the producer cell. Since many of these target bacteria include foodbome pathogens such as Bacillus spp., Clostridium spp., Listeria spp., and Staphylococcus spp., the practical importance of these peptides as food prese

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Hutchinson, Ucrecia Faith. "Non-saccharomyces yeast and acetic acid bacteria in balsamic-styled vinegar production : a biochemical process analysis." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2484.

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Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2016.<br>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.

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Malherbe, Daniel Francois. "Expression of the Aspergillus niger glucose oxidase gene in Saccharomyces cerevisiae." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52840.

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Thesis (MSc)--Stellenbosch University, 2002.<br>Full text to be digitised and attached to bibliographic record.<br>ENGLISH ABSTRACT: The winemaking process constitutes a unique ecological niche that involves the interaction of yeasts, lactic acid bacteria and acetic acid bacteria. Saccharomyces cerevisiae has established its importance as a wine yeast and also proven itself as a reliable starter culture organism. Its primary role is to convert the grape sugar into alcohol and, secondly, its metabolic activities result in the production of higher alcohols, fatty acids and esters, which are

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Trollope, Kim. "Investigation of resveratrol production by genetically engineered Saccharomyces cerevisiae strains." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/2230.

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Thesis (MSc (Wine Biotechnology))--University of Stellenbosch, 2006.<br>Resveratrol is a phytoalexin that is produced in the leaves and skins of grape berries in response to biotic and abiotic factors. Substitution and polymerisation of resveratrol units produce an array of compounds which form part of the active disease defence mechanism in grapevine. Wine is one of the major sources of resveratrol in the human diet. Resveratrol is one of the phenolic compounds present in wine that mediates protective effects on human health. It has been shown to prevent the development of cardiovascular dis

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Siebrits, Leoni. "PCR-based DGGE identification of bacteria and yeasts present in South African grape must and wine." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/19865.

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Thesis (MSc)--University of Stellenbosch, 2007.<br>ENGLISH ABSTRACT: Wine production involves complex interactions between a variety of yeasts and bacteria. Conventional microbiological methods can be used to identify the different microorganisms present in wine, but prove to be time-consuming and certain microbial species may not grow on synthetic isolation media. The aim of this study was to evaluate the microbial population present in two South African red wines, Pinotage and Merlot, as well as five spoilt commercial South African wines by using a non-culturable approach, polymerase chain r

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Larentis, Bruno Zorrer. "Sistematização do APPCC para uso nas vinícolas : o caso do vinho merlot da vinícola Larentis." reponame:Repositório Institucional da UCS, 2014. https://repositorio.ucs.br/handle/11338/825.

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Este trabalho apresenta um estudo de caso para aplicação do sistema de Análise de Perigos e Pontos Críticos de Controle no setor vitivinícola, levando em conta as várias etapas de elaboração presentes no processo, bem como todos os cuidados e avaliações necessárias. Trata-se de um método que prevê uma avaliação técnica de produtos. Seu objetivo, em relação ao vinho, é detectar possíveis pontos de contaminação e controlá-los, levando-se em conta todos os agentes envolvidos nesse procedimento. Por isso sua implementação segue regras baseadas em pesquisas. Seguir em detalhes seus fundamentos gara

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