Thesis (PhD (Wine Biotechnology))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Alcoholic fermentation, and especially wine fermentation, is one of the most ancient microbiological processes utilized by man. Yeast of the species Saccharomyces cerevisiae are usually responsible for most of the fermentative activity, and many data sets clearly demonstrate the important impact of this species on the quality and character of the final product. However, many aspects of the genetic and metabolic processes that take place during alcoholic fermentation remain poorly understood, including the metabolic processes that impact on aroma and flavour of the fermentation product. To contribute to our understanding of these processes, this study took two approaches: In a first part, the initial aim had been to compare two techniques of transcriptome analysis, DNA oligo-microarrays and Serial Analysis of Gene Expression (SAGE), for their suitability to assess wine fermentation gene expression changes, and in particular to assess their potential to, in combination, provide combined quantitative and qualitative data for mRNA levels. The SAGE methodology however failed to produce conclusive data, and only the results of the microarray data are shown in this dissertation. These results provide a comprehensive overview of the transcriptomic changes during model wine fermentation, and serve as a reference database for the following experiments and for future studies using different fermentation conditions or genetically modified yeast. In a second part of the study, a screen to identify genes that impact on the formation of various important volatile aroma compounds including esters, fatty acids and higher alcohols is presented. Indeed, while the metabolic network that leads to the formation of these compounds is reasonably well mapped, surprisingly little is known about specific enzymes involved in specific reactions, the genetic regulation of the network and the physiological roles of individual pathways within the network. Various factors that directly or indirectly affect and regulate the network have been proposed in the past, but little conclusive evidence has been provided. To gain a better understanding of the regulations and physiological role of this network, we took a functional genomics approach by screening a subset of the EUROSCARF strain deletion library, and in particular genes encoding decarboxylases, dehydrogenases and reductases. Thus, ten genes whose deletion impacted most significantly on the aroma production network and higher alcohol formation were selected. Over-expression and single and multiple deletions of the selected genes were used to genetically assess their contribution to aroma production and to the Ehrlich pathway. The results demonstrate the sensitivity of the pathway to cellular redox homeostasis, strongly suggest direct roles for Thi3p, Aad6p and Hom2p, and highlight the important role of Bat2p in controlling the flux through the pathway. / AFRIKAANSE OPSOMMING: Alkoholiese fermentasie, en veral die maak van wyn, is een van die vroegste mikrobiologiese prosesse wat deur die mensdom ingespan is. Die gisspesie Saccharomyces cerevisiae is gewoonlik grotendeels verantwoordelik vir die fermentasie and verskeie vorige studies het gedemonstreer dat hierdie spesie ‘n baie belangrike rol speel in die uiteindelike kwaliteit en karakter van die voltooide produk. Nieteenstaande die feit is daar steeds baie aspekte van beide die genetiese en metaboliese prosesse wat plaasvind tydens alkoholiese fermentatsie wat nog swak verstaan word, insluitende metaboliese padweë wat ‘n impak het op die smaak en aroma van die fermentasie produk. Om ons kennis van die veld uit te brei het die studie twee aanslae geneem: In die eerste geval is gepoog om twee tegnieke van transkriptoom analiese, nl. DNA oligomikro- arrays en Serial Analysis of Gene Expression (SAGE) te bestudeer vir hul vermoë om geen ekspressie veranderinge tydens wynfermentasie te ondersoek en meer spesifiek om hul potensiaal om ‘n kombinasie van kwantitatiewe sowel as kwalitatiewe data met betreking to mRNA vlakke te produseer. Die SAGE metode kon egter geen betroubare resultate produseer nie en dus word slegs die resultate van die mikro-array eksperimente in die tesis bespreek. Die resultaat is ‘n geheeloorsig oor die geenekspressie veranderinge wat so ‘n wyngis tydens alkoholiese fermentasie ondergaan en dien as ‘n verwysingsraamwerk vir toekomstige studies met geneties gemodifiseerde gis of selfs verskillende fermentasieparameters. Die tweede deel van die studie het gefokus op die identifikasie van gene wat ‘n impak het op die vorming van belangrike, vlugtige aroma komponente, o. a. Esters vetsure en hoër alkohole d.m.v. ‘n siftingseksperiment. Alhoewel daar redelik baie inligting is oor die onderligende metaboliese netwerke wat lei tot die vorming van die verbindings, is daar min kennis van die genetiese regulasie van die netwerk en die fisiologiese rol van individuele padweë wat die netwerk vorm. Verskeie faktore – wat of die netwerk direk of indirek affekteer – is al voorgestel, meer met min konkrete bewyse. Dus het ons gepoog om meer lig op die onderwerp te laat m.b.v. ‘n funksionele genoom aanslag deur ‘n siftingseksperiment te doen op ‘n subgroep (spesifiek gene wat kodeer vir dekarboksilase, dehidrogenase en reduktase ensieme) van die EUROSCARF delesiebiblioteek. Dus is tien gene geïdentifiseer – die delesie waarvan ‘n merkbare effek het op die aroma produksie netwerk en spesifiek die van hoër alkohole. Ooruitdrukkings en enkel en meervoudige delesie rasse van die tien gene is gemaak om d.mv. genetiese analiese, hulle rol in aroma produksie en die Ehrlich padweh uit te pluis. Die resultate toon dat hierdie padweg sensitief is teenoor die sellulêre redoks balans en dui op direkte rolle vir Thi3p, Aad6p en Hom2p, asook dat Bat2p ‘n baie belangrike rol speel in die werking van die padweg.

