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

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

Constituents of the wine matrix, including ethanol, affect adsorption of sulfur volatiles on solid-phase microextraction (SPME) fibers, which can impact sensitivity and accuracy of volatile sulfur analysis in wine. Several common wine sulfur volatiles, including hydrogen sulfide (H2S), methanethiol (MeSH), dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), diethyl disulfide (DEDS), methyl thioacetate (MeSOAc), and ethyl thioacetate (EtSOAc), have been analyzed with multiple internal standards using SPME-GC equipped with pulsed-flame photometric detection (PFPD) at various concentrations of ethanol, volatile-, and non-volatile-matrix components in synthetic wine samples. All compounds exhibit a stark decrease in detectability with the addition of ethanol, especially between 0.0 and 0.5%v/v, but the ratio of standard to internal standard was more stable when alcohol concentration was greater than 1%. Addition of volatile matrix components yields a similar decrease but the standard-to-internal-standard ratio was consistent, suggesting the volatile matrix did not affect the quantification of volatile sulfur compounds in wine. Non-volatile wine matrix appears to have negligible effect on sensitivity. Based on analyte:internal standard ratios, DMS can be accurately measured against ethyl methyl sulfide (EMS), the thioacetates and DMDS with diethyl sulfide (DES), and H₂S, MeSH, DEDS, and DMTS with diisopropyl disulfide (DIDS) in wine with proper dilution. The developed method was then used to quantify sulfur compounds in 21 various California wines. H₂S and MeSH were found in higher concentrations in white varietals, while DMS was slightly higher in red varietals, particularly cabernet sauvignon and merlot. Trace amounts of DEDS and MeSOAc were found in almost all wines. DMS and DMTS were found in all wines, in some instances above reported thresholds. / Graduation date: 2012

This thesis presents a systematic investigation ofyeasts associated with wine grapes cultivated in several Australian vineyards during the 2001-2003 vintages. Using a combination of cultural and molecular methods, yeast populations of red (Cabernet sauvignon, Merlot, Tyrian) and white (Sauvignon blanc, Semilion) grape varieties were examined throughout grape cultivation. The yeast-like fungus, Aureobasidium pullulans, was the most prevalent species found on grapes. Various species of Cryptococcus, Rhodotorula and Sporobolomyces were frequently isolated throughout grape maturation. Ripe grapes showed an increased incidence of Hanseniaspora and Metschnikowia species for the 2001-2002 seasons, but not for the drought affected, 2002-2003 seasons. Atypical, hot and dry conditions may account for this difference in yeast flora and have limited comparisons of data to determine the influences of vineyard location, grape variety and pesticide applications on the yeast ecology. More systematic and controlled studies of these variables are required. Damaged grape berries harboured higher yeast populations and species diversity than intact healthy berries. PCR-DGGE analysis was less sensitive than plate culture for describing the diversity of yeast species on grapes; it detected prevalent species, but subdominant populations below 103 CFU/g were not detected. In some cases, PCR-DGGE revealed the presence ofyeasts (Candida galli, C. zemplinina) not isolated by culture. Fermentative wine species (Kluyveromyces, Torulaspora, Saccharomyces) were rarely isolated, and only detected by enrichment cultures. Significant morphological and genetic variability were detected among A. pullulans and other black yeasts isolates from grapes. Taxonomic characterization of 61 strains by ITS-RFLP and rDNA sequencing revealed that they belonged to several distinct species within the generic groupings ofAureobasidium, Hormonema and Kabatiella. Isolates were strong producers of extracellular enzymes and polysaccharides that could have oenological significance, and, using a plate assay, some were antagonistic towards Bacillus thuringiensis, several wine yeasts, and some spoilage and mycotoxigenic fungi found on grapes. Growth of Saccharomyces cerevisiae was not inhibited by these organisms in grape juice. A species-specific probe was developed for the identification of the wine spoilage yeast, Zygosaccharomyces bailii in a microtitre plate hybridization assay. The probe detected 102 cells/ml in wine, reliably differentiating Z. bailii from other Zygosaccharomyces and other wine-related yeasts.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2001. / Includes bibliographical references.

