Academic literature on the topic 'Wine quality, wine making'

The killer strains of Torulaspora delbrueckii can be used to improve the dominance of this yeast during must fermentation. The present work analyzes its usefulness for traditional sparkling wine making. T. delbrueckii killer strain dominated base wine fermentation better than non-killer strains and produced dried wines. The foam ability of T. delbrueckii base wines was very low compared to that of Saccharomyces cerevisiae. Significant positive correlations of foam parameters were found with some amounts of C4–C16 ethyl esters and proteins, and negative correlations with some antifoam alcohols. The organoleptic quality of T. delbrueckii base wines was considered unusual for cava making. While S. cerevisiae (single or mixed with T. delbrueckii) completed the second fermentation to produce dry sparkling wines with high CO2 pressure, single T. delbrueckii did not complete this fermentation, leaving sweet wines with low CO2 pressure. Death due to CO2 pressure was much higher in T. delbrueckii than in S. cerevisiae, making any killer effect of S. cerevisiae on T. delbrueckii irrelevant. However, the organoleptic quality of cava inoculated with mixtures of the two yeast species was better than that of wine inoculated exclusively with S. cerevisiae, and no deterioration in the quality of the foam was observed.

AbstractClimate change will have a profound effect on vine growing worldwide. Wine quality will also be affected, which will raise economic issues. Possible adaptations may result from changes in plant material, viticultural techniques, and the wine-making process. Relocation of vineyards to cooler areas and increased irrigation are other options, but they may result in potential conflicts for land and water use. Grapes are currently grown in many regions around the world, and growers have adapted their practices to the wide range of climatic conditions that can be found among or inside these areas. This knowledge is precious for identifying potential adaptations to climate change. Because climate change affects all activities linked to wine production (grape growing, wine making, wine economics, and environmental issues), multidisciplinary research is needed to guide growers to continue to produce high-quality wines in an economical and environmentally sustainable way. An example of such an interdisciplinary study is the French LACCAVE (long-term adaptation to climate change in viticulture and enology) project, in which researchers from 23 institutes work together on all issues related to the impact of climate change on wine production. (JEL Classifications: Q1, Q5)

Most biochemical reactions involved in the wine-making process are catalyzed by enzymes. The use of enzymes of exogenous origin in wine production is due to the numerous technological and economical advantages demonstrated over time in the winemaking process. Understanding the important role played by enzymes in wine making technology contributes to the development of optimization strategies for the production process to improve the final quality of the wine. In order to accomplish this study, the influence of five oenological preparations with pectolytic and β-glucosidases enzymes types on the volatile compounds of white wines obtained from Fetească regală variety was analyzed by monitoring their evolution during the alcoholic fermentation to the final product. Wine samples have been physically and chemically analysed (pH, acidity, alcoholic strength, density, malic acid, lactic acid, sugar content, SO2, total dry extract and non-reducing extract) according to OIV Standards. Separation and identification of flavor compounds was performed using an Agilent 7890 gas chromatograph coupled to a 5975 C inert XL EI/CI MSD spectrophotometer. The organoleptic evaluation of wines was made according to a wide range of sensory descriptors. An important evolution of volatile compounds during fermentation was observed, depending on the type of enzyme administered, compared to the control sample. Enzymatic treatments did not significantly affect the physico-chemical composition of the wines obtained. The chromatic parameters of the wine samples varied according to the type of enzyme applied. The results of the study showed a significant influence of the enzymes on the organoleptic characteristics of the wines. Therefore, the aromatic quality of a wine is directly proportional to the chemical composition of the grapes and to the technology.

Quality assurance programs (QAPs) may add value to wines through reassuring consumers of wine quality prior to purchase and consumption. In Tennessee, the potential to use a wine QAP is being explored as a means to improve the industry’s economic sustainability. To date, several QAPs exist, but studies directly related to their impact on consumer behavior for wines from emerging areas are scarce. We used an online survey instrument to elicit consumer perceptions of QAPs importance on wine purchasing decisions and how the presence of a QAP may impact their purchasing behavior for a wine from an emerging area (e.g., Tennessee). Wine involvement, QAP perceptions, and familiarity were also measured. A mixed-process model was used to estimate the two ordered probit models for importance of QAPs and the influence of QAPs on Tennessee wine purchases, where QAP importance was treated as a latent variable influencing Tennessee wine purchases. Ordinal probit estimates suggest that greater on-site spending and greater perceived benefits of QAPs (as indicators of quality and standardization) resulted in a higher probability of perceived QAP importance when making wine purchasing decisions. Reduced form estimates of the model of Tennessee wine purchases indicated distance to wine producing areas, female gender, and familiarity with Tennessee wines each negatively influenced the potential impact of QAPs on Tennessee wine purchases. However, on-site spending at wineries and perceived benefits of a Tennessee QAP increased likelihood of Tennessee wine purchases.