Thesis (MBA)--University of Stellenbosch, 2011. / Wine is not the alcoholic beverage of choice for the average South African. South Africa‟s wine consumption per capita is much lower than in other wine producing countries. It would be hugely beneficial to the South African wine industry if our domestic market were beter developed. This study aims to improve our understanding and knowledge of the South African wine market by exploring the purchasing behaviour and preferences of the South African wine consumer. This objective is attained by identifying whether a correlation exists between demographic variables and wine purchasing behaviour in the South African market. A literature review of international research indicated that various demographical, behavioural and other determinants significantly influence a consumer's decision to buy wine. This information was used to formulate a data collection strategy. A quota sampling strategy was used and the data was collected with the help of an online questionnaire. This study used the chi-squared test of a contingency table to determine if a relationship exists between any of the variables and the Cramer‟s V test was used to measure the strength of the association. This study produced similar results as other international studies conducted on the factors influencing wine purchasing behaviour. The male survey respondents tended to spend more on average on a bottle of wine and had on average a higher wine knowledge when compared to the female survey respondents. The older survey participants consumed more wine and tended to spend more per month on wine compared to their younger counterparts. The respondents in the higher income groups tended to spend more per month on wine and purchased wine that is more expensive when compared to their counterparts in the lower income groups. This study found significant relationships between wine knowledge and wine purchasing variables. Higher levels of wine knowledge often lead to higher wine consumption levels. Furthermore, the respondents in the higher wine expenditure groups generally possessed a higher wine knowledge compared to the respondents in the lower expenditure groups. This study found a number of significant relationships between the purchasing behaviour and the preferences of the survey respondents. The respondents in the higher consumption groups preferred red or white wine and had an adverse preference for wine in the “other” category. Furthermore, most red and sparkling wine consumers preferred a natural cork while most dry white wine consumers preferred a screwcap as closure method. The respondents displayed a possible willingness to pay more for a bottle of red wine than for a bottle of white wine. Furthermore, the respondents favoured screwcap in the lower average price category and preferred a natural cork in the higher average price categories. The survey participants tended to purchase wine at different price points and did not only buy wine in one price bracket.

Thesis (MScAgric) -- Stellenbosch University, 1944. / INLEIDING: Gedurende die afgelope twee dekades, terwyl die wereld die ekonomiese terugslag van die Eerste Wereld-Oorlog in sy volle felheid beleef het, het prysbeheer in verskeie lande meer en meer op die voorgrond getree. Die feit dat na prysbeheer so gretiglik gegryp word, selfs wanneer demokratiese lande in 'n ekonomiese wurggreep worstel, wys op die feit dat prysbeheer beskou ,is as 'n noodhulpmaatreel. Hoe ernstiger die ekonomiese nood, hoe meer algemeen is prysbeheer.

Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In recent years South African wines have been under the spotlight due to references in the international wine media to a distinctive ‘burnt rubber’ character. Many winemakers and wine experts argued that the peculiar character could be ascribed to winemaking errors linked to mismanaged fermentation. An alternative possible source of the taint was identified in the coal tar creosote used as a wood preservative in vineyard trellis systems. South African regulations allow for the use of creosoted utility poles in agricultural land, but in Europe and USA their usage has been highly regulated and even banned for certain applications. Contamination of foodstuff by polycyclic aromatic hydrocarbons (PAHs) is one of the major motives for the banning of creosote in Europe and USA. Some of the compounds in the creosote mixture display very strong odour characteristics and for this reason it became the focus of attention for the present study. The overall aim of this study was to determine if vines trellised with creosoted posts could accumulate or absorb the various malodorous compounds deriving from the wood treatment onto the grape berries. These compounds could then be extracted from the grape berries into the wine during alcoholic fermentation, creating quality and sensory problems. Chapter 2 of this thesis gives an overview of the extensive literature that deals with methods of analysis of PAHs and malodorous phenols using both Gas Chromatography (GC), as well as High Performance Liquid Chromatography (HPLC). New methods for sample preparation, as well as analysis of PAHs using HPLC-Diode Array Detector (DAD), were developed and the results reported in Chapter 3. It was demonstrated that Sauvignon blanc experimental wines contained only chrysene at very low levels. The concentrations of chrysene found in the experimental