Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Wine quality is greatly influenced by the number of microorganisms, which occur throughout the winemaking process. Yeasts are responsible for the alcoholic fermentation, the lactic acid bacteria (LAB) are responsible for malolactic fermentation (MLF), while acetic acid bacteria (AAB) are responsible for converting ethanol to acetic acid. These microorganisms are present on the grapes and in the cellar and these consequently serve as gateways to the fermentation tanks where they will affect the wine quality. However, these microorganisms can be seen either as beneficial or as wine spoilage microorganisms, depending on the conditions that prevail throughout the winemaking process. It is thus very important to prevent any process that could lead to the lowering of the wine quality. In this regard, some of the factors that should always be evaluated include the quality of the grapes, winemaking techniques and quality control. One of the measures that have been implemented during winemaking to ensure the microbial stability is the use of chemical preservatives. Sulphur dioxide (502) has been, and is, used widely as primary preservative in winemaking. However, an ever-increasing consumer resistance against the use of chemical preservatives has developed as it poses possible health risks and decreases the sensorial quality of wine. An alternative approach to chemical preservation that has triggered numerous new investigations, is biological preservation or biopreservation. This is the use of the natural microbial flora and/or their antimicrobial products, such as bacteriocins, to inhibit or destroy the other sensitive microorganisms that are unwanted in the same environment. Evidence in the wine industry has shown that bacterial spoilage still is a very common problem in many wineries. This bacterial spoilage can lead to, amongst other, two main problems, which are of great concern to winemakers. This include high levels of volatile acidity, resulting in the wine having a vinegary off-flavour, and sluggish/stuck fermentation, which is the result of compounds such as acetic- and other fatty acids that causes inhibition of the yeast's growth. With acetic acid being the common link in both cases, it became evident that investigations should be performed on the main producer of acetic acid, namely AAB. As a result, AAB turned out to be one of the main spoilage microorganisms associated with winemaking. Most of the research on biopreservation in the food and beverage industry has been performed on the Gram-positive LAB. The fact that their spectrum of inhibition currently excludes most Gram-negative bacteria, specifically AAB, indicated that AAB should be screened in search of possible antimicrobial compounds that could be applied to control their cell numbers during winemaking. No evidence of antimicrobial action amongst AAB could be found in literature, therefore this work was considered novel. The main objectives of this study were to screen wine isolates of AAB for the production of antimicrobial compounds. This was followed by the isolation and preliminary characterisation of the antimicrobial substances produced. Various attempts to optimise the production of the antimicrobial compounds and isolation procedures, were also included. This study forms part of a larger research programme that has been initiated at the Institute for Wine Biotechnology at Stellenbosch University on the biopreservation in wine. Our results indicated that possible antimicrobial compounds of proteinaceous nature, produced by AAB isolated from wine, do exist. It was found that two different species of AAB, namely Acetobacter aeeti and Gluconobacter frateurii, produced antimicrobial compounds that inhibited other species of AAB. Preliminary results indicated that these compounds are heat sensitive and stable in a wide pH range. It was also shown that after the action of proteolytic enzymes, such as proteinase K and a-chemotrypsin, all inhibitory activity was lost. This study also revealed the existence of the species Gluconobacter frateurii, which have not yet been associated with the winemaking environment. This study made a valuable contribution to the limited amount of information and understanding of AAB, not only in the wine environment, but also