Thesis (MSc)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (MScFoodSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Twenty five commercial Chenin blanc wines produced solely from bush vine vineyards and including three vintages, three styles and five production areas, were sourced for this study. Descriptive sensory analysis (DSA) and chemical analyses including GC-FID (gas chromatography fitted with a flame ionisation detector) and FTMIR (Fourier transform mid-infrared) spectroscopy were employed to establish the sensory and chemical characteristics, whereas consumer tests were conducted to determine consumer perception and liking of bush vine Chenin blanc wines. DSA (a profiling technique) was also compared to the sorting task (a classification technique) with a description assignment to evaluate the sorting task’s ability to profile wines. According to the results of DSA, the wines separated into two groups. One group associated with sensory attributes which can be considered indicative of the Fresh and Fruity Chenin blanc style. The other group associated with sensory attributes which can be considered indicative of the Rich and Ripe style of Chenin blanc. No separation between the wooded and unwooded Rich and Ripe styles was apparent. According to the results of the chemical analyses, the wines also separated into two groups. This separation seemed to be caused by vintage and the chemical changes associated with ageing as the wines from the youngest vintage (2010) was strongly associated with high levels of esters and malic acid. The older wines were situated farthest away from these attributes indicating low concentrations. When comparing the results from the sorting task and DSA, it could be seen that similar wine style groupings formed, indicating that DSA can also be regarded as an effective tool when categorising wines. The differences in the positioning of some of the wines and attributes on the DSA multivariate plots and the sorting task plots could be attributed to the difference in panels used. The sorting task was conducted using an expert panel with persons illustrating significant technical knowledge of Chenin blanc wines. Experience, exposure and technical knowledge tend to establish a common language amongst wine experts which could have caused the expert panel to perceive some wines differently when comparing the results of the latter panel to that of the trained panel. DSA was found to remain the most effective method for establishing a comprehensive sensory profile. Consumer analyses showed that regular white wine drinkers prefer the unwooded styles (Fresh and Fruity and Rich and Ripe unwooded) of Chenin blanc more than the wooded style. It was also found that consumers with a higher level of objective wine knowledge tend to associate the terms ‘bush vine’ and ‘old bush vine’ with the Rich and Ripe style of Chenin blanc, whereas consumers with a lower level of objective wine knowledge associated ‘old bush vine’ with the Fresh and Fruity style. Since all the wines used in the consumer analysis were produced from old bush vines, it is evident that consumer education on the impact of bush vine training system and vine age on wine quality is needed. Better understanding of these principles could lead to elevated product appraisals and consumer satisfaction. / AFRIKAANSE OPSOMMING: Vyf en twintig kommersiële Chenin blanc wyne, uitsluitlik van bosstok wingerde geproduseer, is bekom vir hierdie studie. Die wyne het drie style, drie oesjare en vyf produksiestreke ingesluit. Beskrywende sensoriese analise (BSA) en chemiese analises, wat GC-FID (gas chromatografie gekoppel met vlam-ioniserende deteksie) en FTMIR (Fourier-transformering mid-infrarooi) spektroskopie insluit, is uitgevoer om onderskeidelik die sensoriese en chemiese eienskappe van die wyne te bepaal. Verbruikerstoetse is ook uitgevoer om verbruikerspersepsie en -voorkeure vir bosstok Chenin blanc wyne te bepaal. BSA (‘n profilerings tegniek) was ook vergelyk met ‘n sorterings taak (‘n klassifikasie tegniek) met ‘n beskrywings opdrag, primêr om die sorterings taak se vermoë om wyne te profileer te ondersoek. Volgens die resultate van BSA, het die wyne in twee groepe verdeel. Een groep het met die sensoriese eienskappe wat op ‘n Vars-en-Vrugtige-styl dui, geassosieër. Die ander groep het met sensoriese eienskappe geassosieër wat met die Volrond-styl verband hou. Geen verdeling tussen die gehoute en ongehoute wyne binne die Volrond-styl was sigbaar nie. Volgens die resultate van die chemiese analises, het die wyne ook in twee groepe verdeel. Die verdeling blyk asof dit veroorsaak is deur oesjaar en die chemiese veranderinge wat met wynveroudering gepaard gaan. Wyne van die jongste oesjaar (2010) het ‘n sterk verband met hoë vlakke van esters en appelsuur getoon. Die ouer wyne