wines are within the prescribed parameters as established by The Commission of the European Communities. Since no other PAH compounds were found in the samples analysed, it was concluded that the experimental wines were safe for human consumption and complied with EU regulations. The effect of vineyard posts on the sensorial characteristics of wine is discussed in Chapter 4. Creosoted poles were found to be responsible for an off-flavour described as ‘burnt rubber’ and ‘tarry’ in Merlot wines produced from grapes grown in close proximity to the posts. Following some of the reported findings, new guidelines have been introduced in the Integrated Production of Wine certification, which advise against the use of creosoted poles for vineyard trellising. This preliminary but important guideline will bring the South African wine industry a step closer to the fulfilling the obligations for food safety as required by the legislation of our major export partners. Future investigations are recommended to completely understand and evaluate the cumulative effect of creosoted posts in a fully trellised vineyard. / AFRIKAANSE OPSOMMING: Oor die afgelope paar jaar is Suid-Afrikaanse wyne onder die soeklig geplaas as gevolg van verwysings in die internasionale wynmedia na ‘n duidelike ‘gebrande rubber’-karakter. Baie wynmakers en wyndeskundiges het aangedui dat hierdie besonderse karakter toegeskryf kan word aan wynbereidingsfoute wat verband hou met gisting wat wanbestuur is. ‘n Alternatiewe moontlike oorsprong van die smaak is geïdentifiseer in die koolteer wat as ‘n houtpreserveermiddel in wingerdopleistelsels gebruik word. Suid-Afrikaanse regulasies maak voorsiening vir die gebruik van kreosoteerde nutspale in landbougrond, hoewel hulle gebruik in Europa en die VSA hoogs gereguleerd en in sommige gevalle selfs verbied is. Die besmetting van kossoorte deur polisikliese aromatiese koolwaterstowwe (polycyclic aromatic hydrocarbons (PAHs)) is een van die vernaamste redes vir die verbanning van kreosoot in Europa en die VSA. Sommige van die verbindings in die kreosootmengsel het baie sterk geurkenmerke en daarom is dit die fokus van die huidige studie. Die oorhoofse doelwit van hierdie studie was om te bepaal of wingerde wat op kreosoteerde pale opgelei is, die verskillende onwelriekende verbindings afkomstig van die houtbehandeling in die druiwekorrels kan akkumuleer of absorbeer. Hierdie verbindings sou dan tydens alkoholiese gisting uit die druiwekorrels in die wyn geëkstraheer kon word, wat aanleiding sou gee tot kwaliteits- en sensoriese probleme. Hoofstuk 2 van hierdie tesis verskaf ‘n oorsig van die breedvoerige literatuur wat handel oor metodes om PAH’s en onwelriekende fenole met behulp van beide gaschromatografie (GC) en hoëdrukvloeistofchromatografie (HPLC) te analiseer. Nuwe metodes is ontwikkel om monsters voor te berei en om PAH’s met behulp van ‘n HPLC-diode array detector (DAD) te analiseer. Die resultate word in Hoofstuk 3 gerapporteer. Daar is aangetoon dat die eksperimentele Sauvignon blanc-wyne chriseen teen baie lae vlakke bevat het. Die konsentrasies van chriseen wat in die eksperimentele wyne gevind is, is binne die voorgeskrewe parameters van die Kommissie van die Europese Gemeenskap. Aangesien daar nie ander PAHverbindings in die geanaliseerde monsters gevind kon word nie, is daar tot die gevolgtrekking gekom dat die eksperimentele wyne veilig is vir menslike verbruik en aan die EG-regulasies voldoen. Die effek van wingerdpale op die sensoriese kenmerke van wyn word in Hoofstuk 4 bespreek. Kreosoteerde pale is gevind wat verantwoordelik is vir ‘n wangeur in Merlot-wyne afkomstig van druiwe wat naby die pale gegroei het en wat as ‘gebrande rubber’ en ‘teeragtig’ beskryf is. Op grond van sommige van die gerapporteerde bevindings, is nuwe riglyne ingesluit in die sertifisering vir die Geïntegreerde Produksie van Wyn, wat aanbeveel dat kreosoteerde pale nie vir wingerdoplei gebruik word nie. Hierdie voorlopige, maar belangrike riglyn sal die Suid-Afrikaanse wynbedryf al beter in staat stel om te voldoen aan die voedselveiligheid regulasies wat vereis word deur die wetgewing van ons belangrikste uitvoervennote. Toekomstige ondersoeke moet aangewend word om die kumulatiewe effek van kreosoteerde pale in volledig opgeleide wingerde ten volle te verstaan en te evalueer. / Indaba Scholarship and Winetech for their financial support

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The present study was initiated by the wine industry of South Africa to overcome the lack of available information on the flavor and aroma of South African wines. The aim was to develop new analytical methods and improve existing ones for the analysis of volatile compounds in the South African wines. Initially a new analytical method based on stir bar sorptive extraction (SBSE) in the headspace mode for the analysis of 37 pre-selected volatile compounds was developed and validated. Consequently, the method was improved by making important modifications and increasing the number of compounds analyzed to 39. This method was successfully applied to a large number of Pinotage wines of vintages 2005 and 2006. The quantitative data of these wines were subjected to chemometric analysis in order to investigate possible co- /variances. A clear distinction was observed between the two vintages, where the 2005 wines were more characterized by wood-related compounds and the 2006 