Modern development of the Russian viticultural and winemaking industry is aimed at the production of competitive varietal premium wines. It is premised on acceleration of the breeding process of domestic wine grape varieties with the preset course of processing. The purpose of this workск was to study the ratio between the most important quality components of the wines made from two classical and eight promising grape varieties domestic breeding (by Federal State Budget Scientific Institution “North Caucasian Federal Scientific Centre of Horticulture, Viticulture and Winemaking”, hereafter - Institute) to determine the unique varietal particular qualities. The experiment was performed in 2013–2018. The grapes were picked from two plots located in the Central zone and in the Taman subzone, Krasnodar region. The red varietal wines were made according to the same technology and observing the same processing modes. The analytical research was performed repeatedly with qualification assessment of the results. Two-way-ANOVA was used to identify the impact factors upon the wine components. As a result, the following appreciable grape varieties of the Institute’s breeding were isolated, which demonstrated high accumulation of phenolic substances (over 3,000 mg/l) and anthocyanins (700–1100 mg/l) in wine: Vladimir, Granatovy, Kurchansky, Dmitri; the grape varieties with high accumulation of trans-resveratrol in wine: Vladimir (4.7 mg/l), Dmitri (4.7 mg/l), and Kurchansky (3.0 mg/l); the grape varieties for which wine the mass concentration of malic acid was by 2 to 2.5 times higher than the content of tartaric acid: Vladimir and Dmitri. It was shown that Antaris variety has low ecological plasticity and wine of this variety could be differ qualitatively depending upon edaphoclimatic conditions of the subzone.

The changes in and influence of the anti-powdery-mildew fungicides fenarimol and penconazole were studied in the production and quality of rosé wines made with Monastrell grapes grown in the Jumilla wine-producing region in SE Spain. Fungicide concentrations were estimated by gas-liquid chromatography with electron-capture detection. Fermentation was retarded more by penconazole than by fenarimol; in both cases, the slowdown was directly proportional to fungicide concentration. However, the mature wine contained normal concentrations of residual sugars; other enological parameters (pH, volatile acidity, intensity of color and hue) were not significantly affected. Thirty-four days after the start of the experiment, 67% of fenarimol and 52% of penconazole, with respect to the smaller amount initially added (1 mg/liter), were found in the finished wine. The calculated half-life times were 45 and 59 days for penconazole and fenarimol respectively. Different wine-making techniques (racking, clarification, and filtration) had no decisive influence on the removal of fungicide residues from the must, although they eliminated slightly more penconazole than fenarimol.

An alternative methodology is proposed for low temperature winemaking using freeze-dried raw materials. Pine sawdust was delignified and the received porous cellulosic material was applied as immobilization carrier of the psychrotolerant yeast strain Saccharomyces cerevisiae AXAZ-1. The immobilization of yeast cells was examined and verified by scanning electron microscopy (SEM). The immobilized biocatalyst and high-gravity grape must were separately freeze-dried without cryoprotectants and stored at room temperature (20–22 °C) for 3 months. The effect of storage on the fermentation efficiency of the immobilized biocatalyst at low temperatures (1–10 °C), as well as on the aromatic characteristics of the produced wines was evaluated. Storage time had no significant effect on the fermentation efficiency of the biocatalyst resulting in most cases in high ethanol production 13.8–14.8% v/v. The volatile fraction of the produced wines was examined using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography mass spectrometry (GC/MS). GC-MS/SPME analysis along with the organoleptic evaluation revealed in all produced wines a plethora of fresh and fruit aromatic notes. To conclude, fermentation kinetics and aromatic profile evaluation encourages the production of high-quality sweet wines at low temperatures using pine sawdust (Pinus halepensis) entrapped yeast cells as a promoter.

This study aimed to evaluate the usefulness of bioactive extracts obtained from red wine by-products, such as grape skins and stems, for reducing or eliminating the use of SO2 in red wine production. Special attention was focused on guaranteeing the microbiological stability of the red wines and protecting them against oxidation. Therefore, the antioxidant and antimicrobial activities of the extracts and red wines were studied. Red grape stems and skins, by-products of the wine industry, from six types of monovarietal wines, were used. Extracts obtained from stems displayed higher concentrations of total phenolic compounds and higher in vitro antioxidant activity. Both stem and skin extracts demonstrated higher antimicrobial activity against pathogenic bacteria and lower activity against yeasts. In the wines produced, higher antimicrobial and antioxidant activities were observed, mainly in the skin extract batches. This study highlights that bioactive extracts obtained from by-products of wine making could be used to reduce or eliminate the use of SO2 in wine production. In this way, healthier red wines could be obtained while guaranteeing their microbiological stability and protecting them from oxidation. Furthermore, the use of these by-products is strongly associated with the circular economy, as they could help to reduce the environmental impact of the wine industry.

Thesis (MScAgric)--Stellenbosch University, 2003.