was verder weg van hierdie eienskappe geleë, wat op laer ester en appelsuur konsentrasies dui. Wanneer die meerveranderlike resultate van die sorterings taak (met en sonder die aanduiding van sensoriese eienskappe) en dit van BSA vergelyk word, kon soortgelyke groeperings gesien word. Dit is ‘n aanduiding dat BSA ook wyne effektief kan kategoriseer. Die verskil in posisionering van sommige wyne tussen die BSA en sorterings taak resultate, kan toegeskryf word aan die verskillende panele wat gebruik is om die tegnieke uit te voer. ‘n Deskundige paneel (wynkenners) is gebruik om die sortingstaak uit te voer. Ervaring, blootstelling en tegniese kennis is geneig om te lei tot die vestiging van ‘n gemeenskaplike taal onder wynkenners. Hierdie gemeenskaplike taal kan as rede aangevoer word vir die uiteenlopende analise van sommige wyne wanneer die resultate van die deskundige paneel met dié van die opgeleide paneel (in BSA gebruik) vergelyk word. Dit is gevind dat BSA, wanneer ‘n omvattende sensoriese profiel bepaal moet word, die mees effektiefste metode bly. Verbruikerstoetse het getoon dat gereelde witwyn-verbruikers die ongehoute Chenin blanc style (Vars-en-Vrugtig en ongehoute Volrond) bo die gehoute styl verkies. Dit is ook bepaal dat verbruikers met ‘n hoër vlak van objektiewe wynkennis neig om die terme ‘bosstok’ en ‘ou bosstok’ met die Volrond-styl van Chenin blanc te assosieer, terwyl verbruikers met ‘n laer vlak van objektiewe wynkennis die term ‘ou bosstok’ met die Vars-en-Vrugtige Chenin blanc styl assosieër. Aangesien al die wyne wat in die verbruikerstoetse ingesluit is van ou bosstok wingerde geproduseer is, is dit duidelik dat verbruikeropvoeding insake die effek van die gebruik van bosstokke en ou wingerdstokke op wynkwaliteit noodsaaklik is. ‘n Beter begrip van hierdie beginsels sal lei tot verhoogde produkwaardasie, asook ‘n toename in verbruikertevredenheid.

Thesis (MSc Food Sc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: South Africa is a developing country that relies on its agricultural sector as a main source of overall economic welfare. Development does not only give rise to new technology and new products but also results in increased amounts of liquid and solid waste. Generally, the production of wine is considered an environmentally friendly process, but significant amounts of natural resources and organic amendments are necessary, while generating large amounts of liquid and solid wastes. Anaerobic digestion (AD) is an attractive and proven treatment option for both liquid and solid wastes as valuable products and depollution can be obtained. AD of liquid waste results in an effluent and biogas, while anaerobic composting of solid waste results in an organic amendment, leachate and biogas. The overall objective of this study was to investigate the operational feasibility of the cotreatment of leachate produced during the anaerobic composting (AnC) of grape skins in an upflow anaerobic sludge blanket (UASB) reactor while treating winery wastewater. This first aim of this study was to investigate the efficiency of the anaerobic composting of grape skins. Laboratoryscaled digesters (1L) were utilised as anaerobic composting units. The most important operational parameters were identified (pH, moisture content and inoculum (size, ratio, composition)) in order to produce a pH stable, odour free compost in 21 days. Experimental studies highlighted the importance of shredding waste as well as the addition of calcium oxide and green waste to increase the initial pH of the composting mixture. After optimising a 50% (m.m-1) cow manure inoculum, lower inoculum concentrations (10, 15 and 25% (m.m-1)) were investigated to make the process more economically viable. A 10% (m.m-1) anaerobic compost (AC) inoculum was found to produce the most favourable results in terms of pH stabilisation and leachate generation. A 50% (m.m-1) moisture level performed the best by attaining a pH > 6.5 on day 6 and having the highest end pH (7.65) on day 21, while white and red grape skins in an equal ratio were found to generate a higher end pH. With all these optimum parameters in place (shredded waste, green waste, CaO, inoculum, moisture, grape skins), a compost with a final pH (7.09), moisture (58%), nitrogen (2.25%), phosphorous (0.22%) and potassium content (1.7%) was obtained. The optimised parameters were scaled-up (1:10) by using polyvinyl chloride anaerobic digesters (20 L) to suit the operational requirements of the AnC process and also produced a stable compost within 21 days. The second aim of this study was to investigate the combined anaerobic digestion of winery wastewater (WWW) and leachate obtained from the anaerobic composting of grape skins in an upflow anaerobic sludge blanket (UASB). This involved the operation of a 2.3 L laboratory-scale