Thesis deals with problems in legal as well as non legal regulations of alcohol usage in Czech Republic. I analyse the development of laws and current version of legal regulations on alcohol availability for young people in Czech Republic. I compare the Czech legislative to legislative in other countries. I analyse different approach to alcohol drinking in varied societies. During work on the diploma thesis, the Czech government declared a prohibition on alcohol trade. I evaluate the Czech approach and compare this prohibition with prohibitions in other countries. Finally, I evaluate Czech regulations of alcohol advertisments, and describe several court decisions (and self-regulatory board decisions) in alcohol advertising. The aim of thesis is to find the positive and negative aspects of legal and non-legal regulations in individual countries and propose new solutions to current alcohol problems.

M. Tech. (Department of Biotechnology, Faculty of Applied and Computer Sciences), Vaal University of Technology. / Obesity has steadily increased and represents a major public health problem worldwide, reducing quality of life and causing a range of health problems. Obesity has emerged as the fifth leading risk of global deaths. Annually, 2.8 million adults die as a result of being overweight or obese. The increase of obesity remains inexplicable in terms of genetic susceptibility to obesity. The genetic loci identified by genome-wide association studies (GWASs) explains about 2% of the heritability for obesity. Perhaps other factors such as epigenetics may be involved in the increase of obesity and may offer solutions for the management of obesity. Epigenetics is defined as a heritable change in gene expression without altering the genome sequences. It may help in providing a logical explanation between the genome and environment which shapes obesity risk and may help to explain the "missing heritability". Epigenetics may affect two mechanisms, namely: i) DNA methylation,and ii) histone modifications. DNA methylation might give scientists a link to the rise in obesity.The study aimed to investigate the effect of sugars used as sweeteners in sugar-sweetened beverages (SSB) on DNA methylation in a Caco-2 cell line in vitro. Four major objectives were pursued in the study which were to:(1) stimulate the Caco-2 cells with varying concentrations of sugar sweeteners and assess the morphological changes of the cells; (2) evaluate the cytotoxicity of different concentrations of the sugar sweetener on the Caco-2 cell line using the Alamar blue and LDH assay; (3) obtain genomic DNA from the treated Caco-2 cell line and perform bisulfite conversion and rest; and (4) amplify the WT1, MEG3, TNFRSF9, ATP10A, and CD44 obesity-associated genes and ascertain their degree of methylation. Caco-2 cells were stimulated with sugar sweeteners at varying concentrations (low, medium and high) for an incubation period of 62 days,and images of the cells were captured for morphological characterisation. The incubation condition entailed cells plated in a 12 or 96 well plate, incubated in a humidified 5% CO2 incubator at 37 °C and there is nutrient renewal every three days.Alamar blue, a cell proliferation colourimetric assay and lactate dehydrogenase assays (LDH), a homogenous membrane fluorimetric assay were used for the cytotoxicity studies. The results of the characterisation showed that different concentrations of sugar sweeteners affected the morphology of the cells as the incubation period progressed. The cytotoxicity results of both LDH and Alamar blue depicted low concentration of sweeteners that had low-to-moderate toxicity and the medium and high concentration of the sweeteners had a moderate to high toxicity on the Caco-2 cells. DNA from the Caco-2 cells was extracted. Techniques used to study DNA methylation such as bisulfite conversion, PCR amplification and restriction enzymes that have differential sensitivity to 5-methyl-cytosine were performed. The quality of DNA extracted was good. The bisulfite conversion was conducted andno amplification was observed, as a contingency plan Normal PCR was performed to amplify the CpG islands, and there was amplification. In conclusion, the study showed that a low concentration of a sugar sweetener (fructose: glucose) used in beverages had low toxicity to the Caco-2 cell line and prolonged exposure of the low concentration might have an adverse effect on the cells' morphology. At medium concentrations, the sugar sweetener used in beverages had medium toxicity to Caco-2 cells; prolonged exposure may lead to morphological changes. These findings indicated that control of dietary glucose intake is an important strategy in combating the development of obesity and type-2 diabetes. DNA methylation could not be established.