ENGLISH ABSTRACT: Wine cellars are diverse in terms of equipment types and process configurations. Whilst other food production processes have, in many cases, been properly analysed and modelled, this process diversity has resulted in an absence of process analyses in the wine industry. Each wine cellar is unique and represents a fully integrated agro-business, starting with a raw material (grapes) and extending to marketing and selling of the final product (wine). This makes the wine industry unique in this context. This study is the first attempt to analyse winemaking procedures in the form of a process audit. The study was approached in the following manner: • A questionnaire was developed to assess cellar configurations and conditions. This questionnaire was submitted to a statistically significant number of cellars, and a statistically significant number of questionnaires were returned. • The data collected from the questionnaire were statistically analysed and associations between equipment or procedures and wine faults were identified. • Three cellars were studied in depth. These three cellars had their processes audited and their effluent characterised. Additional data were obtained from current sampling projects and these data were analysed to complement the data obtained from the questionnaire • A preliminary input/output model was developed. The major results of this study are: • It was found that certain faults that appear in wine might be associated with equipment and/or process faults. These associations are statistically significant and they show that cellar hygiene is of critical importance when assessing these wine faults. The most important of these faults are VA, microbial contamination of the wine, sluggish and stuck fermentations. A risk hierarchy was derived to indicate which events are associated with others most strongly. • It was found that few wineries measure water consumption and even fewer wineries measure the quantity of effluent produced. • Correlations have been developed to predict winery parameters in terms of tons of grapes pressed per annum. These parameters include water and electricity consumed, wine produced and the quantity of effluent produced. Effluent characteristics have also been correlated to the tons of grapes pressed per annum. These characteristics include chemical oxygen demand, sodium absorption ratio and total dissolved solids in solution. Chemical oxygen demand was identified as the most important contributing factor in winery effluent. It was shown that all variables rise with an increase in cellar size, but the rise is not linear. This implies that large cellars have greater quantities of effluent of lower quality than small cellars. Most cellars have effluent concentrations that require some form of effluent treatment. The characterisation of effluent shows that the most widely used disposal practice is irrigation, and that the effluent disposed in this manner does not meet legislative requirements. • A preliminary input/output model was developed in order to enable wineries that have not measured the relevant parameters to predict the abovementioned variations. The resolution of these predictions is low but the model serves to provide an initial estimate if there are no data available. The model will give industrial averages for any given cellar size. • An economic balance was performed using this preliminary model. It was shown that if cellars were to lower the consumption of utilities and to reduce the strength of their effluent (using cleaner practices and not dilution) the reduction of operating costs could be reduced by 14% for smaller cellars to 17% for larger cellars. This study has shown that it is possible to make wine in a more environmentally friendly manner, producing better quality wines, without incurring extra costs.
AFRIKAANSE OPSOMMING: Wynkelders is diverse eenhede ten opsigte van die tipe toerusting en prosesse wat gebruik word. Terwyl ander prosesse rondom voedselproduksie in baie gevalle reeds geanaliseer en gemodelleer is, het die diversiteit in die wynindustrie gelei tot 'n afwesigheid van prosesanalises. Elke wynkelder is uniek en verteenwoordig 'n ten voile geintegreerde agro-besigheid wat begin met die rou materiaal (druiwe) en lei tot die bemarking en verkope van die finale produk (wyn), 'n eienskap wat die wynindustrie uniek maak in hierdie verband. Hierdie studie is die eerste poging om die wynmaakproses in die vorm van ‘n proses-oudit te analiseer. Die studie is soos volg aangepak: • ‘n Vraelys is ontwikkel om kelderkonfigurasies en -toestande te ondersoek. Die vraelys is aan ‘n statisties betekenisvolle aantal kelders voorgele, en ‘n statisties betekenisvolle aantal vraelyste is terugontvang. • Die data wat uit die vraelyste ontvang is, is statisties ontleed en verwantskappe tussen toerusting of prosesse en wyngebreke is geidentifiseer. • Drie kelders is in diepte bestudeer. Hierdie drie kelders se prosesse is geoudit en die afvloeiwater is gekarakteriseer. Addisionele data is verkry van huidige projekte en hierdie data is ge-analiseer om die data van die vraelys aan te vul. • ‘n Voorlopige inset / uitset model is ontwikkel. Die belangrikste resultate van hierdie studie is: • Dit is bevind dat sekere gebreke wat in wyn voorkom geassosieer kan word met tekortkominge in toerusting en/of prosesse in die kelder. Hierdie assosiasies is statisties betekenisvol en toon dat kelderhigtene van kritiese belang is wanneer gebreke in wyn ondersoek word. Die mees belangrike gebreke wat voorkom is vlugtige suur, mikrobiese kontaminasie van wyn, slepende en gestaakte fermentasie. ‘n Risikohierargie is afgelei om die gebeure te toon