UASB reactor for 205 days. The reactor successfully co-treated WWW and leachate at ca. 8.5 kgCOD.m-3d-1 with a final chemical oxygen demand (COD) reduction of over 90%, a stable reactor effluent pH (7.61) and alkalinity (3 281 CaCO3 mg.L-1). This study showed the feasibility for the combined treatment of liquid and solid waste from the winemaking process. Although the legal limits for reactor effluent disposal onto land was not met, significant reduction in COD concentrations were achieved, whilst producing a soil amendment that could potentially result in cost savings for chemical fertilisers. The benefits related to using anaerobic bioconversion as a treatment option for liquid and solid waste could possibly be advantageous to the wine industry as an environmental control technology, by converting liquid and solid waste into valuable resources. / AFRIKAANSE OPSOMMING: Suid-Afrika is 'n ontwikkelende land wat staatmaak op sy landbousektor as 'n hoofbron van algehele ekonomiese welstand. Ontwikkeling gee nie net aanleiding tot nuwe tegnologie en nuwe produkte nie, maar lei ook tot die verhoogde bydrae van vloeistof sowel as vaste afval. Oor die algemeen, word die produksie van wyn beskou as 'n omgewingsvriendelike proses, maar aansienlike hoeveelhede natuurlike hulpbronne en organiese kunsbemesting word benodig, terwyl groot hoeveelhede vloeistof en vaste afval gegenereer word. Anaërobiese vertering (AV) is 'n aantreklike en bewese behandelingsopsie vir beide vloeistof en vaste afval aangesien waardevolle produkte en suiwering verkry kan word. AV van vloeistowwe lewer uitvloeisel sowel as biogas, terwyl anaërobiese kompostering van vaste afval 'n organiese kunsbemesting, loog en biogas lewer. Die oorhoofse doel van hierdie studie was om die operasionele doeltreffendheid van die mede-behandeling van loog wat gegenereer word tydens die anaërobiese kompostering (AnK) van druiwe doppe in 'n opvloei-anaërobiese-slykkombers (OAS) reaktor terwyl kelderafvalwater behandel word, te ondersoek. Die eerste mikpunt van hierdie studie was om die doeltreffendheid van die anaërobiese komposteringsproses van druiwe doppe te ondersoek. Laboratorium-skaal verteerders (1L) is gebruik as anaërobiese komposteringseenhede. Die belangrikste operasionele parameters is geïdentifiseer (pH, voginhoud en inokulum (grootte, verhouding, samestelling)) om ‘n 'n pH-stabiele, reukvrye kompos te produseer in 21 dae. Die belangrikheid van gesnipperde afval asook die byvoeging van kalsiumoksied en groen afval om die aanvanklike pH van die komposmengsel te verhoog, is deur eksperimentele studies beklemtoom. Na die optimering van 'n 50% (m.m-1) koeimis inokulum, is laer inokulum konsentrasies (10, 15 en 25% (m.m-1)) geondersoek om die proses meer ekonomies uitvoerbaar te maak. Daar is gevind dat ‘n 10% (m.m-1) anaërobiese kompos (AK) inokulum die mees gunstige resultate lewer in terme van pH stabilisering en loog generering. ‘n 50% (m.m-1) vloeistof vlak het die beste presteer deur 'n pH> 6.5 te bereik teen Dag 6 asook die hoogste eind pH (7.65) teen Dag 21, terwyl wit en rooi druiwe doppe in dieselfde verhouding gevind is om ‘n hoër eind pH te genereer. Met al hierdie optimum parameters in plek (gesnipperde afval, groen afval, kalsiumoksied, inokulum, vog, druiwe doppe) is 'n kompos met 'n finale pH (7.09), vog (58%), stikstof (2.25%), fosfor (0.22%) en kalium inhoud (1.7%) verkry. Die optimale parameters is opgeskaal (1:10) deur gebruik te maak van polivinielchloried anaërobiese verteerders (20 L) om aan die operasionele vereistes van die AnK proses te voldoen en ook om 'n stabiele kompos binne 21 dae te produseer. Die tweede mikpunt van hierdie studie was om die gekombineerde anaërobiese vertering van kelderafvalwater en loog, verkry vanaf die anaërobiese kompos van druiwe doppe in 'n OAS reaktor, te ondersoek. Dit het die bedryf van 'n 2.3 L laboratorium-skaal OAS reaktor vir 205 dae ingesluit. Die reaktor het kelderafwater en loog suksesvol behandel by ongeveer 8.5 kgCSV.m-3d-1 met 'n finale chemiese suurstof vereiste (CSV) vermindering van meer as 90%, 'n stabiele reaktor uitvloeisel pH (7.61) en alkaliniteit (3 281 CaCO3mg.L-1). Hierdie studie het die uitvoerbaarheid van die gekombineerde behandeling van vloeistof en vaste afval van die wynmaakproses getoon. Alhoewel die wetlike vereistes van die reaktor uitvloeisel vir storting op grond nie bereik is nie, is ‘n beduidende vermindering in CSV konsentrasies bereik, asook die vervaardiging van kunsbemesting wat die potensiële aankoopkoste van chemiese kunsmis kan verminder. Die voordele verbonde aan die gebruik van anaërobiese bio-omskakeling as 'n behandelingsopsie vir vloeistof en vaste afval kan moontlik voordelig wees vir die wynbedryf as 'n omgewingsbeheerende tegnologie deur om vloeistof en vaste afval om te skakel na waardevolle bronne.