Thesis (M. A. (Physiology)) -- University of Limpopo, 2022 / Background: Metabolic syndrome (MetS) is amongst the underlying causes of mortality and morbidity globally. However, lifestyle habits such as frequent consumption of sugar-sweetened beverages (SSBs) contributes to its onset. The study was aimed at investigating the association between MetS and SSBs intake among Ellisras rural youth. Additionally, to find the best obesity indices to predict MetS. Methods: The current study included a total of 593 Ellisras rural youth, aged 22 to 30 years (289 males and 304 females). Anthropometric measurements, blood pressure (BP), and biochemical assessment were taken using standards procedures. A validated 24hrs recall questionnaire and food manuals were used to collect SSBs data. Binary logistic regression was applied to determine the association between SSBs intake and MetS components for the adjusted model. Confirmatory factor analysis was used to test the best single-factor models to predict MetS on commonly selected obesity indices. Results: The SSBs quartile 4 was associated with a high risk of high fasting blood glucose (FBG) for adjusted (OR=2.32; CI=1.15-4.70; p<0.05) and unadjusted (OR=2.34; CI=1.16-4.73; p<0.05) models were a significant linear trend (p for trend=0.049) in males was found. Low risk of reduced high density lipoprotein cholesterol (HDL-C) was associated with the second and fourth SSBs quartiles for unadjusted ((OR=0.40; CI=0.18-0.85; p<0.05; OR=0.37; CI=0.13-0.80; p<0.05) respectively and adjusted model (OR=0.40; CI=0.18-0.85; p<0.05; OR=0.37; CI=0.17-0.80; p<0.05) respectively in females. Moreover, the fourth SSBs quartile was likely to decrease the risk of high triglycerides (TG) for unadjusted (OR=0.12; CI=0.01-0.87; p<0.05) and adjusted (OR=0.10; CI=0.01-0.83; p<0.05) models were the significant linear trend (p= trend 0.006) was observed also in females. There was a significant linear trend association between SSBs quartiles consumption and high TG in males and high waist circumference (WC) in females, but logistic regression analysis didn’t depict any significant association (p>0.05). In males, single model fit built based on WC (comparative fit index (CFI)=1.00; turker lewis index (TLI)=1.05; RMSEA=0.00; akaike information criterion (AIC)=-2680) and waist to height ratio v (WHtR) (RMSEA=0.00, CFI=1.00; AIC=-2662, TLI=1.05;) suggested a better fit index as compared to body mass index (BMI) and neck circumference (NC). Among females, a single model fit built on NC obtained a better fit index (RMSEA=0.05, CFI=0.90, and AIC= -429.21, TLI=0.71). Conclusion: In this study, there was an association between SSBs consumption and some MetS components (high TG, reduced HDL-C, and high FBG). Obesity indices including WHtR, NC, and WC were the best predictors of MetS. Future studies are recommended to further investigate the association of the risk of MetS and the consumption SSBs and the best obesity indices to predict MetS to assist in efforts to help curb MetS and related risk factors in rural areas of South Africa.

Doctor of Philosophy / Department of Agricultural Economics / Vincent R. Amanor-Boadu / This dissertation is composed of two essays in applied microeconomics. Using farm level data, the first essay applied nonparametric methods to test the adherence of individual farm’s production choices to profit maximization objective. Results indicate that none of the farms consistently satisfy the joint hypothesis of profit maximization. The study took into account the uncertainty prevalent in agricultural production by systematically modeling the optimization behavior of farms. Departures of observed data of individual farms from profit maximization objectives were attributed more due to stochastic influences caused by output production decisions than input use decisions. Results also support the existence of technological progress during the study period for Kansas farms. At an alpha level of 5%, assuming both input and output quantities as stochastic, only 5.3% of the farms violated the joint hypothesis of profit maximization with standard error exceeding 10%. Whereas when only input quantities are considered stochastic, a total of 71.73% and 2.09% of the farms had minimum standard errors of greater than 10% and 20% respectively required for the joint profit maximization hypothesis to hold. When only output quantity measurements were assumed as stochastic, a total of 80.10 % and 18.84 % of the farms had minimum standard errors of greater than 10% and 20% respectively required for the profit maximization hypothesis to hold. The second essay examines the demand for alcoholic beverages (beer, wine and distilled spirits) for the U.S. using time series data from 1979-2006. The estimation is done using an error correction form of the Almost Ideal Demand System . Results indicate that there is a significant difference between short run and long run elasticity estimates. The paper addresses the exogeneity of log of prices and log of real expenditures. For the beer and wine equations, the hypothesis of joint exogeneity of price index and real expenditure cannot be rejected at all the conventional levels of significance. For the spirits equation, the tests strongly reject the simultaneous exogeneity of price index and real expenditure. When independently tested, price index appears to be endogenous variable where as real expenditure seems exogenous variable. Based on these results, the real expenditure was considered as an exogenous variable, where as the price index for spirits as an endogenous variable.

Master of Science / Food Science / Delores H. Chambers / Tools are available, through various reference books, to develop a purposeful sensory quality program. Some companies already have a strong sensory program in place; others may require a cultural change to facilitate the implementation. This paper indicates some of the challenges to be overcome, covers some current quality control (QC) sensory practices and addresses advantages and disadvantages of expert tasters Some specific issues regarding sensory evaluations of alcohol beverages are discussed and critical factors in production are reviewed with discussion on the potential for off taint development.