elsewhere. The results and findings of this research would serve as platform for further projects. This might soon lead to the development of antimicrobial substances or tailored wine-yeasts with antimicrobial abilities, which can be applied during winemaking to assist the winemaker in combatting high cell numbers and subsequent spoilage by AAB. / AFRIKAANSE OPSOMMING: Wynkwaliteit word beïnvloed deur 'n verskeidenheid van mikroorganismes wat regdeur die wynrnaakproses teenwoordig is. Die giste is vir die alkoholiese fermentasie, die melksuurbakterieë (MSB) vir die appelmelksuurgisting, terwyl die asynsuurbakterieë (ASB) vir die omskakeling van etanol na asynsuur verantwoordelik is. AI hierdie mikroorganismes is teenwoordig op die druiwe en in die kelder, en dit dien gevolglik as 'n weg waardeur hulle in die fermentasietenke kan kom om sodoende die wynkwaliteit te beïnvloed. Hierdie mikroorganismes kan egter gesien word as óf voordelig óf as wynbederfmikroorganismes, afhangende van die heersende kondisies gedurende die wynrnaakproses. Dit is daarom baie belangrik om enige proses te voorkom wat tot 'n verlaging in wynkwaliteit kan lei. Wat laasgenoemde aanbetref, is daar sekere faktore wat altyd geëvalueer moet word, naamlik die druifkwaliteit, wynrnaaktegnieke en kwaliteitsbeheer. Een van die maatreëls wat geïmplementeer is om mikrobiologiese stabiliteit tydens die wynrnaakproses te handhaaf, is die gebruik van chemiese preserveermiddels. Swaweidioksied (S02) word algemeen gebruik as primêre preserveermiddel tydens wynrnaak. Daar is egter 'n toenemende verbruikersweerstand teen die gebruik van chemiese preserveermiddels, aangesien dit moontlike gesondheidsrisiko's kan inhou, asook tot 'n verlaging in sensoriese kwaliteit van die wyn kan lei. 'n Alternatiewe benadering vir chemiese preservering, wat reeds tot verskeie nuwe ondersoeke gelei het, is biologiese preservering of biopreservering. Dit is die gebruik van die natuurlike mikroflora en/of hulle antimikrobiese produkte, soos bv. bakteriosiene, om die sensitiewe mikroorganismes wat in dieselfe omgewing voorkom, se groei te inhibeer óf om hulle dood te maak. Aanduidings vanuit die wynbedryf dui daarop dat bakteriese bederf steeds 'n algemene probleem is wat in baie kelders ondervind word. Hierdie bakteriese bederf kan onder andere twee hoofprobleme veroorsaak, wat 'n groot bekommernis vir verskeie wynmakers is. Dié probleme sluit in hoë vlakke van vlugtige suurheid, wat gevolglik die wyn 'n asyn-afgeur gee, en slepende/gestaakte fermentasies, wat die gevolg is van komponente soos asynsuur en ander vetsure, wat die gis se groei inhibeer. Die feit dat asynsuur die gemeenskaplike faktor in beide gevalle was, het daarop gedui dat 'n ondersoek rakende die hoofproduseerder van asynsuur, naamlik ASB, benodig word. ASB word gevolglik as een van die hoofbederforganismes wat met die wynrnaakproses geassosieer word, beskou. Die meeste navorsing oor biopreservering in die voedsel -en drank bedryf is op die Gram-positiewe MSB gedoen. Die spektrum van inhibisie van die bakteriosiene van MSB sluit egter die meeste Gram-negatiewe bakterieë uit, veral ASB, en dit dui daarop dat ASB gesif moet word in 'n soektog na antimikrobiese substanse wat moontlik gebruik kan word om hul getalle tydens die wynrnaakproses te beheer. Geen bewyse kon tot dusver uit die literatuur gekry word met betrekking tot antimikrobiese aktiwiteit teen ASB nie, daarom word hierdie navorsing dus as nuut beskou. Hierdie studie se hoofdoelwittewas om die wyn-isolate van ASB vir die produksie van antimikrobiese peptiede te sif. Dit is gevolg deur die isolasie en voorlopige karakterisering van die geproduseerde antimikrobiese komponente. Daar is ook verskeie pogings aangewend om die produksie van die antimikrobiese substanse, asook die isolasieprosedures, te optimiseer. Hierdie studie vorm deel van 'n groter navorsingsprogram oor biopreservering van wyn wat deur die Instituut vir Wynbiotegnologie by die Universiteit van Stellenbosch geïnisieer is. Die resultate het daarop gedui dat antimikrobiese substanse van proteïenagtige aard, afkomstig vanaf wyn-isolate van ASB, wel bestaan. Daar is gevind dat twee veskillende spesies, naamlik Aeefobaefer aeefi en Glueonobaefer frafeurii, antimikrobiese peptiede produseer, wat ander spesies van ASB kan inhibeer. Voorlopige resultate het