wat die sterktste met mekaar geassosieer word. • Dit is gevind dat min wynkelders waterverbruik meet. Selfs minder kelders meet die hoeveelheid afvloeiwater wat geproduseer word. • Korrelasies is ontwikkel om kelderparameters te voorspel in terme van ton druiwe gepars per jaar. Hierdie parameters sluit in water- en elektrisiteitsverbruik, wyn geprosuseer en hoeveelheid afvloeiwater geproduseer. Eienskappe van afvloeiwater is ook gekorreleer met die ton druiwe wat per jaar gepars word. Hierdie eienskappe sluit in chemiese suurstofbehoeftes, natrium absorpsieverhoudings en totale opgeloste soliede materiaal in oplossing. Chemiese suurstofbehoeftes is geidentifiseer as die mees belangrike bydraende faktor tot afvloeiwater in kelders. Dit is getoon dat alle veranderlikes verhoog hoe groter die kelder, maar hierdie verhoging is nie lineer nie. Dit impliseer dat groter kelder meer afvloeiwater van ‘n laer kwaliteit produseer. Die meeste kelders produseer afvloeiwater van sodanige konsentrasies dat behandeling daarvan nodig is. Die ondersoek van hierdie afvloeiwater toon dat die mees algemene wyse van wegdoening van afvloeiwater besproeiing is, en dat afvloeiwater wat op hierdie manier weggedoen word, nie voldoen aan die wetgewing se vereistes nie. • 'n Voorlopige inset/uitset model is ontwikkel om kelders wat nie die toepaslike parameters gemeet het nie in staat te stel om hierdie parameters te voorspel. Die akuraatheid van hierdie voorspellings is nie hoog nie, maar die model verskaf ‘n aanvanklike skatting waar daar geen data beskikbaar is nie. Die model verskaf industriele gemiddeldes aan kelders van enige grootte. • ‘n Ekonomiese balans is uitgevoer deur van hierdie model gebruik te maak. Dit is getoon dat indien kelders die gebruik van water en elektrisiteit verminder en die konsentrasie van afvloeiwater verlaag (deur van skoner paktyke gebruik te maak, en nie verdunning nie) die bestuurskoste met 14% vir kleiner kelders tot 17% vir groter kelders verlaag kan word. Die studie het getoon dat dit moontlik is om wyn te maak op ‘n meer omgewingsvriendelike wyse, en sodoende beter kwaliteit wyn te produseer sonder addisionele kostes.

Thesis (MScAgric)--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: Ferdinand de Lesseps grapes have a distinctive fruity varietal character and were often used judiciously by wine-makers to enhance the fruity bouquet of some white table wines. Ferdinand de Lesseps grape juice was investigated to identify the main contributing compounds responsible for its unique and intense aroma. The juice was recovered from grapes under anaerobic conditions and extracted using Freon 11. The concentrated extract was analysed using a combination of capillary gas chromatography-mass spectrometry and gas chromatography-sniffing techniques. Thirty-two compounds were reported. With the aid of GC-sniffing, it was concluded that the hybrid note of the Ferdinand de Lesseps grape was most likely attributed to the presence of 2,5-dimethyl-3(2H)-furanone and 0- aminoacetophenone. Esters, which featured prominently in the juice, consisted mainly of ethyl butanoate, ethyl- and methyl- 3-hydroxy butanoate, and to a lesser extent, ethyl 3- hydroxy hexanoate and ethyl-3-hydroxy propanoate. These esters are most likely responsible for the sweetish pineapple aroma. According to EEC regulations, the use of non- Vinifera grapes in the production of commercial wines is prohibited. The presence of 2,5-dimethyl- 3(2H)-furanone in wine could therefore be interpreted as a labrusca indicator should it be suspected that Ferdinand de Lesseps grapes were used in the blend. The quality of some South African Kerner table wines often is rated inferior owing to an unwanted odour described as "Elastoplast" or "medicinal". This odour is encountered occasionally in wines from other cultivars such as Gewurztraminer, Weisser Riesling, Muscat de Frontignan and Chenin blanc. The identification of the compounds responsible for the offodour was investigated, as well as possible relationships between its occurrence and viniviticultural practices. The compound responsible for the "medicinal" off- odour was identified as p-vinyl guaiacol. It is formed via decarboxylation of ferulic acid by yeast during alcoholic fermentation. lts concentration is directly related to the concentration of ferulic acid and the yeast strain. Other factors affecting p-vinyl guaiacol formation in Kerner wines are region, microclimate, exposure of grapes to sunlight and grape maturity. Wines made from grapes harvested from the warmer climatic regions and exposed to direct sunlight and increased maturity contained higher levels of p-vinyl guaiacol. Viticultural practices that can be applied to limit the formation of the p-vinyl guaiacol precursor in grapes are the use of a canopy manipulation to protect the grapes from direct sunlight and an earlier harvesting date. Various winemaking techniques can be used to lower p-vinyl guaiacol levels in wine. Careful consideration must be given to the choice of yeast, as different yeast strains differ considerably with their ability to form p-vinyl guaiacol. Fining oxidised grape juice with phenol adsorbing agents such as activated charcoal, polyvinylpolypirrollidone, casein, gelatin (particularly in combination with bentonite and "kieselsol") led to decreases in the p-vinyl guaiacol levels. Although fining with activated charcoal was the most effective must treatment for reducing the "medicinal" aroma of Kerner wines, it stripped the wines of colour and character. Excessive oxidation of must followed by fining involves extra costs and time for the winemaker and would not be used in making the reductive style of wines.