Sin taxes have increased significantly during the past three years. There have been different opinions regarding the levying of sin taxes: in relation to whether it helps the government to raise revenue or reduces the consumption thereof. This study therefore investigates the actual purpose for these taxes by means of a literature and empirical review. An increase in sin taxes affects the poor more than the rich because such taxes are classified as a regressive type of tax. The primary research problem addressed by this literature study was to determine the percentage that the lower income earning group of South African citizens, who are funded by social grants, spend on sin taxed items. This study focused on two areas: the social grant system in conjunction with the Consumer Price Index (“CPI”) and the levying of sin taxes in South Africa. Over the years, South Africa has experienced an increase in its levels of poverty. There are eight types of social grants in South Africa, to which the lower income earning South African citizens, who live below the poverty line, are entitled, depending on their circumstances. This study discusses only seven of the eight social grants, by considering the purpose of the social grant, criteria, means testing requirements and the monthly amount available. These grants include the child support grant, old age grant, disability grant, foster care grant, care dependency grant, grant-in-aid and war veteran grant. The CPI of South Africa is briefly addressed in this study, followed by the increases over the past three years. The escalations of the social grants and that of the CPI of South Africa have been compared in order to determine whether the government remains concerned for their lower income earning citizens most of whom live below the poverty line. For purposes of this study, sin taxes have been narrowed down to include only alcoholic beverages and cigarettes. This study determined the increases of sin taxes on these substances over the past three years as well as the consumption thereof. Their consumption was determined by the sales volume. A comparison of the increases and consumption was made, the purpose of which was to determine government’s motivation for these increases. The empirical review of this study investigated the social grant recipients’ spending habits on these items. This was done by means of a self- developed questionnaire. The purpose of the questionnaire was to determine the percentage of their grant money that the social grant recipients spend on alcoholic beverages and cigarettes. The results and findings led to a conclusion which addressed the problem of this study. This study makes recommendations for further investigation of the sin tax implications for the lower income earning South African citizens, who are funded by social grants. / MCom (Accountancy)--North-West University, Vaal Triangle Campus, 2015

Sin taxes have increased significantly during the past three years. There have been different opinions regarding the levying of sin taxes: in relation to whether it helps the government to raise revenue or reduces the consumption thereof. This study therefore investigates the actual purpose for these taxes by means of a literature and empirical review. An increase in sin taxes affects the poor more than the rich because such taxes are classified as a regressive type of tax. The primary research problem addressed by this literature study was to determine the percentage that the lower income earning group of South African citizens, who are funded by social grants, spend on sin taxed items. This study focused on two areas: the social grant system in conjunction with the Consumer Price Index (“CPI”) and the levying of sin taxes in South Africa. Over the years, South Africa has experienced an increase in its levels of poverty. There are eight types of social grants in South Africa, to which the lower income earning South African citizens, who live below the poverty line, are entitled, depending on their circumstances. This study discusses only seven of the eight social grants, by considering the purpose of the social grant, criteria, means testing requirements and the monthly amount available. These grants include the child support grant, old age grant, disability grant, foster care grant, care dependency grant, grant-in-aid and war veteran grant. The CPI of South Africa is briefly addressed in this study, followed by the increases over the past three years. The escalations of the social grants and that of the CPI of South Africa have been compared in order to determine whether the government remains concerned for their lower income earning citizens most of whom live below the poverty line. For purposes of this study, sin taxes have been narrowed down to include only alcoholic beverages and cigarettes. This study determined the increases of sin taxes on these substances over the past three years as well as the consumption thereof. Their consumption was determined by the sales volume. A comparison of the increases and consumption was made, the purpose of which was to determine government’s motivation for these increases. The empirical review of this study investigated the social grant recipients’ spending habits on these items. This was done by means of a self- developed questionnaire. The purpose of the questionnaire was to determine the percentage of their grant money that the social grant recipients spend on alcoholic beverages and cigarettes. The results and findings led to a conclusion which addressed the problem of this study. This study makes recommendations for further investigation of the sin tax implications for the lower income earning South African citizens, who are funded by social grants. / MCom (Accountancy)--North-West University, Vaal Triangle Campus, 2015

Thesis (MBA)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The global RTD market was one of the fastest growing drinks categories in the world in 2002 and many brewers and spirits companies have entered the new market. The RTD category gained most of their volume from the young adult consumers and across the boundaries of wine. spirits and beer. The strategic vision of the RID market determine whether this is a short intense fashion or a permanent feature in the drinks market, given the historical precedence of the mid to late 1980's when the wine cooler boom and later the alcopops (alcoholic carbonates) phenomenon passed as quickly as it came. The purpose of the research report sets out to investigate the global RTD markets in order to determine the strategic vision for the South African market. The study did a review of the top tcn RID markets and then focussed on the strategies and performance of the Australian and United Kingdom markets, due to the level of development and similarities in culture of these markets with the South African market. The analysis of the global RID markets showed the three successful RTD models are female, androgynous and male RIDs and consumers perceived and use the three types of RTDs differently. Amongst the most important suggestions the author recommends that the biggest opportunity for the South African R TD category is to gain market share from the beer market in the male sector, which is by far the biggest seller of alcoholic beverages in South Africa. The current successes in the South African market came from female and androgynous brands, but it is very difficult to maintain brand loyalty within these segments due to the nature of the young adult consumers and female drinkers. / AFRIKAANSE OPSOMMING: Die wereld gereed·om-te-drink (RTD) mark was een van die vinnigste groeiende drank kategoriee in die wereld in 2002 en baie brouerye en spiritualieë maatskappye het tot die nuwe mark toegetree. Die RTD kategorie het die meeste van sy volume verkry van die jong volwasse verbruikers en van verskillende kategoriee soos wyn, spiritualieë en bier. Die strategiese visie van die RTD mark bepaal of dit 'n gier of 'n permanente kenmerk in die drank mark is, soos voorafgegaan van die middel tot laat 19805 toe die wyn verfrissers en later die "alcopops" (alkoholiese karbonate) verskynsel so vinnig verdwyn het as wat dit gekom het. Die doel van die navorsingsverslag is om die wereld RTD mark te ondersoek om 'n strategiese visie vir die Suid-Afrikaanse mark te bepaal. Die navorsingstudie het die top tien RTD markte ondersoek en toe gefokus op die strategiee en doeltreffendheid van die Australiese en Verenigde Koninkrykte markte as gevolg van die vlak van ontwikkeling en ooreenkomste in kulture van die markte met die Suid-Afrikaanse mark. Die analise van die wereld RTD mark het getoon dat die drie suksesvolle vorme van RTDs is vroue, tweeslagtige en mans RTDs en dat verbruikers verstaan en gebruik die drie tipes van RTDs verskillend. Van die belangrikste voorstelle wat die skrywer maak is dat die grootste geleendheid vir die Suid-Afrikaanse RTDs is om mark aandeel van die bier kategorie in die mans sektor te verkry omdat dit die grootste alkohol kategorie in Suid-Afrika is. Die huidige sukses in die Suid-Afrikaanse mark het gekom van die vroue en tweeslagtige markte, maar dit is baie moeilik om die verbruikers lojaal te hou vir die RTD produkte in die segmente as gevolg van die aard van die jong volwasse verbruikers en vroue drinkers.