getoon dat hierdie substanse hitte-sensitief is en ook stabiel is oor 'n wye pH-reeks. Daar was ook aanduidings dat, ná die aksie van proteolitiese ensieme, soos bv. proteïnase K en a-chemotripsien, al die inhibitoriese aktiwiteit verlore gegaan het. Hierdie studie het ook die voorkoms van die spesies Glueonobaefer frafeurii aangedui, wat nog nie tot dusver met die wynrnaakomgewing geassosieer is nie. Hierdie studie maak 'n waardevolle bydrae tot die beperkte hoeveelheid inligting oor en begrip van ASB, nie net in die wynomgewing nie, maar ook in die algemeen in die natuur. Die bevindinge en resultate van hierdie navorsing sal as basis dien vir verdere projekte wat sal volg. Dit kan moontlik binnekort lei tot die ontwikkeling van antimikrobiese substanse, en ook pasgemaakte wyngiste met antimikrobiese vermoëns, wat tydens die wynrnaakproses gebruik kan word om sodoende die wynmaker in staat te stelom die hoë bakteriese getalle en die gevolglike bederf deur ASB, te beheer.

Dissertation (PhD)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Wine is the product of a complex biological and biochemical interaction between grapes and different microorganisms (fungi, yeasts, lactic acid bacteria and acetic acid bacteria, as well as the mycoviruses and bacteriophages affecting them) in which yeasts play the most important role regarding the alcoholic (primary) fermentation. These wine-associated yeasts can be divided into Saccharomyces and non-Saccharomyces yeasts. During fermentation, there is a sequence of dominance by the various non-Saccharomyces yeasts, followed by Saccharomyces cerevisiae, which then completes the fermentation. This is especially evident in spontaneously fermenting must, which has a low initial S. cerevisiae concentration. Some non- Saccharomyces yeasts can also be found throughout the fermentation. The non- Saccharomyces presence in the fermentation can affect wine quality, either positively or negatively. A positive contribution could be especially useful to improve wines produced from grape varieties with a neutral flavour profile due to non-optimal climatic conditions and/or soil types. As part of a comprehensive South African research programme, the specific objectives of this study were: the isolation of indigenous non-Saccharomyces yeasts from vineyards and musts; the identification of these isolates; the characterisation and evaluation of predominant species under winemaking conditions; and the development of a protocol for their use in enhancing wine quality. Initially, 720 isolates representing 24 different species, were isolated from grape (vineyard) and must samples taken over three vintages from four distinctly different wine producing regions. The isolates were characterised and grouped utilising biochemical profiles and DNA karyotyping, whereupon representative isolates were identified. The yeast species that had the highest incidence of predominance in the vineyard was Kloeckera apiculafa. However, some vineyard samples were characterised by low numbers or absence of this yeast, which is not according to generally accepted norms. Other species that also predominated in a few of the vineyard samples were Candida pulcherrima, Kluyveromyces thermofolerans, Rhodotorula sp. and Zygosaccharomyces bailii. Generally, there was a greater diversity of yeasts in the processed must than from the vineyard samples. Furthermore, while each sample showed a different yeast population, no pattern linking species to climatic zone was observed. Four species i.e. Candida collieulosa, Candida pulcherrima, Candida stel/ata and Kloeckera apiculata, were found to predominate in grape must samples. Representative strains consequently received further attention during laboratory and small-scale winemaking trials. A protocol was developed whereby individual species could be used in co-inoculated fermentations with S. cerevisiae in the small-scale production of wine. An improvement in wine quality was achieved and it was found that there was a link between specific species and grape cultivar. The ability of C. pulcherrima to improve Chenin blanc wine quality was investigated further. Results over three vintages showed that the wine produced by the co-inoculated fermentation was superior to that of a reference wine (produced by S. cerevisiae only). The improvement in