AFRIKAANSE OPSOMMING: Ferdinand de Lesseps druiwe en wyne vertoon unieke vrugtige varieteitskarakter en is dikwels deur wynmakers in versnitte gebruik om die geur van sekere wit tafelwyne te verbeter. In hierdie studie is Ferdinand de Lesseps druiwe ondersoek om die belangrikste komponente wat verantwoordelik is vir die prominente, unieke aroma daarvan te identifiseer. Die sap is onder anaerobe toestande herwin en met Freon 11 ekstraheer. Die gekonsentreerde ekstrakte is met behulp van 'n kombinasie van kapillêre gaschromatografie-massaspektrometrie en gaschromatografie-snuif tegnieke analiseer. Twee-en-dertig komponente is gerapporteer. Met die behulp van GC-snuiftegnieke is bevestig dat die hibried karakter in Ferdinand de Lesseps druiwe hoofsaaklik aan die teenwoordigheid van o-amino-asetofenoon en 2,5-dimetiel-3(2H)- furanoon toegeskyf kan word. Die vernaamste esters in die sap was etielbutanoaat, etiel- en metiel-3-hidroksibutanoaat en in 'n mindere mate etiel-3-hidroksiheksanoaat en etiel-3- hidroksipropanoaat. Dié esters is waarskynlik verantwoordelik vir die soet pynappel aroma. Volgens EEG regulasies word die gebruik van nie- Vinifera druiwe vir die produksie van komersiéle wyne verbied. Die teenwoordigheid van 2,5-dimetiel-3(2H)-furanoon in wyn kan dus interpreteer word as 'n labrusca indikator in gevalle waar gebruik van Ferdinand de Lesseps druiwe vermoed word. Die kwaliteit van sommige Suid-Afrikaanse Kerner wyne word dikwels verlaag vanweë die teenwoordigheid van 'n geur wat beskryf word as "Elastoplast" of "medisinaal". Dié reuk word soms waargeneem in wyne van ander kutivars soos Gewurztraminer, Weisser Riesling, Muskaat de Frontignan en Chenin blanc. Die identiteit van die komponent wat vir dié ongewenste reuk verantwoordelik is, asook moontlike verwantskappe met wingerd- en wynkundige praktyke is ondersoek. Die komponent wat vir die medisinale karakter verantwoordelik is, is geïdentifiseer as para-vinielguajakol. Dit word deur dekarboksilasie van feruliensuur deur gisselle tydens alkoholiese gisting gevorm. Die konsentrasie van paravinielguajacol in wyn is direk verwant aan die konsentrasie feruliensuur en die gisras. Ander faktore wat para-vinielguajacol-vorming in Kerner wyn affekteer is streek, mikroklimaat, blootstelling van druiwe aan direkte sonlig en die rypheidsgraad van die druiwe. Wyne wat berei is van ryper druiwe uit warmer streke en wat direk aan sonlig blootgestel was, het hoër konsentrasies para-vinielguajacol bevat. Lowerbestuurspraktyke met behulp waarvan druiwe teen direkte sonligblootstelling beskerm word, is van die vernaamste wingerdkundige praktyke wat aangewend kan word om die vorming van die voorlopers van paravinielguajacol in druiwe te verlaag. Verskeie wynbereidingstegnieke kan gebruik word om die para-vinielguajacol vlakke in wyn te verlaag. Gisraskeuse is van besondere belang omdat gisrasse grootliks verskil in hul vermoë om para-vinielguajacol te vorm. Breibehandelings van geoksideerde sap met middels soos geaktiveerde koolstof, PVPP, kasseïen, gelatien (veral in kombinasie met bentoniet en "kieselsol") het die vlakke van para-vinielguajacol in wyne verlaag. Hoewel geaktiveerde koolstof die doeltreffendste breimiddel vir die verlaging van para-vinielguajacol was, het dit te veel kleur en geur uit die wyn verwyder. Oormatige oksidasie van mos gevolg deur breibehandelings sal meer geld en tyd verg en word nie aanbeveel vir wyne wat in 'n reduktiewe styl berei word nie.

