Thesis (MA) -- Stellenbosch University, 1932. / VOORWOORD: Die doel van hierdie verhandleing is in die eerste plek om daarop te wys dat in Suid-Afrika meer wyn geproduseer word as wat tans van die hand gesit kan word teen 'n prys wat die produsente genoegsaam sal vergoed. Uit die oorproduksie en die heersende lae pryse volg dit dat die posiesie van die wynboere erg kritiek en haglik is. Die industrie gaan nou juis weer deur diepe waters en iets moet gedoen word om die bedryf van ondergang te red en vir die toekoms op 'n vaste basis te plaas.

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.

Proefskrif (MScAgric)--Stellenbosch University, 1972. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

Thesis (MScAgric)--Stellenbosch University, 1969. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

Thesis (MBA)--Stellenbosch University, 2014. / Scenarios are a strategic tool that can stimulate strategic thinking, generate strategic foresight, provide a basis for testing existing strategies, explore and understand complexities of the future. In so doing they can aid decision making and contribute to preparation for the future. As such, this research paper used scenarios to explore a number of plausible futures for the South African Wine Industry in order to stimulate strategic thinking and conversations, pave the way for new ideas and approaches and encourage innovation. This can prepare both the industry and wine producers for possible challenges that they may face in the future. The scenario development process started with an extensive exploration of the existing industry, which included industry trends and patterns as well as factors within the external environment that influence the strategic landscape. Three key driving forces were identified in the external environment which could potentially have the largest impact on the future of the industry. These are impacts of climate change, local industry consolidation and buying power changes. Five scenarios for the South African Wine Industry were developed for the year 2025 based on these driving forces. These scenarios reflected these key driving forces under different circumstances, which provided different perspectives related to their impacts. The scenarios introduced alternative futures which range from one that envisages a consolidated local wine industry which focuses on the export market as a result of the opportunities presented by extreme weather events resulting from global climate change, to a scenario that is characterised by negligible changes in the structure of the local industry and where high buying power changes the industry dynamics and key success factors. A set of main findings relating to each scenario was formulated. These findings were examined in order to identify implications and make recommendations that could be useful to consider and aid strategy development for the industry, as well as for the benefit of individual wine producers. Key findings related to the impact of these key driving forces as well as the risks and potential opportunities that they could present for the industry under certain circumstances.

Thesis (MSc)--Stellenbosch University, 1934. / No Abstract Available

Thesis (MScAgric)--Stellenbosch University, 1952. / No Abstract Available

Thesis (MScAgric)--Stellenbosch University, 1950. / No Abstract Available

M.Sc. / The origin of a wine plays a key role in establishing the quality and the price the consumer is prepared to pay. Fingerprinting techniques based on multi-element data combined with multivariate statistical analysis as well as isotope ratio data for certain elements such as boron (11B/10B) and strontium (87Sr/86Sr) are being developed and have been used for provenance determination of wine with varying degrees of success. The aim of this study was to develop a method to determine boron isotope ratios (11B/10B) with the required precision using ICP-MS (inductively coupled plasma mass spectrometry) in soil and wine samples and applying this method to establish the origin of South African wines. Analytical difficulties such as the boron memory effect, dead time, mass bias drift and matrix effects were investigated. Although the memory effect, dead time and mass bias drift were satisfactorily resolved, it was not possible to determine what the cause of all the observed matrix effects was during this study. The method was used to categorise wines from the Robertson, Swartland and Stellenbosch regions and an attempt was made to link the measured boron isotope ratios with that obtained from the corresponding provenance soils. The 11B/10B isotope ratios for the wine samples (Robertson: 4.202 ± 0.014, Swartland: 4.173 ± 0.013 and Stellenbosch: 4.174 ± 0.028) were, however, higher than the ratios obtained for the soil samples (Robertson: 4.108 ± 0.020, Swartland: 4.070 ± 0.023 and Stellenbosch: 4.124 ± 0.039). It was possible to distinguish, using the boron isotope ratios (wine and soil samples), between the Robertson area (Breede River region) and the Swartland area (Coastal region). The wine and soil 11B/10B isotope ratios obtained for the Stellenbosch area (Coastal region) overlapped with the 11B/10B isotope ratios of the Robertson and Swartland regions making it impossible to differentiate it from these two regions.