wines by the fermentation compounds. The developed method was further applied to other cultivars of vintage 2005, including two white (Sauvignon Blanc and Chardonnay) and three red (Shiraz, Cabernet Sauvignon and Merlot) cultivars. In a similar fashion, the quantitative data of the six cultivars of vintage of 2005 were analysed by chemometric methods. Significant differences were observed between the two white cultivars and among the four red cultivars. It was shown that among these cultivars, the major role-players were the wood and fermentation related volatiles. A striking observation was the confirmation of the unique character of the Pinotage wines compared to the other red cultivars, mainly influenced by the high level of isoamyl acetate and low level of isoamyl alcohol, the former being categorized as a varietal compound for Pinotage expressed by a fruity (banana) odor. In addition, advanced chromatographic technology in the form of comprehensive twodimensional gas chromatography (GC × GC) coupled to time-of-flight mass spectrometry (TOFMS) was investigated for the detailed analysis of volatile compounds in young South African wines. This work focused primarily on Pinotage wines. In the first instance, solid phase micro extraction (SPME) in the headspace mode in combination with GC × GC-TOFMS was used. Due to the high resolution and large peak capacity of GC × GC, more than 200 compounds previously reported as wine components were identified. These compounds were dominated by the highly volatile and less polar compounds, mainly due to the characteristics of SPME. In an attempt to further extend these results, another selective extraction method, solid phase extraction (SPE) was used in combination with GC × GC-TOFMS analysis. Using this technique, more than 275 compounds, most of them unidentified using the previous method, were detected. These groups of compounds include volatile phenols, lactones as well as mostly aromatic esters and norisoprenoids, which can potentially influence the aroma and flavor of wine. The techniques developed as part of this study have extended our knowledge of the volatile composition of South African wines. / AFRIKAANSE OPSOMMING: Hierdie studie is geïnisieer deur die wyn industrie van Suid-Afrika om die tekort aan beskikbare inligting aangaande wyn aroma van Suid-Afrikaanse wyne te oorkom. Die doel was om nuwe analitiese metodes te ontwikkel en die huidige metodes te verbeter vir die analise van vlugtige verbindings in Suid-Afrikaanse wyne. Oorspronklik is ʼn nuwe analitiese metode ontwikkel en gevalideer gebaseer is op ‘stir bar sorptive extraction’ (SBSE) in die gas fase vir die analise van 37 vooraf geselekteerde vlugtige verbindings. Die metode is verbeter deur belangrike modifikasies aan te bring en die hoeveelheid verbindings wat analiseer word te vermeerder na 39. Hierdie metode is suksesvol aangewend op ʼn groot hoeveelheid Pinotage wyne van oesjare 2005 en 2006. Die kwantitatiewe data van hierdie wyne is onderwerp aan verskillende chemometriese analises om moontlike ko-/variasies te ondersoek. ʼn Duidelike onderskeid is opgemerk tussen die twee oesjare, waar die 2005 wyne gekarakteriseer is deur hout-verwante verbindings en die 2006 wyne weer meer deur fermentasie verbindings. Die verbeterde metode is verder aangewend vir analiese van ander kultivars van oesjare 2005, wat twee wit (Sauvignon Blanc en Chardonnay) en drie rooies (Shiraz, Cabernet Sauvignon en Merlot) ingesluit het. Die kwantitatiewe data van die ses kultivars van oesjaar 2005 is op ʼn soortgelyke wyse geanaliseer deur verskillende chemometriese metodes te gebruik. Beduidende verskille is opgemerk tussen die twee wit kultivars en tussen die vier rooi kultivars. Die hoof rolspelers tussen die ses kultivars was weereens die verbindings wat ʼn hout en fermentasie aard het. Die unieke karakter van die Pinotage wyne in vergelyking met die ander rooi kultivars was opvallend. Hierdie wyn word gekarakteriseer deur hoë vlakke van isoamiel asetaat en lae vlakke van isoamiel alkohol, waar eersgenoemde gekatogiseer word as ʼn verbinding wat ʼn vrugte (piesang) geur in Pinotage uitdruk. Verder is gevorderde chromatografiese tegnologie in die vorm van ‘comprehensive two-dimentional gas chromatography’ (GC x GC) gekoppel met ‘time-of-flight mass spectroscopy’ (TOFMS) ondersoek vir die analiese van vlugtige verbindings in jong Suid-Afrikaanse wyne. Hierdie werk het hoofsaaklik op Pinotage wyne gefokus. Eerstens is ‘solid phase micro extraction’ (SPME) in die gas fase gekombineer met GC x GC-TOFMS. As gevolg van die hoë resolusie en groot piek kapasiteit van GC x GC is meer as 200 verbindings wat voorheen gerapporteer is as wyn komponente geïdentifiseer. Hierdie verbindings is gedomineer deur hoë vlugtige polêre verbindings, hoofsaaklik as gevolg van die karaktersitieke van SPME..In ʼn poging om die metode verder te verbeter is ʼn selektiewe ekstraksie metode naamlik ‘solid phase extraction’ (SPE) in kombinasie met GC x GC-TOFMS gebruik. Met hierdie tegniek is meer as 275 verbindings geïdentifiseer, waarvan die meeste nie met die vorige metode waargeneem is nie. Hierdie verbindings sluit vlugtige fenole, laktone en meestal aromatiese esters en norisoprenoïdes in, wat moontlik die reuk en smaak van wyn kan beïnvloed. Die metodes ontwikkel gedurende die studie het nuwe informasie verskaf aangaande die vlugtige komponente teenwoordig in Suid Afrikaanse wyne.