Thesis (MSc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Monoterpene alcohols (monoterpenols) play an important role in the flavour and aroma of grapes and wine. This is especially applicable to wines of a muscat variety, but these flavour compounds are also present in other non-muscat grape varieties, where they supplement other varietal flavours and aromas. These monoterpenols can be found in grapes and wine as free, volatile and odorous molecules, as well as in flavourless, nonvolatile glycosidic complexes. These complexes most often occur as 6-0-a-L-arabinofuranosyl-p-D-glucopyranosides (vicianosides), 6-0-P-D-xylopyranosyl- P-D-gluco-pyranosides (primverosides), 6-0-P-D-glucopyranosyl-p-D-glucopyranosides (gentio-biosides ), 6-0-a-L -rhamnopyra nosyl-p-D-g lucopyra nos ides (rutinos ides), or 6-0-p-D-apiofuranosyl-p-D-glucopyranosides of mainly linalool, geraniol, nerol, a-terpineol and hotrienol. These precursors are, however, hydrolyzed only to a limited extent by endogenous glycosidases during the fermentation process, as they exhibit very low activity in wine conditions. The monoterpenols can be released from their sugar moieties by one of two methods: either an acid or an enzymatic hydrolysis. The enzymatic hydrolysis mechanism is fully understood, and the process functions in two successive steps: firstly, depending on the precursor, the glycosidic linkage is cleaved by an a-L-arabinofuranosidase, an a-L-rhamnosidase, a p-D-xylosidase, or a p-D-apiosidase. The second step involves the liberation of the monoterpene alcohol by a p-glucosidase. This enzymatic hydrolysis does not influence the intrinsic aromatic characteristics of the wine, as opposed to acid hydrolysis. As the endogenous grape glycosides of Vitis vinifera and the yeast Saccharomyces cerevisiae show very low activity towards these aromatic precursors during the handling of the juice and winemaking processes, the focus has increasingly fallen on introducing exogenous p-glucosidases to wines and juices. Genes encoding p-glucosidases and a-L-arabinofuranosidases have been cloned from various organisms, including bacteria, fungi and yeasts. However, the activities and properties of these enzymes are not always suitable for exploitation under winemaking conditions, where a low pH, low temperatures, and high ethanol and glucose concentrations prevail. A genetically engineered wine yeast strain of S. cerevisiae that expresses glycosidases that are active in these conditions would be useful in improving the flavour and aroma of wines, thereby adding to the complexity and value of the wine. Two p-glucosidase genes, BGL 1 and BGL2 from Saccharomycopsis fibufigera, were subcloned into two Escherichia coli-yeast shuttle vectors. A dominant selectable marker gene (SMR1) was also inserted onto these plasmids. These plasmids were designated pBGL 1 (containing the BGL 1 gene) and pBGL2 (containing the BGL2 gene) respectively. Introduction of the two plasmids into two strains of S. cerevisiae then followed. A laboratory strain, L1278, was transformed to confirm the effective secretion of the expressed protein. An industrial yeast strain, VIN13, was subsequently transformed by making use of the selectable marker (resistance against sulfometuron). Enzyme assays with the synthetic substrate p-nitrophenol-j3-D-glucopyranoside (pNPG) were performed to determine the activity of the j3-glucosidases over a period of days, as well as at certain temperatures and pH values. The stability of the enzymes was also investigated. These recombinant yeasts were able to degrade the pNPG efficiently. They showed promising results concerning pH optima, with a substantial amount of activity found at the pH levels as found in the wine environment. There was also a slight increase in specific activity at lower temperatures. The recombinant yeast strains were also tested in smallscale fermentations. Three wines were made, of which two were from white cultivars (Chenin blanc and GewOrtztraminer) and one from red (Pinotage). Results obtained from micro-extraction from the finished wines showed that the terpenol content did increase, although this was not the only wine component influenced. Other flavour compounds also showed increases, especially the esters. This also played a role in the flavour increase in the wine. Future work would include optimizing the available results. This would entail the addition of another glycosidic enzyme, such as a-L-arabinofuranosidase, to the genome of the wine yeast to aid the further breakdown of glycosidic bonds. The cloning or engineering of a j3-glucosidase enzyme that is more active at low temperatures would also yield better results and release even more of the aroma of the wine. / AFRIKAANSE OPSOMMING: Monoterpeenalkohole (monoterpenole) speel 'n belangrike rol in die geur en aroma van