Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Lactic acid bacteria (LAB) play a vital role in reducing wine acidity and also contributing to its aroma and flavour. However, they can also be responsible for many wine spoilage problems that compromise the quality and value of wine. While Oenococcus oeni contributes positive characteristics to the sensory properties of wine, certain species of the genera, Lactobacillus and Pediococcus can affect the wholesomeness of wine by producing undesirable compounds, such as biogenic amines and ethyl carbamate. Chemical preservatives like sulphur dioxide (SO2) are used to prevent the growth of spoilage micro-organisms during the winemaking process. SO2 also acts as a reducing agent and maintains the benefits of antioxidant properties of the polyphenols of wine. However, there is a worldwide demand to reduce SO2 levels due to the increasing health related risks and other factors. All these considerations have increased the interest in research to look for new preservation strategies, and LAB-produced bacteriocins seem to be a potential alternative that has been explored in the last decade. Various types of bacteriocins have been identified and characterized. However, there are few reports on bacteriocins produced by LAB of oenological origin or on bacteriocins present in the finished wine. The present study screened 155 LAB isolates from the IWBT culture collection for bacteriocin production. The isolates originated from South African red wines undergoing spontenous malolactic fermentation (MLF). Eight strains (5%) were identified to be producers, as evidenced by strong inhibition zones formed against sensitive organisms on agar plates. The producers demonstrated a broad spectrum of antimicrobial activity by inhibiting Lactobacillus spp., Leuconostoc mesenteroides, Listeria monocytogenes and Pediococcus pentosaceus strains. Some of these bacterial genera are important in winemaking since they are potential wine spoilage bacteria. Hence these strains and/or the bacteriocins they produce could possibly find application in the food fermentation industry. The physiological results, biochemical tests and sugar fermentation profiles all gave the same results for the seven isolates, which were indicative of enterococci. The identification through 16S rRNA gene sequencing revealed that the seven tested isolates were all Enterococccus faecium. RAPD-PCR fingerprinting gave the same profile for the seven strains confirming that they were all identical on genetic level. Determining the molecular weight using SDS-PAGE showed the peptides to be below 4.6 kDa in size. PCR amplification of the enterocin P gene, sequencing and BLAST search results confirmed that all eight strains contained the enterocin P gene from Ent. faecium. The enterocin tested in this study was heat stable at 100°C (30 min), but lost 50% of its activity at 121°C (15 min). Factors such as bacteriocin production and heat resistance are among many that enable enterococci to be dominant in fermented products such as dairy foods or meat. Therefore, enterococci producing bacteriocins have potential applications in various foods and fermented products. The pH tests showed enterocin to be active over a broad pH range (2-10). Enterocin activity over a wide pH range make them potentially more suitable as natural preservatives of foods and fermented products where products are acidified or pH decreases due to natural LAB present. They also have potential applications in oenological process where pH levels are as low as 3 and 4. Proteolytic enzyme treatments with lysozyme, lipase, lyticase and catalase could not inhibit enterocin activity. This indicated that their antimicrobial activity was independent of lipid or carbohydrate moieties or hydrogen peroxide. α-Chymotrypsin and proteinase K inactivated enterocin, which indicated that the compound was proteinaceous in nature. Bacteriocin production tested in two of the isolates, #16.3 and 128.1, coincided with the exponential growth phase which occurred after 6 hours of incubation at 30°C, which was an indication of primary metabolite kinetics. The highest production of 400 AU/ml was observed after eight hours and was maintained for several hours (46 hours) in the stationery phase. The bactericidal effect of the cell free supernatants from #16.3 and 128.1 against the sensitive culture of Lactobacillus pentosus DSM 20314 was clearly demonstrated by complete inhibition of growth for most of the experimental period, while the control increased exponentially throughout the experiment. In conclusion, this study has confirmed the isolation and identification of Ent. faecium strains from wine, a genus that is rarely found in the wine environment. Although one can speculate on the origin of this bacterium in the wine