Thesis (MScAgric)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The quality of wine is largely dependent on environmental conditions and recent studies have therefore focused on agricultural practices in terms of water, soil and biodiversity conservation. The industry aims to create sustainable practice and to protect the natural resources available. Sources of potential grape contamination include: vehicle pollution, pesticides, bushfires and wood preservatives used for trellising systems. The latter have come to the attention of the South African wine industry (e.g. creosote and Copper Chromium Arsenate (CCA) products) as they may have consequences for the environment and wine quality. Creosote is a known pollutant of soil and ground water and the volatile fraction has been monitored in air. Plants may also accumulate polycyclic aromatic hydrocarbons (PAHs), which constitute up to 85% of the mass of creosote, and of which some have been proven carcinogenic. Because of the health risks associated with it, creosote has therefore been restricted for use in most applications in Europe, and also in the United States, Canada and Australia. This study focussed on the sensorial and chemical analyses of environmental and wine samples taken from the area around the creosote stockyard to determine accumulation of creosote-derived compounds. Environmental samples were collected and analysed at different distances from the affected area, over two vintages. Wines were made from grapes grown in vineyard blocks adjacent to the stockyard, to determine the effect of distance and skin contact during alcoholic fermentation treatments on wine taint. A sensory panel was trained for descriptive analysis to determine the intensity of the taint. Analytical methods were developed for the analysis of volatile organic compounds (VOCs) by gas chromatography mass spectrometry (GC-MS) and polycyclic aromatic hydrocarbons by high performance liquid chromatography with diode array detection (HPLC-DAD). The sensory results obtained showed white and rosé wines were perceived as clean, whilst the red wines were associated with burnt rubber/tar taint. The perceived taint decreased as distance from the stockyard increased. Wines made from the Cabernet Sauvignon blocks adjacent to the stockyard also showed an increase of taint with the increase of skin contact. Chemical data obtained showed that the taint consisted of a complex mixture of compounds, each with its own pattern of retention within the vineyard and wine. Only m-cresol was found above odour threshold, and only in red wines. The synergistic effect of some compounds may lead to an increase in the perceived taint. Berries and leaves had higher concentrations of volatile compounds than wines. Leaf contamination varied and followed the general trend in literature where the plants with high lipid content and exposed leaf area were the most contaminated. There may be other compounds present in creosote emissions, aside from those investigated here, with sensory attributes related to the taint found in wines. These compounds are styrene, indene, benzene, toluene, isoquinoline and quinoline and should be included in further investigations. From the PAH analysis of environmental samples and wines, it is evident that the samples closest to the stockyard were affected the most. The contamination varied with the depth of the soil: some of the heavier compounds were found in the samples taken from the deeper levels, whilst nearly all other target compounds were present in the top layer of soil. The concentrations found in the environmental samples were lower than reported in literature. Wines had few PAHs present, but at much higher concentrations than is allowed by EU legislation. From this study it is evident that the stockyard had negative effects on the surrounding environment in terms of sensory and chemical contamination. Recommendations include area rehabilitation by means of bioremediation to protect resources and ensure sustainable and safe production of crops. Industrial emissions should also be regulated and restricted in agricultural areas. Furthermore the use of creosote should be revised, and prohibited for agricultural use.