wine quality was not linked to increased ester content nor were the standard chemical analyses adversely affected. The effects of pH and wine production parameters i.e. 802, fermentation temperature and use of di-ammonium phosphate (DAP), on this yeast followed the same pattern as that known for S. cerevisiae. This study was successfully completed and the developed protocol can be used for the improvement of Chenin blanc wine where additional aroma and quality is needed. / AFRIKAANSE OPSOMMING: Wyn is die produk van 'n komplekse biologiese en biochemiese interaksie tussen druiwe en mikroorganismes (swamme, giste, melksuurbakterieë, asynsuurbakterieë, asook die mikovirusse en bakteriofage wat hul beïnvloed) waar gis die belangrikste rol speel ten opsigte van die alkoholiese (primêre) fermentasie. Die betrokke giste kan in Saccharomyces- en nie-Saccharomyces-giste verdeel word. Tydens gisting vind daar 'n opeenvolging van dominansie deur die verskillende nie-Saccharomyces giste plaas, gevolg deur Saccharomyces cerevisiae, wat dan die gisting voltooi. Dit is veral in spontaan fermenterende mos, waarin aanvanklik lae konsentrasies S. cerevisiae-gisselle voorkom, waarneembaar. Sekere nie-Saccharomyces-giste kan ook regdeur die verloop van fermentasie gevind word. Die teenwoordigheid van nie-Saccharomyces-giste kan 'n bydrae maak tot wynkwaliteit, hetsy positief of negatief. 'n Positiewe bydrae kan veral nuttig wees vir die verbetering van wyn geproduseer van druifsoorte met neutrale geurprofiele as gevolg van nie-optimale klimaatstoestande en/of grondtipes. As deel van 'n uitgebreide Suid-Afrikaanse navorsingsprogram, was die doelwitte van hierdie studie soos volg: die isolasie van inheemse nie-Saccharomyces-giste vanuit wingerde en mos; die identifikasie van hierdie isolate; die karakterisering en evaluering van spesies wat tydens wynbereiding oorheers; en die ontwikkeling van 'n protokol waarin geselekteerde nie- Saccharomyces-giste gebruik kan word vir die verbetering van wynkwaliteit. Druif- en mosmonsters is oor drie oestye vanuit vier duidelik onderskeibare wynproduserende gebiede geneem en 720 isolate, verteenwoordigend van 24 verskillende spesies, is hieruit geïsoleer. Hierdie isolate is volgens biochemiese profiele en DNA-kariotipering gekarakteriseer en gegroepeer waarna verteenwoordigende isolate geïdentifiseer is. Die gisspesie wat die meeste in wingerde voorgekom het, was Kloeckera apiculata. Sommige wingerde is egter deur lae getalle of afwesigheid van dié gis gekenmerk, In feit wat afwyk van die algemeen aanvaarde norm. Ander spesies, nl. Candida pulcherrima, Kluyveromyces thermotolerans, Rhodotorula sp. en Zygosaccharomyces bailii, het ook in enkele gevalle in die wingerdmonsters oorheers. Oor die algemeen was daar 'n groter diversiteit van giste in die geprosesseerde mos as in die wingerdmonsters. Verder is elke monster gekenmerk deur verskillende gispopulasies, maar geen verband tussen gisspesie en klimaatsone is waargeneem nie. Vier spesies, nl. Candida collieulosa, Candida pulcherrima, Candida stel/ata en Kloeckera apiculata, het in hoë getalle in die druiwemosmonsters oorheers en verteenwoordigende rasse het verdere aandag tydens laboratorium- en kleinskaalse wynmaakproewe geniet. 'n Protokol, waar hierdie rasse individueel gebruik is in gesamentlike geïnokuleerde fermentasies met S. cerevisiae vir die kleinskaalse produksie van wyn, is ontwikkel. 'n Verbetering in wynkwaliteit is verkry en daar is 'n verband tussen spesifieke gisspesies en druifvariëteit gevind. Gevolglik is die vermoë van C. pulcherrima om die gehalte van Chenin blanc wyn te verbeter, verder ondersoek. Resultate oor drie oesjare het gewys dat die wyn wat met die C. pulcherrima / S. cerevisiae kombinasie geproduseer is, beter was as 'n verwysingswyn (deur slegs S. cerevisiae geproduseer). Die waargenome verbetering in wynkwaliteit was egter nie aan 'n verhoging in esterinhoud te danke nie en die standaard chemiese analises het geen negatiewe afwyking uitgewys nie. Verder is gevind dat die effek van pH en wynproduksieparameters, nl. die gebruik van S02, fermentasietemperatuur en die gebruik van di-ammoniumfosfaat (DAP), dieselfde patroon as die bekend vir S. cerevisiae gevolg het. Die ontwikkelde protokol kan nou aangewend word waar verhoogde Chen in blanc wynaroma en kwaliteit verlang word.