druiwe en wyn. Dit is veral van toepassing op wyne van Muskaat-varieteite, maar hierdie geurkomponente is ook teenwoordig in ander nie-Muskaat druifsoorte, waar dit bydra tot die varieteitsqeur en aroma. Hierdie monoterpenole kom voor in druiwe as vry, vlugtige en aromatiese molekules, of as geurlose, nie-vlugtige glikosidies-gebonde komplekse. Hierdie komplekse is meestal in die vorm van 6-0-a-L-arabinofuranosiel-~-D-glukopiranosiede, 6- O-~-D-xilopiranosiel-~-D-glukopiranosiede (primverosiede), 6-0-~-D-glukopiranosiel-~-Dglukopiranosiede (gentiobiosiede), 6-0-a-L-ramno-pyranosiel-~-D-glukopiranosiede (rutinosiede), of 6-0-~-D-apiofuranosiel-~-D-glukopirano-siede van hoofsaaklik linalool, geraniol, nerol, a-terpineol en hotrienol. Hierdie geurvoorlopers word egter slegs tot In beperkte mate tydens die proses van fermentasie deur die endogene glikosidase ensieme gehidroliseer, aangesien hulle baie min aktiwiteit toon onder wynbereidingstoestande. Die monoterpenole kan op een van twee wyses van hul suikermolekules vrygestel word: 'n suurhidrolise, of ensiematiese hidrolise. Die ensiematiese hidroliseproses word baie goed begryp en behels twee opeenvolgende stappe: eerstens, afhangende van die aard van die voorloper, word die glikosidiese verbinding deur In a-L-arabinofuranosidase, In a-L-ramnosidase, In ~-D-xilosidase, of 'n ~-D-apiosidase gebreek. In die tweede stap word die monoterpeenalkohol deur In ~-glukosidase vrygestel. Hierdie ensiematiese afbraakproses verander nie die intrinsieke aromatiese kenmerke van die wyn, soos wat met suurhidrolise die geval is nie. Omdat die endogene glikosidases van Vitis vinifera en die van die gis Saccharomyces cerevisiae baie lae aktiwiteit ten opsigte van die aromatiese voorlopers gedurende die hantering van die druiwesap en wynmaakprosesse toon, val die fokus al hoe meer op die inkorporering van eksogene ~-glukosidases in wyn en sappe. Gene wat vir ~- glukosidases en a-L-arabinofuranosidases kodeer, is al vanuit verskeie organismes gekloneer, insluitende bakteriee, fungi en giste. Die aktiwiteite en kenmerke van hierdie ensieme is egter nie altyd wenslik vir hul gebruik in wyn nie, aangesien dit In omgewing is met 'n lae pH, lae temperatuur, en hoe etanolvlakke en glukose-konsentrasies. In geneties veranderde wyngis van S. cerevisiae wat in staat is om glikosidases uit te druk wat onder hierdie kondisies aktief is, sal baie handig te pas kom in die verbetering van die geur en aroma van wyne, om daardeur die kompleksiteit en die waarde van die wyn te verhoog. Twee ~-glukosidasegene, BGL 1 en BGL2 vanaf die gis Saccharomycopsis fibuligera , is in twee afsonderlike Esccherichia coli-gis-pendelplasmiede gesubkloneer. In Dominante selekteerbare merkergeen (SMR1) is ook in hierdie plasmiede gekloneer. Hierdie plasmiede word onderskeidelik pBGL 1 (met die BGL 1-geen) en pBGL2 (bevattende die BGL2-geen) genoem. Hierdie twee plasmiede is hierna apart na twee rasse van S. cerevisiae getransformeer. Eerstens is 'n laboratoriumras, L1278, getransformeer om te bevestig dat effektiewe sekresie en uitdrukking van die proteTen plaasvind. Hierna is 'n industriele gisras, VIN13, getransformeer deur gebruik te maak van die selektiewe merker (bestandheid teen sulfometuron). Ensiem-bepalings met behulp van die sintetiese substraat p-nitrofeniel-p-O-glukopiranosied (pNPG) is gedoen om die aktiwiteit van die p-glukosidqses oor 'n aantal dae te bepaal, asook om die aktiwiteit by sekere temperature en pH-vlakke te meet. Die stabiliteit van die ensieme is ook bepaal. Hierdie rekombinante giste was in staat om pNPG effektief af te breek. Hulle het belowende resultate betreffende die pH-optima getoon, met 'n aansienlike hoeveelheid aktiwiteit by die pH-vlakke soos dit in die wynomgewing voorkom. Daar was ook 'n effense verhoging in die ensieme se aktiwiteite by laer temperature. Die rekombinante gisrasse is ook in kleinskaalse wynfermentasies gebruik. Drie verskillende wyne is gemaak, waarvan twee wit kultivars was (Chenin blanc en GewOrtztraminer) en een 'n rooi kultivar (Pinotage). Resultate wat deur die mikro-ekstraksie van die voltooide wyne verkry is, het getoon dat die terpenolinhoud wei verhoog het, alhoewel dit nie die enigste wynkomponente was wat beinvloed is nie. Ander geurkomponente het ook 'n verhoging in konsentrasie getoon, veral die esters. Hierdie verbindings het ook 'n rol in die verhoging van geur in die wyne gespeel. Toekomstige werk sal die beskikbare resultate verder optimaliseer. Dit sal insluit die byvoeging van nog 'n glikosidiese ensiem, soos a.-L-arabinofuranosidase, tot die genoom van die wyngis, om verdere afbraak van glikosidiese verbindings teweeg te bring. Die klonering of verandering van 'n p-glukosidase-ensiem met verhoogde aktiwiteit by laer temperature sal ook beter resultate toon en meer geur in die wyn kan vrystel.