Thesis (MSc Food Sc (Food Science))--University of Stellenbosch, 2010. / 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 combinations, and to further investigate their effect on consumer liking. Finally, this project aimed to investigate the incidence of these compounds in a small range of South African wines. The sensory detection thresholds of 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol, 4- vinylphenol, 4-vinylguaiacol, isovaleric acid, isobutyric acid and acetic acid were determined. Apart from 4-ethylcatechol, these values generally agreed well with recent literature where values determined in wine are available. However, the discrepancies highlighted the importance of the effect of the medium (wine) when determining sensory detection thresholds. The use of the median as alternative calculation method was also investigated, and it was found that this method gives more insightful results than the standard American Society of Testing Materials (ASTM E679-04) method. Four compounds, namely 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol and isovaleric acid were profiled individually in wine using a trained sensory panel. It was found that all four compounds caused a suppression of the natural berry-like character in the wine, which induced a sick-sweet character. 4-ethylphenol contributed Elastoplast™ and leather aromas in the wine, both of which are commonly associated with Brettanomyces taint. 4-ethylguaiacol added a medicinal aroma to the wine, and 4-ethylcatechol and isovaleric acid were responsible for savoury and pungent aromas, respectively. 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol and isovaleric acid were also profiled in combination according to the central composite design. Several univariate and multivariate methods were applied to the dataset obtained. PARAFAC, a multiway method not widely utilized regarding sensory data, was applied to the data, the results of which were complementary to those obtained during univariate and multivariate analyses. It was found that there is a great deal of interaction between the four compounds profiled in terms of sensory effects. The most notable was the Elastoplast™ attribute, the intensity of which was affected by all four compounds. The pungent attribute was also affected by the 4-ethylphenol concentration. Consumer analysis revealed that some of the samples spiked with Brettanomyces-spoilage compounds were preferred to the unspiked (control sample). However, no further relationship could be found between consumer liking and either chemical composition or sensory profile. It is therefore speculated that consumer liking of Brettanomyces infected wine is driven by more complex sensory or socio-demographic factors. Finally, the concentration of 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol, 4-vinylphenol, 4- vinylguaiacol, isovaleric acid, isobutyric acid and acetic acid was determined in a small set of South African wines, selected to contain a high proportion of wines spoiled by Brettanomyces. Significant correlations were found between 4-ethylphenol and 4-ethylguaiacol, as well as 4- ethylphenol and isovaleric acid. However, no correlation could be found between 4-ethylphenol and 4-ethylcatechol. It is speculated that this lack of relationship is due to the different precursor profiles present in the analysed wines. This study paved the way for future investigations on the sensory effects of Brettanomyces spoilage in Pinotage red wine. / AFRIKAANSE OPSOMMING: Hierdie studie het gefokus op die sensoriese invloed van die belangrikste vlugtige komponente wat deur die Brettanomyces gis geproduseer word en bederf veroorsaak in wyn. Eerstens is gefokus op die bepaling van die deteksiedrempelwaardes van agt Brett-verwante bederwende komponente. Die tweede doelwit was om die sensoriese invloed van vier van die mees belangrike Brett-komponente te bepaal wanneer hulle individueel in wyn voorkom. Die derde doelwit was om die sensoriese invloed van hierdie vier komponente te bepaal wanneer hulle in verskillende kombinasies in wyn voorkom, asook die effek daarvan op verbruikervoorkeur. Laastens is gepoog om die voorkoms van hierdie komponente in ‘n klein seleksie van Suid- Afrikaanse wyne te bepaal. Die sensoriese deteksiedrempelwaardes vir 4-etielfenol, 4-etielguaiacol, 4-etielcatechol, 4- vinielfenol, 4-vinielguaiacol, isovaleraatsuur, isobuteraatsuur en asynsuur is bepaal. Met die uitsondering van 4-etielcatechol het die waardes oor die algemeen goed ooreengestem met waardes wat onlangs in die wetenskaplike literatuur gepubliseer is. Die uitsonderings het egter die belangrikheid van die medium (wyn) gedurende die bepaling van sensoriese deteksiedrempelwaardes uitgelig. Die gebruik van die mediaan as ‘n alternatiewe berekeningsmetode is ook ondersoek en daar is gevind dat hierdie metode meer insiggewende resultate lewer as die standaard American Society of Testing Materials (ASTM E679-04) metode. Vier komponente naamlik 4-etielfenol, 4-etielguaiacol, 4-etielcatechol en isovaleraatsuur is individueel in wyn geprofileer met behulp van ‘n opgeleide sensoriese paneel. Daar is gevind dat al vier die komponente die natuurlike bessiekarakter in die wyn onderdruk terwyl dit aanleiding gee tot ‘n onnatuurlike soet karakter. 