e.g. human handling and contaminated water, these bacterial isolates produced enterocin P which have antimicrobial action against wine-related LAB genera and therefore have a potential role in wine spoilage control. / AFRIKAANSE OPSOMMING: Melksuurbakterieë (MSB) speel ‘n belangrike rol in die redusering van die suurgehalte van wyn en dra ook by tot die aroma en smaak daarvan. Hulle kan egter ook verantwoordelik wees vir vele wynbederfprobleme wat die gehalte en waarde van wyn negatief beïnvloed. Hoewel Oenococcus oeni positiewe karaktertrekke aan die sensoriese eienskappe van wyn verleen, kan sekere spesies van die genus, Lactobacillus en Pediococcus, die heilsaamheid van wyn beïnvloed deur ongewenste verbindings, soos biogeniese amienes en etielkarbamaat, te produseer. Chemiese preserveermiddels, soos swaweldioksied (SO₂), word gebruik om die groei van bederfmikro-organismes tydens die wynbereidingsproses te voorkom. SO₂ fungeer ook as ‘n reduseermiddel en onderhou die voordele van die antioksidant eienskappe van die poli-fenole van wyn. Daar is egter ‘n wêreldwye vraag na die redusering van SO₂-vlakke as gevolg van die toename in gesondheidsverwante risiko’s en ander faktore. Al hierdie oorwegings het belangstelling in die navorsing van nuwe preserveringstrategieë laat toeneem en MSB-geproduseerde bakteriosiene lyk na ‘n potensiële alternatief wat in die laaste dekade ondersoek word. Verskeie tipes bakteriosiene is geïdentifiseer en getipeer. Daar is egter nog weinig gerapporteer oor bakteriosiene wat deur MSB van wynkundige oorsprong geproduseer is of oor bakteriosiene wat in afgeronde wyn teenwoordig is. Die huidige studie het 155 MSB isolate van die Instituut vir Wynbiotegnologie se kultuurversameling vir bakteriosien-produsering gegradeer. Agt stamme (5%) is as produseerders geïdentifiseer, soos gestaaf is deur sterk inhibisiesones wat teen sensitiewe organismes op agarplate gevorm het. Die produseerders het ‘n breë spektrum van antimikrobiese aktiwiteit by inhiberende Lactobacillus spp., Leuconostoc mesenteroides, Listeria monocytogenes en Pediococcus pentosaceus stamme gedemonstreer. Sommige van hierdie bakteriese genera is belangrik in wynbereiding, omdat dit potensiële wynbederfbakterieë is. Hierdie isolate en/of die bakteriosiene wat dit produseer, kan dus moontlik toepassing in die voedselfermentasiebedryf vind. Die fisiologiese resultate, biochemiese toetse en suikerfermentasieprofiele het almal dieselfde resultate vir die sewe isolate, wat indikatief van enterococci was, gelewer. Die identifisering deur 16S rRNA-basispaaropeenvolging het onthul dat die sewe getoetste isolate almal Enterococccus faecium was. RAPD-PKR-vingerafdrukke het dieselfde profiel vir die sewe rasse gelewer, wat bevestig dat die rasse almal identies op genetiese vlak was. Deur die molekulêre gewig vas te stel deur middel van SDSPAGE, het dit getoon dat die peptiede kleiner as 4.6 kDa in grootte is. PKR-amplifikasie van die enterosien-P geen, die bepaling van basispaaropeenvolging en BLAST-soekresultate het bevestig dat al agt rasse die enterosien-Pgeen van Ent. faecium bevat. Die enterosien wat in hierdie studie getoets is, was hitte-stabiel teen 100°C (30 min), maar het 50% van sy aktiwiteit teen 121°C (15 min) verloor. Faktore soos bakteriosienproduksie en hittebestandheid, is van die vele faktore wat enterococci in staat stel om dominant in gefermenteerde produkte, soos suiwelprodukte of vleis te wees. Enterococci wat bakteriosiene produseer het dus potensiële toepassings in verskeie kossoorte en gefermenteerde produkte. Die pH-toetse het getoon dat enterosien-P oor ‘n breë pH spektrum (2-10) aktief was. Enterosienaktiwiteit oor ‘n wye pH spektrum maak dit potensieel meer geskik as natuurlike preserveermiddels vir kossoorte en gefermenteerde produkte waar produkte versuur word of die pH afneem as gevolg van natuurlike MSB wat teenwoordig is. Dit het ook potensiële toepassings in enologiese prosessering waar pH-vlakke so laag as 3 en 4 is. Proteolitiese ensiembehandelings met lisosiem, lipase, litikase en katalase kon nie enterosienaktiwiteit inhibeer nie. Daar is getoon dat hul antimikrobiese aktiwiteit onafhanklik was van lipiede, koolhidraatdele óf waterstofperoksied. α-Chymotripsien en proteïenase-K het enterosien onaktief gemaak, wat getoon het dat die samestelling proteïenagtig van nature is. Bakteriosienproduksie wat in twee van die stamme #16.3 en 128.1 getoets is, het ooreengestem met die eksponensiële groeifase wat na 6 ure van inkubasie teen 30°C plaasgevind het, en wat ‘n aanduiding is van primêre metabolitiese kinetika. Die hoogste produksie van 400 AU/ml is na agt ure waargeneem en is vir etlike ure (46 uur) in die stasionêre fase gehandhaaf. Die bakterie-dodende effek van die selvrye supernatant van #16.3 en 128.1 teenoor die sensitiewe kultuur van Lactobacillus pentosus DSM 20314 is duidelik gedemonstreer deur totale inhibisie van groei vir die grootste deel van die eksperimentele periode, terwyl die kontrole eksponensieel deur die hele eksperiment toegeneem het. Hierdie studie het dus die isolering en identifisering van Ent. faecium-stamme, ‘n genus wat baie selde gevind word in ‘n wynomgewing, vanuit wyn bevestig. Alhoewel daar gespekuleer kan word oor die oorsprong van hierdie bakterie in wyn bv. menslike hantering en besmette water, het hierdie rasse wel enterosien geproduseer en daarom die potensiaal om ‘n rol te speel in beheer teen verskeie bederf-MSB-genera. / TIA, NRF and THRIP

Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The relationships between leaf and fruit represent a fundamental concept in perennial plants. This concept allows to understand and to manage, with regard to farming, the balance of a vine, which is important in terms of fruit quality (i.e. fruit composition), mainly when it comes to producing wines of different categories and styles. The understanding of vine structure, physiology and vine functioning ultimately allows for appropriate recommendations to be given with regard to farming procedures. These include the adaptation of the canopy architecture to achieve a certain yield per vine, the determination of an appropriate fruit microclimate as well as the prediction of harvest dates. One of the central notions of vine balance involves the relationship between the source and the sink organs. The definition of source-sink relationships incorporates several concepts, including the ability of a source tissue to produce carbohydrates through photosynthesis, the transport of these carbohydrates to various plant organs-tissues via appropriate transport channels, and the assimilation and storage of the carbohydrates in the sink organs. In past years, a number of simple ratios have been created to incorporate the relationship between source and sink organs and thereby define vine balance in order to aid in practical management decisions (choice of a training system, irrigation, canopy manipulation etc.). However, vine functioning is very complex and cannot be defined accurately by simple, static ratios. More integrated and dynamic physiological indicators of vine balance and functioning are needed in order to understand the complex communication between organs and ultimately improve on farming practices. In order to achieve this, a better grasp of source-sink relationships, including the signalisation between organs and the functioning of the transport tissues is required. A two year experiment was proposed to study the interaction between source and sink organs using a combination of both primary shoot girdling methods and berry classification according to size. Girdling removes the bark and phloem tissue, thereby interrupting carbon import as well as water flow to the bunch to a certain degree. The aim of the study was to demonstrate the complexity of vine functioning by investigating the dynamics of berry sugar and water accumulation (used as physiological indicators) and the influence thereof on berry fresh mass evolution. Furthermore, the use of berry sugar loading was proposed as an improved physiological indicator of vine balance as it is directly linked to source and sink functioning. Sugar production and the dynamics of berry sugar accumulation rely on photosynthesis which in turn is dependent on stomatal conductance and therefore also incorporates the effects of external abiotic factors (temperature, light and water). It furthermore gives a direct indication of sink functioning as it shows the progressive accumulation of sugar throughout the ripening period and the possible consequences on berry volume evolution. A primary shoot which bore two bunches was used to represent a biological replicate. The lower bunches were girdled above and below in order to completely isolate them from any carbohydrate import. These bunches, along with the upper ungirdled bunches and two control bunches from another shoot were sampled. The berries from these bunches were classified according to diameter, thereby providing the unique opportunity to study berries of the same volume/size. Measurements were done to determine the fresh and dry masses of the sampled berries, as well as to analyse the concomitant sugar concentrations. It was found that girdling clearly had an effect on berry sugar dynamics and the method was improved in the second year of the trial. Girdling in interaction with berry classification according to diameter demonstrated that berries from the same size could have different sugar concentrations. It further showed that, to a certain degree, a relationship exists between the first rapid phase of sugar accumulation and the post véraison increase in