Dissertation (PhD)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Brandy production is a multi-step process that involves grape harvesting, base wine fermentation, distillation, wood maturation and blending. Within each of these production process steps there are a number of factors that can influence the composition and resultant quality of the base wine, unaged and wood matured distillates. These factors include geographic and climatic features of the origin of grapes used, viticultural practices, grape maturity, grape variety, vintage variation, vinification techniques, storage of the base wine prior to distillation, distillation technique, age and origin of oak wood used for maturation and barrel toasting levels. The composition of flavour is extremely complex in wine and distilled beverages such as brandy. A multitude of compounds can take part in the formation of flavour, and it is rare that a particular compound, that is solely responsible for nuances of a specific flavour, is identified. Thus, taking brandy production factors and the nature of aroma and flavour into account, it is clear that thorough understanding of the complexities affecting the perception of quality in brandy is difficult. In commercial brandy production, standard operating procedures do not allow for the separate distillation of brandy base wines from different producers and mixing of base wines from different regions and producers thus occurs. This makes it difficult to determine whether the quality determination of the base wine is in fact an indication of the quality of the resultant distillate after the required period of wood maturation. Therefore, the aim of this study is to determine whether there is any merit in storing and distilling brandy base wines from different producers and regions separately. This was done by firstly determining the demographic and production factors that influence brandy base wine composition. Secondly, the influence of brandy base wine composition on the quality of the respective unaged potstill distillates as well as the ultimate style and quality of the threeyear old wood matured potstill distillates was determined. For this purpose, four potstills with a capacity of 2000 L each were isolated and used for commercial scale distillations of 33 and 25 brandy base wines in 1999 and 2000, respectively, at the DisteIl distillery in Worcester. The experimental outlay used in the study closely emulated Distell's standard operating procedures for commercial brandy production. Chenin blanc and Colombar are the two most popular grape varietals used in the making of brandy base wine in South Africa. Due to the complexity of the brandy production process, the first part of the study only focussed on South African young Chenin blanc wines, with a predominantly fermentation derived aroma. The concentration of iso-amyl acetate, hexyl acetate, ethyl caprylate, ethyl caprate, 2-phenethyl acetate and octanoic acid was significantly higher in wines awarded gold and silver medals and decreased significantly with subsequent decreases in quality categories. Ethyl lactate exhibited the opposite pattern. A quality predictor model based on the behaviour of 21 volatile compounds quantified in these wines had a resonable prediction accuracy when having to predict the quality of wines made in the same vintages as it had been trained on. It was significantly poorer when tested on a completely different vintage of wines to the ones it had been trained on. The number of vintages, number of wines per vintage and the number of compounds quantified for the model influence its prediction accuracy. Twenty-seven volatile compounds were quantified in 33 and 25 brandy base wines, their unaged and three year old distillates from 1999 and 2000, respectively. ANOVA and CART analysis showed that vintage, region, harvest time, choice of cultivar and yeast strain can have a significant influence on the volatile compound composition of brandy base wines, their unaged and three year old distillates. These factors as well as the volatile compound composition were also found to influence the sensory quality of these products. Base wines, unaged and three year old distillates originating from the De Dooms region, which predominantly cultivates table grapes, were of significantly lower quality than those from the remaining regions. Products made from grapes harvested early in the season were of significantly higher quality. The volatile aroma compound composition was found to differ significantly between the 1999 and 2000 base wines and distillates, irrespective of the exclusion of those samples that had undergone partial or complete malolactic fermentation. Consequently, quality indicating compounds may vary from vintage to vintage. The relationship between the quality of brandy base wines and the concentration of n-butanol, iso-amyl acetate, ethyl lactate, ethyl caprylate, octanoic- and decanoic acid was the same as that reported in young Chen in blanc wines in this study. In