4-etielfenol is gekenmerk aan Elastoplast™ en leeragtige aromas in die wyn en beide van hulle word algemeen geassosieer met Brettanomyces bederf. 4-etielguaiacol het ‘n medisinale aroma tot die wyn toegevoeg en 4- etielcatechol en isovaleraatsuur het respektiewelik souterige (“savoury”) en sterk (“pungent”) aromas tot gevolg gehad. 4-etielfenol, 4-etielguaiacol, 4-etielcatechol en isovaleraatsuur is ook in verskeie kombinasies geprofileer volgens die sentrale saamgestelde ontwerp (“central composite design”). Verskeie enkelveranderlike en meerveranderlike statistiese analisemetodes is ook op die datastel uitgevoer. PARAFAC, ‘n meerrigtingsmetode wat nie normaalweg vir sensoriese analise data gebruik word nie, is ook uitgevoer op die data en die resultate was komplimentêr tot die van die enkelveranderlike en meerveranderlike analisemetodes. Daar is gevind dat, met betrekking tot sensoriese effekte, daar noemenswaardige interaksie tussen die vier komponente plaasvind. Die mees opmerklike hiervan was die Elastoplast™ aroma, waarvan die intensiteit deur al vier die ander komponente geaffekteer is. Verder is die sterk (“pungent”) aroma beïnvloed deur die 4-etielfenol konsentrasie. Verbruikersvoorkeur-analise het aangedui dat sommige van die monsters waarby Brettanomyces bederwende komponente gevoeg is, verkies word bó die kontrole-wyn. Daar kon egter geen verdere verband gevind word tussen die verbruiker se voorkeur en, nog die chemise komposisie of sensoriese profiele, van die wyn nie. Daar kan dus gespekuleer word dat verbruiker voorkeur van Brettanomyces bederfde wyn gedryf word deur meer komplekse en sosio-demografiese faktore. Laastens is die konsentrasies van 4-etielfenol, 4-etielguaiacol, 4-etielcatechol, 4-vinielfenol, 4- vinielguaiacol, isovaleraatsuur, isobuteraatsuur en asynsuur in ‘n seleksie van Suid-Afrikaanse wyne bepaal. Dié wyne is spesifiek so gekies sodat ‘n aansienlike aantal van hulle met Brettanomyces bederf was. Betekenisvolle korrelasies is gevind tussen 4-etielfenol and 4- etielguaiacol, sowel as 4-etielfenol en isovaleraatsuur. Daar is egter geen korrelasie tussen 4- etielfenol and 4-etielcatechol gevind nie. Daar word vermoed dat hierdie gebrek aan korrelasie te wyte is aan die voorloperkomponent profiele teenwoordig in die wyne. Hierdie studie het die weg gebaan vir verdere ondersoeke na die sensoriese effekte van Brettanomyces bederf in Pinotage rooi wyn.

Wine grape pomace (WGP), the byproduct from winemaking, is a good source of polyphenols and dietary fibers, and may be utilized as antioxidant dietary fibers (ADF) for food applications. The objectives of this thesis research were to first determine the phenolic compounds, antioxidant and antimicrobial activities in red WGP under different drying processes for long-term storage, and to further evaluate the feasibility of using WGP as a functional food ingredient in yogurt and salad dressing for enhancing the nutritional value and improving storability of the products. Two types of WGP samples, pomace containing seeds and skins (P) and pomace with skins only (S) from Pinot Noir (PN) and Merlot (M) were studied. Samples were subjected to four different drying conditions: 40 °C conventional and vacuum oven, 25 °C ambient air and freeze dry. Total phenolic content (TPC, by Folin-Ciocalteu assay), anthocyanins (ACY, by pH differential method) and flavanols content (TFC, by vanillin assay) of the samples along with their antioxidant activity (DPPH radical scavenge method, RSA) and antibacterial activity (minimum inhibition concentration, MIC) were determined during 16 weeks of storage under vacuum condition at 15±2 °C. Meanwhile, dietary fiber profile was evaluated by using gravimetric-enzyme method. Results showed that dietary fiber contents of PN-P, PN-S, M-P and M-S were 57-63% d.m. with the majority of insoluble fraction. Freeze dried WGP retained the highest bioactive compounds with TPC 21.19-67.74 mg GAE/g d.m., ACY of 0.35-0.76 mg Mal-3-glu/g d.m., TFC of 30.16-106.61 mg CE/g d.m. and RSA of 22.01-37.46 mg AAE/g d.m., followed with ambient air dried samples. Overall, TPC, TFC and RSA were higher in PN than in M, and higher in pomace than in skins, while reverse results were observed in ACY. All samples lost significant amount of bioactive compounds during storage, in which ambient air and freeze dried samples had TPC reduction of 32-56% and 35-58%, respectively at the end of 16 weeks of storage. RSA in PN-P and M-P remained more than 50 mg TE/g d.m., meaning WGP still met the criteria of ADF definition after 16 weeks of storage. WGP extracts showed higher antibacterial efficiency against L. innocua than that of E. coli with MIC of 2, 7, 3 and 8% against L. innocua, and 3, 6, 4 and 9% against E. coli for PN-P, PN-S, M-P and M-S samples, respectively. This study demonstrated that Pinot Noir and Merlot pomace are good sources of ADF even after 16 weeks of storage at 15 °C and vacuum condition. Due to the highest antioxidant activity (RSA 37.46 mg AAE/g) and dietary fiber content (61%), PN-P was selected as ADF to be fortified in yogurt and salad dressing. Three types of WGP: whole powder (WP), liquid extract (LE) and freeze dried extract (FDE) with different concentrations were incorporated into yogurt (Y), Italian (I) and Thousand Island (T) salad dressings. TPC, RSA and dietary fiber content, major