berry fresh mass, until the plateau of fruit sugar accumulation, which generally occurs around a sugar concentration of 20 Brix. Additionally, and more importantly, it was found that vine functioning and the balance between the source and the sink organs may be controlled to a certain degree. There is a strong degree of compensation within a vine which results from signalling between and within organs. When taking the results of this study into consideration, it becomes clear that the classical ratios used to quantify the complex relationships between the fruit and the leaves may not be completely adequate to do so. The current way of looking at source-sink relationships and thereby determining whether a vine is balanced or not is over-simplified and there are numerous limitations involved in this approach. The vine is far more complex and various aspects must be taken into consideration before any claims can be made concerning source-sink relationships and consequently leaf to fruit balance. / AFRIKAANSE OPSOMMING: Die verhoudings tussen blaar en vrug verteenwoordig ‘n fundamentele konsep in meerjarige plante. Begrip van hierdie konsep maak dit moontlik om in boerdery die balans van ‘n wingerdstok te verstaan en bestuur. Hierdie wingerdbalans is belangrik in terme van vrugkwaliteit (d.w.s. vrugsamestelling), hoofsaaklik met betrekking tot die produksie van wyne van verskillende kategorieë en style. Begrip van die wingerdstok se struktuur, fisiologie en funksionering maak dit moontlik om gepaste aanbevelings te maak rakende boerdery prosedures. Dit sluit in die aanpassing van die lower argitektuur om ‘n sekere opbrengs per wingerdstok te verkry, die vasstel van ‘n geskikte vrug mikroklimaat asook die voorspelling van oesdatums. Een van die sentrale denkwyses rondom wingerdstok funksionering behels die die bron-vragpunt verhouding. Die definisie van bron-vragpunt verhoudings inkorporeer verskeie konsepte, insluitende die vermoë van ‘n bronweefsel om koolhidrate te produseer deur fotosintese, die vervoer van hierdie koolhidrate na verskeie plantorgaan weefsels via die gepaste vervoerkanale asook die opname en berging van hierdie koolhidrate in die vragpunt organe. In die verlede is ‘n aantal eenvoudige verhoudings geskep om die verband tussen die bron en vragpunt organe te beskryf en sodoende die wingerdstokbalans te definieer met die doel om ondersteuning te bied in praktiese bestuursbesluite (die keuse van opleistelsel, besproeiing, lowermanipulasie, ens.). Wingerdstok funksionering is egter baie kompleks en kan nie akkuraat gedefinieer word deur eenvoudige, statiese verhoudings nie. Meer geïntegreerde en dinamiese fisiologiese aanwysers van wingerdstokbalans en funksionering is nodig om die komplekse kommunikasie tussen organe te verstaan en uiteindelik boerdery praktyke te verbeter. Om dit te bereik is ‘n beter begrip van bron-vragpunt verhoudings asook die seinoordrag tussen organe en die werking van die vervoerweefsels nodig. ‘n Twee jaar lange eksperiment is voorgestel om die interaksie tussen bron- en benuttingsorgane te ondersoek deur gebruik te maak van beide die primêre loot ringelering metode en korrel klassifikasie volgens grootte. Ringelering verwyder die bas en floëem weefsel en onderbreek sodoende koolstof invoer sowel as watertoevoer na die tros tot ‘n sekere mate. Die doel van die studie was om die kompleksiteit van wingerdstok funksionering aan te toon deur die dinamika van suiker en water akkumulasie in die korrel te ondersoek asook die invloed daarvan op korrel vars massa ontwikkeling. Verder is die gebruik van korrel suikerlading voorgestel as ‘n beter fisiologiese aanduiding van wingerdstok funksionering aangesien dit direk geassosieer is met bron-vragpunt funksionering. Suikerproduksie en die dinamika van suiker akkumulasie in die korrel berus op fotosintese wat weer afhanklik is van stomatale geleiding en daarom ook die effek van eksterne abiotiese faktore (temperatuur, lig en water) inkorporeer. Dit gee verder ‘n direkte aanduiding van die funksionering van die vragpunt organe omdat dit die progressiewe akkumulasie van suiker gedurende die rypwordingsperiode aantoon, asook die moontlike gevolge op korrelvolume ontwikkeling. ‘n Primêre loot wat twee trosse dra is gebruik om ‘n biologiese herhaling te verteenwoordig. Die laer trosse is bo en onder geringeleer om hulle heeltemal te isoleer van enige koolhidraat invoer. Hierdie trosse, tesame met boonste ongeringeleerde trosse en twee kontrole trosse vanaf ‘n ander loot is gemonster. Die korrels van hierdie trosse is geklassifiseer volgens hulle deursnee, om sodoende die unieke moontlikheid daar te stel om korrels van dieselfde volume/ grootte te bestudeer. Metings is gedoen om die vars en droë massas van die gemonsterde korrels te bepaal, asook om die gepaardgaande