unaged distillates, increased levels of ethyl lactate also exert a negative influence on distillate quality. Iso-amyl acetate, hexyl acetate, ethyl caproate, ethyl caprylate, n-butanol, octanoic acid, ethyl caprate and decanoic acid showed some positive correlation, whilst iso-butanol, ethyl lactate, acetic acid, acetaldehyde and ethyl acetate showed a significant negative correlation to three-year old distillate quality. Sensory descriptive analysis on selected good, average and poor quality distillates using the South African brandy aroma wheel showed that there are small differences in profile between the good and average distillates, there were however significant differences between the good and poor quality distillate profiles throughout maturation. After three years of wood maturation, the aroma profile of poor quality distillates can be characterised by prominent herbaceous and woody aromas, which are more intense than the fruity aromas. Good quality distillates contained characteristically intense fruity aromas. Volatile compound concentration differences were noted during the course of and after three years of wood maturation and in barrels of varying ages. Distillates matured in new block barrels exhibited significant differences in volatile and wood compound composition after three years when compared to remaining barrels used. The style classification of the three-year old potstill distillate was influenced by demographic and production factors and volatile compound composition, but not by the sensory quality of the distillates. In summary, vintage, region, cultivar, harvest time and choice of yeast strain have a significant influence on the volatile composition of brandy base wines, their unaged and three year old potstill distillates, which in turn affects the sensory quality of these products. These effects cannot be viewed in isolation as they jointly exert an influence on the composition and quality of these products. From a commercial perspective, this study has provided a valuable indication as to which production and demographic factors can influence the quality and style of potstill brandy. Thus, future brandy base wine intake should, as far as possible, take place in such a manner to allow base wines originating from the same cultivar or region or harvest time or combination thereof (and to a lesser extent yeast strain) to be received simultaneously at the distillery for distillation. / AFRIKAANSE OPSOMMING: Brandewyn produksie is 'n veelvoudige proses wat die volgende insluit: pars van druiwe, basiswyn fermentasie, verstoking, houtveroudering en versnyding. Binne hierdie stappe is verskeie faktore wat 'n invloed op die samestelling en resultate van die basiswyn, onverouderde en verouderde distillaat kan hê. Hierdie faktore sluit die volgende in: geografiese ligging, klimaat toestande van die streek van herkoms, wingerdboupraktyke, graad van rypheid, druifvarieteit, wynoes variasie, wynbou tegnieke, opberging van basiswyn voor distillasie, distillasie tegnieke, ouderdom en oorsprong van akkerhout vir die veroudering, asook tot watter mate die vat gerooster is. Die samestelling van geur in wyn en gedistilleerde produkte soos brandewyn is uiters kompleks. 'n Menigte samestellings kan deel vorm van die inhoud van die geur, en dit is raar dat 'n bepaalde verbinding alleenlik verantwoordelik is vir 'n kenmerkende geur. Weens die verskeidenheid van produksie faktore, aroma en smaak is volledige kennis van brandewyn ingewikkeld en kompliseerd om te verstaan. In kommersiële brandewynproduksie, maak standaard werksprosedures nie voorsiening vir aparte distillasie van basiswyn van verskillende produsente nie, en die vermenging van basiswyn van verskillende streke en produsente kom voor. Dit maak dit moeilik om te bepaal of die kwaliteit van die basiswyn of die distillaat na die neergelegde periode van houtveroudering, in werklikheid 'n beslissende indikasie op die kwaliteit van die verouderde produk is. Daarom is een van die doele van hierdie studie om te bepaal of daar meriete in is om brandewyn basiswyn van die verskillende produsente en streke apart te berg en te verstook. Dit is gedoen deur eerstens, die effek van demografiese en produksie faktore op die samestelling van brandewyn basiswyn te bepaal. Daarna, om die invloed van brandewyn basiswynsamestelling op die kwaliteit van onderskeidelik die onverouderde distillate sowel as die uiteindelike styl en kwaliteit van die 3 jaar oue houtverouderde potketel distillate, te bepaal. Vir hierdie doel, is vier potketels met 'n kapasiteit van 2000 liters elk geïsoleer en vir kommersiële skaal distillasies van 33 en 25 brandewyn basiswyne in 1999 en 2000, ondeskeidelik, by DisteIl Distillerdery, Worcester verstook. Die eksperimentele uitleg wat in hierdie studie gebruik is, ewenaar DisteIl se standaard verstokingsprosedures vir kommersiële brandewynproduksie. Chenin blanc en Colombar is die twee mees populêre druifvarieteite vir die maak van brandewyn basiswyn in Suid-Afrika. As gevolg van die kompleksiteit van die brandewyn produksieproses, is die eerste gedeelte van die studie gefokus op die Suid-Afrikaanse jong Chenin blanc wyne, met 'n oorheersende fermentasie geur. Die konsentrasie van iso-amyl asetaat, heksiel asetaat, etiel kaprilaat, etiel kapraat, 2-phenetiel asetaat en oktanoë suur was aansienlik hoër in wyne wat met goud en silwer medaljes bekroon is en neem aansienlik af met afname in kwaliteit kategorieë. Etiel laktaat vertoon die teenoorgestelde patroon. 