published_or_final_version / Business Administration / Master / Master of Business Administration

The passing of the 21st Amendment to the United States Constitution has given to individual states the authority to regulate the sale, distribution and taxation of domestically produced wines, and made the wine trade potentially significant as a means of augmenting state revenues. In the state of Oregon, table wines have been taxed at the rate of 23 cents per gallon irrespective of origin. The objective of this study has been to evaluate the nature and price elasticity of Oregon's wholesale demand for California table wines with a view to determine the effectiveness of the utilization of the tax. The multiple regression analysis technique is the instrument used in this determination. A two part statistical model was employed, but the number of variables used had to be restricted because of certain data limitations. Only 78 percent and 50 percent of variation was explained in the price predicting and demand segments of the model respectively. The results of the statistical analysis indicated a positively sloped demand curve. This rendered any application of the concept of price elasticity of demand as a means of assessing how effective the tax was being used meaningless. In view of this, no recommendations have been made, but the need for further research as more data become available has been pointed out. / Graduation date: 1971

The purposeful induction of malolactic fermentation (MLF) in wines such as Pinot Noir and Chardonnay is an established commercial wine making practice in Oregon. This induction is not always successful, especially with white wines, such as Chardonnay. A study was initiated to examine the compatibility of yeasts commonly used in Oregon winemaking with various strains of malolactic bacteria. In preliminary and pilot plant scale experiments, the yeast strain found to be most conducive to malolactic fermentation by lactic acid bacteria was Montrachet (Red Star). The malolactic bacterial strains that were best able to complete malolactic fermentation in various wines, fermented by different yeast strains, were the two Oregon commercial strains, ER1A and Ey2d, and the Pinot Noir juice isolate, DAPN85A. Sensory analysis of aroma by difference from control test was done on Chardonnay wine fermented by 4 different yeast strains and 3 different malolactic bacterial strains. In all cases, there was an overall significant difference in malolactic fermented wine aroma when compared to control wines. Organic acid analyses by high pressure liquid chromatography (HPLC) and analyses of volatile compounds by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were done on selected Chardonnay wines. Propionic acid was found to diminish in malolactic fermented wines while acetic acid content increased. Isobutanol and isobutyraldehyde increased significantly in MLF wines, compared to the controls. Chemical analyses of MLF and control wines suggested two possible chemical reactions resulting from the MLF. The first was the reduction of isobutyraldehyde to isobutanol, and the second was the hydrolysis of isobutyl acetate to isobutyraldehyde and acetate. On all GC chromatograms of wines, where MLF had occurred, there was an unidentified peak close to the retention time of isoamyl acetate. This peak was not evident in wines where MLF had not occurred. Eight compounds were tentatively identified by GC-MS in malolactic fermented wines which were not found in the control wines. These were 4-methyl-3-pentanoic acid, methyl acetate, ethyl hexanoate, hexyl acetate, 1,12-tridecadiene, hexadecanoic acid, and a compound which was tentatively identified as farnesol, or 1,2-benzenedicarboxylic acid. The latter four compounds had identity fits of less than 900 from the mass spectral analysis. Whether any of these eight compounds match the unknown "ML peak" found in the GC chromatograms is unknown. / Graduation date: 1989