AFRIKAANSE OPSOMMING: Die kwaliteit van wyn is grootliks afhanklik van die omgewingstoestande. Daarom fokus verskeie onlangse studies op landbou aktiwiteite en die invloed daarvan op die omgewing in terme van water, grond en biodiversiteit bewaring. The wyn industrie se doelwitte sluit volhoubare praktyke in, wat die natuurlike hulpbronne bewaar en beskerm. Druiwe kan deur middel van die volgende bronne besoedel word: brandstof uitlaatgasse, insekdoders, veldbrande, gifstowwe wat gebruik word vir houtperservering wat dan verder aangewend word vir opleistelsels. Houtperservering (Koper chroom arsenaat (CCA) en kreosoot) het veral in die laaste paar jaar onder aandag gekom in die wynbedryf van Suid-Afrika as gevolg van die invloed daarvan op die omgewing en die uiteindelike wynkwaliteit. Kreosoot is ‘n gekende gifstof wat verantwoordelik is vir grond en grondwater besoedeling en wat gemonitor word in die atmosfeer. Plante akkummuleer ook poli-sikliese aromatiese hidro-koolstowwe (PAHs), wat to 85% uitmaak van die massa van kreosoot. PAHs is karsinogenies en dus is daar baie navorsing op die molekules reeds gedoen. Die gesondheidsrisikos gepaardgaande met kreosoot het gelei tot die streng geregulasies tans ingestel in Europa, die Verenigde State, Kanada en Australië. Hierdie studie het gefokus op die sensoriese en chemiese analises van omgewings- en wyn-monsters geneem van die omliggende area van die kreosoot palewerf om die akkumulasie van kreosoot-afgeleide-verbindings. Omgewingsmonsters was versamel en geanaliseer om verskillende afstande vanaf die bron van besoedeling (palewerf) te ondersoek oor ‘n twee jaar periode. Wyne is gemaak van die druiwe wat afkomstig is van die blok aangeplant langs die palewerf. Die wyne is ondersoek in terme van afstand vanaf die kreosoot bron asook oenologiese invloede, dopkontak gedurende alkoholiese fermentasie, op die kontaminasie beskryf in wyn. Die wyne is ook oor ‘n twee jaar periode voorberei en sluit die 2011 en 2012 seisoen in. ‘n Sensoriese paneel is opgelei om die beskrywende analises op die wyn uit te voer met die doel om die intensiteit van kontaminasie te identifiseer. Analitiese metodes is ook ontwikkel vir die analise van vlugtige organiese verbindings(VOCs) met gas chromatografie-massa spektrometrie (GCMS) en poli-sikliese aromaties hidro-koolstowwe (PAHs) met hoë druk vloeistof chromatografie. Die sensoriese resultate bekom het wit en rosé wyne as skoon laat blyk, terwyl rooi wyne meer geassosieer was met die gebrande rubber/ teer afgeur beskrywing. Die waargeneemde afgeur het afgeneem soos wat die afstand vanaf die palewerf toegeneem het. Wyne gemaak van die Cabernet Sauvignon blokke langsaan die palewerf het ook ‘n toename in die afgeur gehad met ‘n toename in dopkontak. Chemiese data bekom beeld uit dat die afgeur uit ‘n komplekse mengsel van verbindings bestaan, elk met sy eie patroon van verspreiding en verbinding in die wingerd as ook in die wyn. Net m-kresol was gevind bo die reuk drumpel, dit het ook net in rooi wyne voorgekom. Die sinergistiese effek van die verbindings mag egter bydra tot die waargeneemde afgeur. Druiwekorrels en blare het hoër konsentrasies van die vlugtige verbindings gehad as wat gemeet is in die wyne. Blaar kontaminasie het ook baie gewissel en het ooreengestem met die algemene tendens wat in literatuur beskryf is, naamlik dat plante met ‘n hoër lipid inhoud en grootter blaar oppervlak die meeste gekontamineer word. Daar mag egter nog baie ander verbindings bydra tot die waargeneemde afgeur gevind in die wyn. Spesifieke verbindings wat wel ‘n rol kan speel in kontaminasie en wat voorkom in die vlugtige gedeelte van kreosoot is styreen, indeen, benzeen, tolueen, isoquinoleen die vlugtige verbindings van kreosoot. Die verbindings moet ingesluit word vir verdere studies wat gedoen word op die kreosoot geassosieerde afgeur. Die PAHs analise op die omgewingsmonsters en wyne het gelei tot die bevestiging dat die naasliggende omgewing die meeste geaffekteer is. Die kontaminasie wissel in terme van die diepte in die grond wat die gifstowwe voorkom: die swaarder molekulêre verbindings is tot in die dieper vlakke waargeneem terwyl al die gemete verbindings in die boonste lae teenwoordig was. Die vlakke wat waargeneem is in dié studie is egter laer as wat voorheen in literatuur gevind is in ‘n kreosoot geaffekteerde omgewing. Wyn het PAHs teenwoordig gehad, alhoewel slegs twee verbindings gemeet is, het dit in hoër vlakke voorgekom as wat sekere Europese regulasies as toelaatbaar spesifiseer. Vanaf die studie resultate blyk dit, dat die palewerf se negatiewe invloed op die omliggende omgewing beide meetbaar was in sensories en chemiese kontaminasie. Voorstelle sluit onder andere die rehabilitasie van die omliggende omgewing deur middel van bioremediasie in. Om sodoende die natuurlike hulpbronne in die area te bewaar asook om volhoubare en veilige verbouing van gewasse te verseker. Industriële besoedeling en afval moet ook gereguleer word en beperk word in landbou areas. Verder moet die gebruik van kreosoot heroorweeg word en strenger regulasies moet in plek gestel word om aan internastionale standaarde te voldoen.
Financial support from Winetech, Trip and UFS

Thesis (MScAgric) -- Stellenbosch University, 2005.