Thesis (MSc Food Sc )--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Highly valued Sauvignon blanc wines, with the distinctive cultivar-typical aromas, reminiscent of grassy, green pepper or asparagus-like, are produced in some South African regions. Quite often, however, neutral and sulphur-like, low quality Sauvignon blanc wines are produced and this phenomenon is of great concern to wine producers and consumers, and affects our competition on overseas markets, negatively. The aim of this study was to investigate the effect of region, ascorbic acid/S02 treatments and yeast strain on Sauvignon blanc wine aroma and quality. Wines were produced from grapes obtained from the warmer Robertson and the relatively cooler Stellenbosch regions (1998 season). The juices were treated with different combinations of ascorbic acid/S02 treatments [commercially available ascorbic acid/meta preparate, S02 (control), pure ascorbic acid/S02] and Saccharomyces cerevisiae yeast strains (Vin 13, VL3C, NT 116). The wines were analysed for esters, higher alcohols, monoterpenes and 2-methoxy-3-isobutylpyrazine (ibMP). The wines were also sensorially evaluated for wine aroma intensities (fruity/ester, sulphur-like, grassy/green pepper) and overall quality. Additionally, the synergistic action of ibMP and the sulphur-containing component, 4-mercapto-4-methylpentan-2- one (MMP), considered to be the most important impact components of Sauvignon blanc, was studied. The two components were added, separately and in combinations at increasing concentrations, to different media. The nuances perceived, varied from dusty, grassy to green pepper for ibMP and from guava, sulphur-like to cat urine or "conifer" for MMP. Significant differences were observed between the wines treated with the different combinations of ascorbic acid/S02 treatments and fermented with different yeast strains, irrespective of region. The highest quality, cultivar-typical Sauvignon blanc wines were produced from the pure ascorbic acid/S02 treatment in combination with yeast strains Vin 13 and NT 116. This coincided with high ester and low higher alcohol concentrations, which did not overpower the typical Sauvignon blanc character. The treatments had, in some cases, a significant effect on monoterpene levels, but it was concluded that these differences were not big enough to affect wine quality. Levels of ibMP were too low and could not be reliably measured. Low quality wines, with prominent, undesirable sulphur-like aromas, were produced from juices, treated with the commercially available ascorbic acid/meta preparate and the French yeast strain, VL3C. Techniques, followed to identify the aroma components causing the sulphur-like offflavours, as MMP or as other sulphur-containing components, were gas chromatography/mass spectrometry, solid phase microextraction and sniffing. However, these tests were not successful and studies to identify these off-flavours should be continued. It was succeeded in this study to produce Sauvignon blanc wines without the undesirable, sulphur-like aromas. Although this investigation showed that a newly developed, commercially available ascorbic acid/meta preparate did not yield any sulphur-like off-flavours, quite often Sauvignon blanc wines with such off-flavours are still produced. Further research is needed to clarify this phenomenon. / AFRIKAANSE OPSOMMING: Hoë kwaliteit Sauvignon blanc wyne, met kenmerkende kultivar-tipiese, gras-, groenrissie- of aspersie-agtige aromas, word in sekere streke van Suid Afrika geproduseer. Die gereelde produksie van neutrale, en swawelagtige lae kwaliteit Sauvignon blanc wyne, wek egter nie net groot kommer by wynprodusente en verbruikers nie, maar het ook 'n negatiewe impak op kompetisie met oorsese markte. Die doel van hierdie studie was dus om die effek van streek, askorbiensuur/Sóbehandelings en gisras op Sauvignon blanc wynaroma en kwaliteit vas te stel. Wyne is berei met druiwe wat verkry is van die warmer Roberston en relatief koeler Stellenbosch streke (1998 seisoen). Verskillende kombinasies askorbiensuur/So, behandelings [kommersieel-beskikbare askorbiensuur/meta preparaat, S02 (kontrole), suiwer askorbiensuur/So-l en Saccharomyces cerevisiae gisrasse (Vin 13, VL3C, NT 116) is gebruik tydens die wynbereidingsproses. Spesifieke ester-, hoër alkohol-, monoterpeen- en 2-metoksi-3-isobutiel metoksipirasienkonsentrasies (ibMP) is in die wyne bepaal. Die wyne is ook sensories vir wynaroma intensiteite (vrugtig/ester, swaweiagtig, gras/groenrissie-agtig) en algehele kwaliteit geëvalueer. Die sinergistiese aksie van ibMP en die swawelbevattende komponent, 4-merkapto- 4-metielpenta-2-oon (MMP), wat beskou word as die belangrikste impakkomponente in Sauvignon blanc, is addisioneel bestudeer. Hierdie komponente is in toenemende konsentrasies, individueel en in kombinasies, tot verskillende media gevoeg. Die nuanses wat waargeneem is, het van stowwerig, gras-, groenrissie-agtig vir ibMP, tot koejawelagtig, swaweiagtig, katurine, konifeer vir MMP, gevarieer. Ongeag streke, is betekenisvolle verskille tussen die wyne wat berei is met die verskillende kombinasies van askorbiensuur/So- behandelings en gisrasse, waargeneem. Hoër kwaliteit, kultivar-tipiese Sauvignon blanc wyne is berei met suiwer askorbiensuur/So- in kombinasie met gisras Vin 13 of NT 116. Alhoewel die hoë ester- en lae hoër alkohol- konsentrasies, hierdie resultate bevestig het, is die tipiese Sauvignon blanc karakter nie hierdeur oorheers nie. Sommige behandelings het wel 'n betekenisvolle invloed of monoterpeenkonsentrasies gehad het, maar was te min om 'n effek op wynkwaliteit uit te oefen nie. Die konsentrasievlakke van ibMP swawelagtige aromas, het egter voorgekom in wyne wat met die kommersieelbeskikbare askorbiensuur/meta preparaat en die Franse gisras, VL3C, berei is. Verskeie tegnieke soos gaschromatografie/massa spektrometrie, soliede fase mikroekstraksie en "sniffing", is gebruik om die komponent, MMP, wat moontlik verantwoordelik vir hierdie ongewensde swawelagtige wangeure was, te identifiseer. Die identifikasie hiervan was egter onsuksesvol, en verdere studies is nodig om die komponent(e) verantwoordelik vir hierdie wangeure, te identifiseer. Die suksesvolle produksie van Sauvignon blanc, sonder ongewensde swaweiagtig aromas, was wel moontlik. Alhoewel hierdie studie ook duidelik getoon het dat daar geen swawelagtige wangeure in die wyne wat met die nuut ontwikkelde, kommersieel-beskikbare askorbiensuur/meta preparaat berei was, voorgekom het nie, vind die produksie van Sauvignon blanc wyne met van hierdie wangeure nog steeds plaas. Verdere navorsing rakende hierdie aspek is nodig.