quality attributes including pH and peroxide value (PV) during the shelf life and consumer acceptance of fortified products were evaluated. The highest ADF were obtained in 3% WP-Y, 1% WP-I and 2% WP-T samples with the dietary fiber contents of 1.98%, 2.12% and 1.83% and RSA of 935.78, 585.60 and 706.67 mg AAE/kg, respectively. WP fortified products had more dietary fiber content than that of LE and FDE fortified ones because of the insoluble fractions. The pH dropped from 4.52 to 4.32 for 3% WP-Y during three weeks of storage at 4 °C, but remained stable in WGP-I and WGP-T samples after four weeks of storage at 4 °C. Adding WGP resulted in 35-65% reduction of PV in all samples compared to the control. In WGP-Y, the viscosity increased, but syneresis and lactic acid percentage were stable during storage. The 1%WP-Y, 0.5%WP-I and 1%WP-T samples were mostly liked by consumers. Study demonstrated that WGP can be used as a functional food ingredient for enhancing nutraceutical content and extending shelf-life of the food products. This study provided important information about the economically feasible drying methods for retaining the bioactive compounds in WGP during processing and storage and also suggested that WGP can be utilized as antioxidant dietary fiber to be fortified in consumer products to promote nutritional benefit and extend product shelf-life. / Graduation date: 2013

The South African wine industry is a significant contributor to the South African economy. However the wine producers are facing financial and operational challenges as they operate and compete in a highly traded local and international wine market. These financial and operational challenges manifest as risks in their supply chain and could affect the future sustainability of their business. It against this backdrop that this study aimed to identify the supply chain risks experienced by the Stellenbosch wine producers, and how they manage and overcome these risks. The research was conducted at five wine producers located in each of five Stellenbosch wine producing areas. The producers were selected through a non-probability purposive sample with the assistance of a gatekeeper. The study is descriptive and exploratory with qualitative data collected through semi-structured interviews with ten participants from the five wine producers. The data was analysed using thematic analysis. The study found that the main risk factors centered around: the planning activities concerning the risks involved in matching demand and supply; agricultural activities including the drought and other external hazard risks; the wine making activities including in-process controls; financial risks including margin erosion due to inflationary costs not being matched by selling price increases; and human resource risks. This study recommends that wine producers use a formal risk appraisal process, implement a supplier development process, could make use of precision viticulture methods and improved pest control measures. / Business Management / M. Com. (Business Management)

Siu, Kit Wah Lydia. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (p. 201-207). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Chapter Chapter 1 --- Introduction --- p.1 / Aim of the Study --- p.1 / Background --- p.3 / Literature Review --- p.10 / """Conspicuous"" Wine Consumption" --- p.14 / Taste as a Combination of Symbols of Class Distinction --- p.17 / "Hong Kong, a City of Consumption" --- p.19 / Methodology --- p.21 / Challenges and Limitations --- p.25 / Summary of the Thesis --- p.26 / Chapter Chapter 2 --- The Wine Market in Hong Kong --- p.28 / Introduction --- p.28 / Consumption and Identity --- p.29 / The Beginning of Wine Consumption in Hong Kong --- p.33 / The Beginning of the Mass Consumption of Wine in the 1960s --- p.36 / Popularization in the 1980s to the Early 1990s --- p.39 / The Years of Turbulence 1997-2002 --- p.40 / The Current Wine Market --- p.44 / General Market Features --- p.46 / Conclusion --- p.48 / Chapter Chapter 3 --- The Wine-Tasting Community in Hong Kong --- p.51 / Introduction --- p.51 / The Meaning of Taste --- p.52 / Who are the People in the Wine Tasting Community? --- p.58 / Gender --- p.59 / Age --- p.60 / Level of Economic Capital --- p.61 / Education level --- p.62 / Four Types of Wine-Tasting Events --- p.64 / Large-scale Public Tasting Events --- p.64 / Medium-scale Tasting Events --- p.67 / Private Wine-tasting Events --- p.69 / Wine dinners --- p.70 / Conclusion --- p.72 / Chapter Chapter 4 --- The Rituals of Wine Tasting as Expressions of Identity --- p.75 / Introduction --- p.75 / "Sight, Aroma and Flavor" --- p.77 / The Practices of Tasting Rituals in Large-Scale Public Wine-Tasting Events. --- p.80 / Assessment of Sight --- p.84 / Assessment of Aroma --- p.85 / Assessment of Flavor --- p.87 / The Final Step: Spitting --- p.88 / Beyond Tasting: Wine Talk --- p.91 / Conclusion --- p.94 / Chapter Chapter 5 --- The Symbols of Social Distinction in Wine Consumption --- p.99 / Introduction --- p.99 / The Relationship of Wine and Social Distinction --- p.100 / Westernness --- p.102 / Uniqueness --- p.105 / Wealth --- p.107 / Knowledge --- p.112 / Leisure --- p.118 / Art and Aestheticism --- p.121 / Health Consciousness --- p.123 / Conclusion --- p.127 / Chapter Chapter 6 --- Wine as Individual Identity --- p.131 / Introduction --- p.131 / Brief Description of YC and its wine group --- p.133 / Setting --- p.133 / Becoming a member of YC --- p.137 / The structure of the YC wine group --- p.139 / The Core Value: Tasting vs Drinking --- p.143 / Taboos in the YC Wine Group --- p.144 / The Role of Alcohol and Intoxication --- p.145 / Demeaning Wine's Taste --- p.149 / Learning about Taste: Hierarchical or Equal? --- p.154 / Objective Evaluation.. --- p.157 / Subjective Appreciation --- p.160 / Searching for Oneself: a Favorite Wine and a Preferred Taste --- p.165 / Conclusion --- p.171 / Chapter Chapter 7 --- Comparing San Francisco and Hong Kong as to Wine --- p.174 / Introduction --- p.174 / Fieldwork in San Francisco --- p.175 / Drinkers´ة society vs Tasters' society --- p.176 / "Drinkers, Tasters and Producers" --- p.179 / Learning to Taste Wine in San Francisco --- p.182 / The Understanding of Wine and Taste in San Francicso --- p.185 / Chapter Chapter 8 --- Conclusion --- p.192 / Chapter Appendix: --- Reference --- p.201

Thesis (MBA)--Stellenbosch University, 2005. / Some digitised pages may appear illegible due to the condition of the original hard copy / ENGLISH ABSTRACT: The international surplus of wine and the strong Rand resulted in tremendous pressure on wine organizations to stay relevant and profitable. The biggest challenge for South African wine organizations are to keep a market oriented focus and manage the value chain costeffectively. This study was undertaken to investigate the structures of value chains used by South African export organizations as well as the way that these organizations function in this environment. To succeed in this goal questionnaires were sent to South African export organizations. Information was analyzed to investigate the positioning and trading terms that were generally used. The structure of value chains was determined as well as the participation of export organizations in demand chains. Data was analyzed to determine if the type of organization and the volume of export had an influence on the positioning of the organization, trading terms and the structure of the value chain. Most export organizations, exported less than 5 000 cases of wine each year and could be classified as small and medium enterprises. The type of organization had an influence on the payment terms as well as the positioning of the products in the market. The country of import mainly influenced the structure of the value chain. Ordering systems were not ideally suited to provide in the changing demand of consumers and a lack in the use of information technology to manage the value chain was apparent. A significant number of organizations were not actively involved in stimulating the consumer to buy their products. Therefore South African wine export organizations are still highly fragmented and do not succeed in managing the value chain as an integrated system. Improved market research should be done before the positioning of products with the focus on profit margins instead of price segments. Information technology should be utilized to reach higher service levels in the value chain and contribute in exceeding the buyer's expectations. / AFRIKAANSE OPSOMMING: Die huidige ooraanbod van wyn op die wêreldmark, tesame met 'n sterk rand, plaas wynprodusente onder geweldige druk om winsgewend en relevant te bly. Die grootste uitdagings vir Suid-Afrikaanse wynondernemings is om waardekettings markgefokus te kry en koste effektief te bestuur. Hierdie studie is onderneem om ondersoek in te stel na die waardekettingstrukture wat gewild is by Suid-Afrikaanse uitvoerondernemings en die wyse waarop die ondernemings daarin funksioneer. Om in hierdie doel te slaag is vraelyste na Suid-Afrikaanse uitvoerondernemings gestuur. Die inligting is verwerk om die posisionering en handelsterme wat ondernemings gebruik te ondersoek. Die struktuur van waardekettings wat na die uitvoerbestemmings gebruik word is bepaal asook die betrokkenheid van uitvoerondernemings by vraagkettings. Data is so ge-orden om te bepaal of die tipe onderneming en die volume botteluitvoere 'n invloed het op die posisionering, handelsterme en die struktuur van waardekettings. Die meeste uitvoerondernemings voer minder as 5 000 kiste per jaar uit en kan as klein en medium organisasies geklassifiseer word. Die tipe onderneming het 'n invloed gehad op betalingsterme wat beding word asook op die pryssegmente waarin wyne geposisioneer word. Die struktuur van waardekettings is hoofsaaklik beïnvloed deur die land waarheen uitgevoer word. Bestel- en versendingsisteme word nie optimaal bestuur nie en die aanwending van inligtingstegnologie om die waardeketting te bestuur kry nie baie aandag nie. Heelwat ondernemings was ook nie aktief betrokke om die verbruiker te stimuleer om sy produkte te koop nie. Suid-Afrikaanse uitvoerondernemings is dus nog baie gefragmenteerd en slaag nie daarin om die waardeketting as 'n geïntegreerde proses te bestuur nie. Beter marknavorsing behoort gedoen te word wanneer wyne posisioneer word met die fokus op winsmarges eerder as pryssegmente. Die beskibare inligtingstegnologie behoort aangewend te word om hoër diensvlakke in die waardeketting te handhaaf en so die verbruiker se verwagtinge te oortref.