Thesis (MSc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The importance of indigenous fruit wines is not well researched and documented. There is a need to develop and exploit these valuable food resources through improved production practices, storage, preservation and utilization technologies. The maruia fruit is beneficial in many ways, it can be used for making juice, jam, beer or can be eaten as a whole fruit. The highly nutritive nature of the fruit, its distinctive tropical flavor, its wild occurrence and demand by the local and international communities for the by-products of the fruit necessitated efforts to optimize the technological processes for the production of the possible by-products. This study focuses on the fermentation technology of the maruia fruit. The effect of enzymes prior to the fermentation process and post-fermentation was evaluated. For pre-fermentation processes we focused on the ability of commercial enzymes to increase juice yield, improve the clarification and filterability. For pre- and post-fermentation applications, aroma release was considered. The results indicated a significant increase in the yield depending on the enzyme used. An increase of at least 2% was recorded and a maximum of 12% yield increase was observed. The enzymes also had a phenomenal effect on the release of bound monoterpenes and hence enhancing the flavor of the juice. The panel of judges confirmed the results from the gas chromatography analyses by noting an increase in flavor intensity in the enzyme treated juice. The possibility of selecting a yeast strain that performs best during the fermentation of maruia pulp was also looked at. This study aimed at selecting a strain that produces wine and distillate with the typical maruia flavor complex. We showed the effect of the different yeast strains, in the wines and distillates, on the principal volatile compounds. We then correlated the performance of the different strains as perceived by the panel to the various volatile compounds. The effect of fermentation temperature on the performance of the different yeast strains was also considered. Fermenting the maruia pulp at different temperatures resulted in the production of wines and distillates with different volatile profiles for the different yeast strains. The wines and distillates fermented at a low temperature of 15°C were preferred to the wines and distillates fermented at 30°C. However, not all strains performed well at 15°C, strains like NT116 performed better at 30°C. The different commercial strains produced wines and distillates with significantly different flavor profiles. These differences in the flavor profiles were reflected in the sensory evaluation where, depending on the interaction of the volatile compounds some wines and distillates were preferred to others. The effect of the different commercial enzymes and yeast strains should thereof be further evaluated and optimized on a larger scale. This would greatly help prevent variation in quality of the fermented by-products of the maruia fruit. / AFRIKAANSE OPSOMMING: Die belang van inheemse vrugtewyne is nie goed nagevors en gedokumenteer nie. Daar is 'n behoefte om hierdie waardevolle voedselbronne te ontwikkel en te benut, deur verbeterde produksiepraktyke, storing, preservering en benuttingstegnologieë. Die maroelavrug is veelsydig op baie wyses, deurdat dit gebruik word vir die maak van sap, konfyt, bier, of as heel vrug geëet kan word. Die vrug is hoog in voedingswaarde, het In kenmerkende tropiese geur, kom wild voor, en is in aanvraag by plaaslike en internasionale gemeenskappe vir die by-produkte van die vrug. Dit maak dit essensieel om die tegnologiese prosesse vir die produksie van hierdie moontlike by-produkte te optimiseer. Hierdie studie fokus op die fermentasie-tegnologie van die maroelavrug. Die effek van ensieme voor en na die fermentasie-proses is geëvalueer. Vir prosesse wat voor fermentasie plaasvind, het ons gefokus op die vermoë van kommersiële ensieme om sapopbrengs te verhoog, asook om verheldering en filtrering te verbeter. Vir beide voor- en na-fermentasie toepassings is die vrystelling van aroma gemonitor. Die resultate dui op 'n betekenisvolle verhoging in die sapopbrengs, afhangende van die ensiem wat gebruik is. 