This thesis is the first to study the history of champagne in nineteenth-century Britain, a period in which the usage and style of champagne changed fundamentally. From a sweet, lightly effervescent wine drunk on its own or with desserts, it became a fully dry and fully sparkling wine drunk throughout the meal. The central questions I address are why these changes occurred and what role the marketing and branding of champagne played in these changes. This analysis integrates production studies (including marketing and branding) and consumption studies by drawing on the rich vein of contemporary consumption data and the evidence of the day-to-day practice of the London agents of the French champagne houses. The thesis demonstrates that champagne was able to develop uniquely powerful brands that were managed in ways that closely prefigure the marketing practice of modern luxury brand owners. Historiography: Whilst there have been many books on the subject of consumption in the last three decades, very few of these have focused on drinkers and drinking. There have also been many different approaches to consumption studies from sociologists, anthropologists, literary scholars and historians and this work draws on all those traditions. My own interest lies in the changing daily habits of consumption and I have therefore drawn extensively not just on the historical scholarship but also on the writings of modern experts on branding and marketing to understand how consumer choice is currently understood and managed. The commercial importance of food and drink means much work has been done in these areas - not excluding wine. The history of drink in the last three centuries, however, has had relatively little interest until recently. Recent works by John Burnett, Charles Ludington and James Simpson illuminate the general history of wine in Britain but, though there are many general books on champagne, there has only been one history, that published by André Simon in 1905. Simon, agent for a champagne producer, was well placed to understand the trade and his work remains an important source. I have endeavoured to review all these works through the lens of the nineteenth-century British press and the archives of selected champagne producers and their British distributors.

Includes a list of publications co-authored by the author during the preparation of this thesis. Bibliography: leaves 103-111. Studies the links between grape composition, wine composition and wine sensory properties. Developed a new method of measuring glycoside concentration in grapes (glycosyl-glucose assay) and a modified measurement of wine colour density in red wine. These were used to analyse samples of Shiraz grapes and wines from a comprehensive vineyard irrigation trial. Glycosyl-glucose concentrations shows promise for the prediction of wine composition and flavor intensity.

Bibliography: p. 227-253. / xvii, 254 p. : ill. (chiefly col.), photos (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This project sought to examine the spatial and temporal distribution, as well as the composition, of the flavan-3-ols, proanthocyanidins and flavonols in winegrapes throughout berry development. In addition, the author sought to explore how modifying bunch exposure to light would impact upon flavonoid biosynthesis in the grape berry by comparing the flavonoid composition of shaded and exposed grapes. The expression of key genes in the flavonoid biosynthetic pathway was also investigated to understand how the pathway is regulated during berry development. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Wine and Horticulture, 2004

Bibliography: leaves 195-209. / xxvi, 209 leaves : ill., ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study investigated seed development, phenolic composition of seeds and skins, and phenolic composition and sensory properties of wines made from berries of Vitis Vinifera L. cv. Shiraz that were developed and ripened under different levels of sunlight intensity at the bunch zone. The study also examined the relationships between seed and berry development, and the links between berry composition, wine composition and wine sensory properties. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Wine and Horticulture, 2004

Bibliography: leaves 200-214. / xi, 214 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Three structurally related compounds, 2-acetyltetrahydropyridine (ACTPY), 2-ethyltetrahydropyridine (ETPY) and N-heterocycle, 2-acetyl-1-pyrroline (ACPY), were quantified and found to be unique components of mousy wines. 35 lactic acid bacteria (LAB) were screened for the ability to produce mousy off-flavour. In addition to Lactobacillus brevis and L. cellobiosus, a diversity of LAB species, particularly heterofermentative Lactobacillus spp. and Oenococcus oeni exhibited this ability in a range of ethanolic and wine-based media. The substrates and metabolism of mousy compound formation by LAB were also investigated. A pathway for the formation of ACPY and ACTPY by heterofermentative LAB was proposed. / Thesis (Ph.D.)--University of Adelaide, Dept. of Horticulture, Viticulture & Oenology, 1999