suikerkonsentrasies te analiseer. Daar is gevind dat ringelering duidelik ‘n effek gehad het op korrelsuiker dinamika en die metode is verbeter in die tweede jaar van die proef. Ringelering in wisselwerking met korrel klassifikasie volgens korrel deursnee het aangetoon dat korrels met dieselfde grootte verskillende suikerkonsentrasies kon hê. Dit het verder aangedui dat daar, tot ‘n sekere mate, ‘n verhouding bestaan tussen die vinnige fase van suiker akkumulasie en die na-véraison toename in korrel vars massa, totdat die plato in suiker akkumulasie bereik word, gewoonlik rondom ‘n suikerkonsentrasie van 20 Brix. Daarbenewens, en van groter belang, is gevind dat wingerdstok funksionering en die balans tussen die bron en vragpunt organe onder ‘n mate van beheer is. Daar is ‘n sterk mate van kompensasie binne ‘n wingerdstok wat die gevolg is van seinoordrag tussen en binne organe in die wingerdstok. Wanneer die resultate van hierdie studie in aanmerking geneem word, word dit duidelik dat die klassieke verhoudings, wat gebruik word om wingerdstok funksionering en balans mee te bepaal, moontlik nie beduidend betekenisvol is nie. Die wyse waarop bron-vragpunt verhoudings tans beskou word is, tot ‘n mate, ‘n oorvereenvoudiging en daar is heelwat beperkinge betrokke by hierdie benadering. Die wingerd is baie meer kompleks en verskeie aspekte moet in aanmerking geneem word voordat enige bewering gemaak kan word rakende bron-vragpunt verhoudings. / The University of Stellenbosch and Winetech for financial support

Thesis (MSc (Wine Biotechnology))--University of Stellenbosch, 2006. / The production of premium quality wine is dependant on excellent management of the total wine production value chain. To achieve this we need rapid and reliable analytical tools. Over the last decade Fourier transform infrared (FT-IR) spectroscopy has made a significant contribution to wine research and in the last five years South African institutions have also exploited the use of this technology not only for research, but also in industrial cellars. The FT-IR apparatus is equipped with global calibrations and therefore we first investigated the validity of these for South African conditions. To achieve this new calibration sets for pH, titratable acidity and °Brix were made and compared to the global calibrations with statistical methods. Results obtained between the °Brix calibrations displayed high correlation and the global calibration can therefore be implemented. However, the new TA calibration was more accurate than the global calibration. Results were inconclusive for the new pH calibration sample set and therefore needs to be enlarged before it can be validated as the possibility of being more accurate exists. It was concluded that FT-IR spectroscopy in the simultaneous measurement for °Brix, pH and TA in grape must showed potential for accurate analysis and quality control purposes in an industrial cellar. Rapid analysis of these parameters will lead to higher throughput of grape must samples in the laboratory as well as adhering to good laboratory practices by validation. The importance of correct sample preparation in the laboratory was illustrated when using FT-IR spectroscopy for one-step analysis and adjustments to global calibrations. Results obtained showed that grape parameters such as °Brix, nitrogen content were not influenced by the two sample preparation methods (hand pressed vs. homogenised), but pH, TA, colour index, anthocyanins and polyphenols were influenced. Important key factors were identified in the quality control chain from vineyard to the cellar. Numerous grape loads had an increase in microbial populations after harvesting the vineyard and transport to the weighbridge. Transport is critical especially for the vineyards in the Lutzville area (had the highest yeast population), which are situated the furthest from the cellar. Sauvignon blanc had the highest acetic acid bacteria and lactic acid bacteria populations compared to the other cultivars. Gluconic acid, glycerol and arabitol was highly correlated to each other. High populations of acetic acid bacteria and lactic acid bacteria also had high levels of gluconic acid and 2,3-butanediol in the grape juice. Meso-inositol differed significantly between the vineyard and weighbridge and it had a high standard deviation compared to the mean value of all the samples between the vineyard and weighbridge. Temperature of grape loads delivered to the cellar ranged from 14 to 36ºC, which had a major impact on the grape quality and the resultant wine. It can be concluded for this study that management of the total value chain is of critical importance to ensure that A-grade grapes results in good quality wine that merits the effort of the grape producer.

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