'n Verhoging van ten minste 2% is opgeteken, en 'n maksimum van 12% opbrengsverhoging is waargeneem. Die ensieme het ook 'n geweldige effek op die vrystelling van gebonde monoterpene gehad, en dus die verhoging in die geur van die sap. Die proepaneel het die resultate bevestig van die gaschromatografie-analises, deur 'n verhoging in die geurintensiteit in die ensiembehandelde sap te bemerk. Daar is ook gekyk na die moontlikheid om 'n gisras te selekteer wat die beste presteer tydens die fermentasie van maroela-pulp. Hierdie studie het die doelstelling gehad om In gisras te selekteer wat wyn en distillaat produseer met In tipiese maroelageurkompleks. Ons het die effek van verskillende gisrasse aangedui in die wyne en distillate, op grond van van vlugtige komponente. Ons het dan die prestasie van die verskillende rasse, soos waargeneem deur die paneel, gekorrelleer met die verskeie vlugtige komponente. Die effek van fermentasie-temperatuur op die werkverrigting van die verskillende gisrasse is ook in ag geneem. Fermentasie van die maroela-pulp by verskillende temperature het gelei tot die produksie van wyne en distillate met verskillende vlugtige profiele vir die verskillende gisrasse. Die wyne en distillate wat by In laer temperatuur van 15°C gefermenteer is, is verkies bo die wyne en distillate wat by 30°C gefermenteer is. Alle rasse het egter nie baie goed presteer by 15°C nie, soos byvoorbeeld NT116 wat beter presteer het by 30°C. Die verskillende kommersiële rasse het wyne en distillate geproduseer met betekenisvol verskillende geurprofiele. Hierdie verskille in geurprofiele is gereflekteer in die sensoriese evaluering waar, afhangende van die interaksie van die vlugtige komponente, sommige wyne en distillate bo ander verkies is. Die effek van die verskillende kommersiële ensieme en gisrasse moet verkieslik verder op groter skaal geëvalueer en geoptimiseer word. Dit sal veral help om variasie in kwaliteit van die gefermenteerde by-produkte van die maroelavrug te voorkom.

Thesis (MSc)--Stellenbosch University, 1990. / ENGLISH ABSTRACT: To remain competitive in the market place, the South African wine industry will have to direct well-planned yeast strain-development programmes. However, the winemaker can only benefit from the extensive biochemical and molecular information of the yeast cell and the impressive arsenal of genetic techniques available, if the wine industry defines its requirements in genetic terms. The successful application of these genetic and recombinant deoxyribonucleic acid (DNA) techniques in breeding programmes depends on the availability of rapid and reliable techniques to differentiate between parental and hybrid strains. Ten strains of Saccharomyces cerevisiae used for commercial production of wine in South Africa, were characterised by electrophoretic banding patterns of total soluble cell proteins, DNA restriction fragments and chromosomal DNA. Variations in the protein and DNA profiles of strains N6, N21, N66, N76, N95 and N97 were apparent in the number, position and intensity of the bands. Strains N93 and N181 originated from the same culture and, as expected, displayed the same characteristic protein, DNA restriction fragment and chromosomal banding patterns. Similar protein and DNA profiles were also obtained for killer strain N96 and strain N91. Strain N91 is a derivative of strain N96, cured of the K2 killer character. Results obtained by electrophoretic fingerprinting and karyotyping corresponded well, indicating that these techniques are valuable in the identification and quality control of industrial wine yeasts. The value of electrophoretic fingerprinting and karyotyping was also demonstrated in a breeding programme. The aim of this breeding programme was to obtain hybrids that combine the desired oenological characteristics of strains N76 and N96, and of strains N96 and N181. The protein banding patterns of hybrids USM21, USM22 and USM23 were identical and contained a combination of prominent unique bands present in the profiles of parental strains, N76 and N96H (N96H is a haploid derived from N96). The