'n Kwaliteit voorspellersmodel, gebaseer op die gedrag van 21 vlugtige komponente was opgestel. Die model het redelike akkuraatheid getoon op wyne van dieselfde oesjaar as waarop oorspronklik opgelei. Die model se voorspellingsakkuraatheid was aansienlik swakker toe dit vergelyk getoets is met wyne van 'n nuwe oesjaar. Die hoeveelheid oesjare, hoeveelheid wyne per oesjaar en die hoeveelheid verbindings gebruik in hierdie model sal die voorspellingsakkuraatheid beïnvloed. Sewe-en-twintig vlugtige komponente was gekwantifiseer in 33 en 25 brandewyn basiswyne, die onverouderde en 3 jaar oue distillate vanaf 1999 en 2000, onderskeidelik. Variasie ontledings (ANOVA) en klassifikasie en regressie ontledings (CART) ontledings wys dat oesjaar, streek, parstyd, keuse van kultivar en gisrasse In aansienlike invloed op die vlugtige samestelling van brandewyn basiswyne asook hul onverouderde en 3 jaar distillate het. Hierdie faktore, sowel as die vlugtige verbinding samestellings, beinvloed ook bevind die sensoriese kwaliteit van hierdie produkte. Basiswyne, onverouderde en 3 jaar oue distillate wat vanuit die De Doorns streek, wat hoofsaaklik tafeldruif kultivars is, is van In swakker kwaliteit as die ander streke. Produkte wat gemaak is van druiwe wat vroeg in die seisoen gepars is, was van beter kwaliteit. Die vlugtige geurkomponentsamestellings het tussen die basiswyne en distillate van die 1999 en 2000 oesjare verskil, ongeag of party van die monsters gedeeltelike of volledige appelmelksuurgisting ondergaan het. Gevolglik, die konsentrasie van kwaliteitaanwysende komponente mag van seisoen tot seisoen verskil. Die verhouding tussen die kwaliteit van die brandewyn basiswyne en die konsentrasie van n-butanol, iso-amiel asetaat, etiel laktaat, etiel kaprilaat, oktanoë- en dekanoë suur was dieselfde soos gerapporteer oor die jong Chenin blanc wyne. In onverouderde distillate, het verhoogde vlakke van etiel laktaat In negatiewe invloed op distillaat kwaliteit veroorsaak. Iso-amiel asetaat, heksiel asetaat, etiel kaproaat, etiel kaprilaat, n-butanol, oktanoë suur, etiel kapraat en dekanoë suur In positiewe korrelasie, terwyl iso-butanol, etiel laktaat, asynsuur, asetaldehied en etiel asetaat betekenisvolle negatiewe korrelasie met 3jaar oue distillaat kwaliteit bewys. Beskrywende sensoriewe analises op geselekteerde, middelmatige en swak kwaliteit distillate (gedoen deur gebruik making van die Suid-Afrikaanse Brandewyn Aromawiel) wys dat daar klein verskille tussen die profiele van goeie en middelmatige distillate is. Daar is egter aansienlike verskille tussen goeie en swak kwaliteit distillataat profiele regdeur die drie jaar verouderingsperiode. Na 3 jaar van houtveroudering kan die geur profiel van swak kwaliteit distillate uitgeken word aan kruid- en houtagtige geure, wat meer intens as die vrugagtige geure is. Goeie kwaliteit distillate het intense vrugagtige-aroma eienskappe. Vlugtige verbinding konsentrasie verskille is waargeneem gedurende en na die 3jaar houtverouderingsperiode in vate wat van ouderdomme verskil. Distillate wat in nuwe blokkies vate verouder is, vertoon aansienlike verskille in vlugtige en houtkomponent samestellings na 3 jaar wanneer dit met die, wat in die oorblywende ouer vate verouder is, vergelyk word. Die styl klassifikasie van die 3 jaar oue potketeldistillaat was deur demografiese en produksie faktore sowel as vlugtige verbinding samestellings beïnvloed, maar nie met die sensoriese kwaliteit van die distillate nie. In opsomming, oesjaar, streek, kultivar, parstyd en keuse van gisrasse het 'n aansienlike invloed op die vlugtige komponent samestelling van die brandewyn basiswyne, onverouderde en 3 jaar oue potketel distillate, wat weer op hul beurt die sensoriese kwaliteit van die onderskeidelike produkte beïnvloed. Die effek van hierdie faktore kan nie in isolasie gemeet word nie, aangesien dit gesamentlik die kwaliteit van die produkte beïnvloed. Van 'n kommersiële perspektief het hierdie studie 'n waardevolle indikasie gelewer van hoe produksie en demografiese faktore die kwaliteit en styl van potketelbrandewyn kan beïnvloed. Daarom word voorgestel dat toekomstige brandewyn basiswyn innames, sover as moontlik, voorsiening moet maak om wyne van dieselfde kultivar, uit dieselfde streek, parsseisoen inaggeneem, of kombinasie daarvan, met 'n mindermate die gisrasse in aanmerking geneem, gelyktydig vir verstoking by die distilleerderye ontvang word sodat hierdie wyne apart van wyne met ander bogenoemde variasies verstook en verouder kan word.