DNA restriction fragment profiles of hybrids USM21, USM22 and USM23 contained slight variations, whereas their profiles were quite different from those of their parental strains, N76 and N96H. The contour clamped homogeneous electric field (CHEF) karyotypes of hybrids USM21, USM22 and USM23 were identical but differed from those of their parental strains, N76 and N96H. The protein profiles of hybrid USM30 and its parental strains, N96H and N181, were similar, whereas their DNA restriction fragment banding patterns and CHEF karyotypes showed discrete differences. In conclusion, protein and DNA fingerprinting techniques were found to be valuable in selecting four hybrid killer strains after mass spore-cell mating. These four killer hybrids contain desirable oenological properties long sought after by the South African wine industry. Fermentation trials and evaluation of these hybrids were conducted independently by the Deparment of Oenology, University of Stellenbosch and by Stellenbosch Farmers' Winery and they have now been released for commercial wine production. / AFRIKAANSE OPSOMMING: Om mededingend in die handel te bly, sal die Suid-Afrikaanse wynbedryf weloorwoe gisras-ontwikkelingsprogramme moet loads. Die wynmaker sal egter slegs voordeel kan trek uit die omvattende biochemiese en molekul...Lre inligting oor die gissel en die indrukwekkende arsenaal van genetiese tegnieke wat beskikbaar is, indien die wynbedryf sy vereistes in genetiese terme definieer. Die suksesvolle toepassing van hierdie genetiese en rekombinante deoksiribonuklei"ensuur (DNA) tegnieke in telingsprogramme sal afhang van die beskikbaarheid van vinnige en betroubare tegnieke om tussen ouerlike en hibried-rasse te onderskei. Tien rasse van Saccharomyces cerevisiae wat vir kommersiele wynproduksie in Suid-Afrika gebruik word, is met behulp van elektroforetiese bandpatrone van totale oplosbare selprotei"ene, DNA-restriksiefragmente en chromosomale DNA gekarakteriseer. Variasies in die protei"en- en DNA-profiele van rasse N6, N21, N66, N76, N95 en N97 het geblyk uit die aantal, posisie en intensiteit van die bande. Rasse N93 en N181 het uit dieselfde kultuur ontstaan en het, soos verwag, dieselfde karakteristieke protei"en-, DNA-restriksiefragmenten chromosomale bandpatrone getoon. Soortgelyke protei"en en DNA profiele is ook vir killerras N96 en ras N91 verkry. Ras N91 is 'n variant van ras N96 wat die K2 killerkenmerk verloor het. Resultate wat met behulp van elektroforetiese vingermerking en kariotipering verkry is, het goed ooreengestem en dui daarop dat hierdie tegnieke waardevol is vir die identifisering en beheer van industriele giste. Die waarde van elektroforetiese vingermerking en kariotipering in telingsprogramme is ook gedemonstreer. Die doel van hierdie telingsprogram was om hibriede te kry waarin die gewenste kenmerke van rasse N76 en N96, en van rasse N96 en N181, gekombineer is. Die protei"en-bandpatrone van hibriede USM21, USM22 en USM23 was identies en het 'n kombinasie van prominente unieke bande, teenwoordig in die profiele van hul ourlike rasse, N76 en N96H (N96H is 'n haploi"de afstammeling van N96), bevat. Die DNArestriksiefragment- profiele van hibriede USM21, USM22 en USM23 toon geringe onderlinge verskille, maar hul profiele het wesenlik van die van hul ouerlike rasse, N76 en N96H, verskil. Die kontoergeklampde-homogene-elektriese-veld (CHEF) elektroforetiese kariotipes van hibriede USM21, USM22 en USM23 was identies, maar het verskil van die van hul ouerlike rasse, N76 en N96H. Die protei"enprofiele van hibried USM30 en sy ouerlike rasse, N96H en N181, was soortgelyk, terwyl hul DNA-restriksiefragment-bandpatrone en CHEF-kariotipes diskrete verskille getoon het. Ten slotte is gevind dat prote'ien- en DNAvingermerkingstegnieke waardevol was in die seleksie van vier hibried-killerrasse na massa spoor-sel paring. Hierdie vier killerhibriede beskik oor gewenste wynkundige eienskappe waarna die Suid-Afrikaanse wynbedryf reeds lank soek. Fermentasie-proewe en evaluering is onafhanklik deur die Departement Wynkunde, Universitiet van Stellenbosch en deur Stellenbosch-Boerewynmakery gedoen en hulle is nou vir kommersiele wynproduksie vrygestel.