ENGLISH ABSTRACT: Winemakers or producers are under constant pressure to reduce the operational costs for the production of wine. The reason for this being threefold: Firstly, the number of cellars and estates locally, and internationally, has grown immensely. Thus, the competition on both the national and international front has put producers under pressure to reduce their production cost in order to survive the explosion of brand possibilities on the consumer's horizons. Secondly, the exchange rate has been one of the most unpredictable variables which highlight the importance of scenario planning and sufficient financial planning in order to overcome significant exchange rate fluctuations which may cause financial strain for the business. Thirdly, the benefits of using expensive oak barrels for the maturation of premium quality wines are undisputable. These benefits include the clarification and decarbonation of wines, decrease in the astringency of tannins ("softening of tannins"), the evolution of colour, providing complementary oak aromas which increase the complexity and finesse of these wines and stabilising the colloid structure of the maturing wine. The greatest disadvantages remain nevertheless that it is a costly and labour intensive operation. Oak is an essential part of the flavour profile of many premium quality wines, and there is still a growing market demand for these wines. The use of oak barrels for the maturation of premium red wines, incorporates a specific flavour dimension to the wine (and adding value), has been the traditional way of storing wines. Well known cellars and Estates all over the world have build remarkable profiles and identities for their brands. To alter any principles regarding the use of oak will alter the style of the wines and will beyond any doubt influence their brand image negatively. Chapter 1 gives an introduction and the main aims of the study. The phenolic composition of grapes and oak are a complex mixture of different molecules which are discussed in Chapter 2. These include those responsible for the colour (anthocyanins), taste (mainly the tannins) and aroma of the wine. The composition of the oak barrel can be influenced by its origin, seasoning of the oak, toasting of the staves, age of the barrel etc. These factors all affect the chemical composition of the oak (lactones, volatile phenols, carbohydrate volatiles, hydrolysable tannins etc.) and ultimately, the wine. The chemical reactions taking place in wine during ageing are also complex, which makes maturation and research of wine in oak a complex business. The challenge, thus, developed to sustain the flavour profiles (oak attributes) and to reduce the operational costs, without influencing the identity or profile of the brand negatively. The use of oak derived products like chips, dust, blocks, staves, balls and even extracts was proposed, although it is considered by-products of the cooperage profession. Some of the major disadvantages of the use of oak derived products still remain the limited control over the production process. This may lead to inconsistency in the quality of these products. Nevertheless, the use of oak derived products and the availability of these products have grown significantly and with it a need for research on this field. Chapter 3 address the results obtained from the maturation of Pinotage, which is uniquely South African, and Shiraz wines, in different oak type barrels (French vs. American vs. Russian), as well as treatments with various oak derived products, and the influence of these oak products on the evolution of colour, phenolic development and quality of the wines during ageing. The results obtained in this project correlated with findings in the literature. The colour density, percentage of red pigment colour and S02 resistant pigments increased, especially in the first three to six months during ageing in barrels as a result of ellagic tannin extraction from the barrels and polymerisation reactions, but decreased later as maturation progresses as a result of precipitation. In some cases the use of oak increased the colour density significantly with almost 40%. The colour density, total red pigment colour and total phenolic composition decreased during bottle maturation as a result of polymerisation. No significant colour differences between the barrel types could, however, be detected. The use of oak derived products showed the same tendencies for all colour dimensions, although no significant differences could be detected between the treatments. The most significant difference was that new oak barrels contributed more to the development of colour compared to the oak treatments. The Gelatine index gives an indication of the degree of polymerisation of tannins; higher values will indicate tannins which are highly reactive and will cause an astringent mouth feel. The values should decrease as maturation progresses and tannins polymerise. Little differences between barrel types (French vs. American vs. Russian) were found in the one Shiraz, but in the two Pintage wines the index was the lowest in the wines matured in French oak after 36 months bottle ageing. Sensorial tests indicated little quality differences after 36 months between the different oak types The American oak barrels had, in general, a more "oaky bouquet", even after 36 months in the bottle. Pinotage matured with different alternative oak products showed that chips added to barrels tended to give a higher oak aroma, with a lower fruit compared to the other treatments. The same wine matured in new barrels, as expected, also had a very high oak aroma compared to the same wine matured in older barrels. This led to a higher fruit perception in the latter wines. Lees contact is a practice more commonly used in the production of white wines, but may be a dangerous practice in the production of red wines. Chapter 4 reports on the effect of lees contact during ageing of red wine on the micro flora and colour after 12 month maturation. No significant differences in microbial analysis were detected during of barrel maturation between the wines matured in the lees and the filtered wines for acetic acid, yeast and lactic acid bacteria. The initial pH differences during cold maceration and fermentation, however, did influence these numbers, with higher numbers being observed at higher pH values. However, colour differences could be detected. The concentration of yellow brown pigments (measured at 420 nm) was lower in the lees matured wines than in the filtered· wines which underwent malolactic fermentation in the barrel. Other colour differences that could be detected were higher colour density and total red pigment colour in wines as a result of longer skin contact (due to slower alcoholic fermentation rate). Thus, manipulation of the skins during alcoholic fermentation, the use of barrels and/or oak derived products in various stages of vinification and maturation of wines and additional practices as maturation on lees may be thus be used to set a certain style of wine which meet a specific market demand, trend or style. Chapter 5 summarises the results obtained and future research to be done on wood and wine. This study, however, clearly showed that the origin and oak type does not influence the colour as much as the aroma and taste of red wine under South African conditions.
AFRIKAANSE OPSOMMING; Wynmakers of produsente word onder gedurige druk geplaas om die produksiekoste van wyn te verlaag. Die redes hiervoor is drieledig: Eerstens het die getal kelders en landgoedere op nasionale en internasionale vlak geweldig toegeneem. Dus, die kompetisie op beide nasionale en internasionale gebied plaas produsente onder druk om die produksie koste van die wyn te verminder om sodoende finansieel die ontploffing van nuwe moontlike wyne op die horison van die verbruiker te oorleef. Tweedens, die wisselkoers was altyd een van die meer onvoorspelbare veranderlikes wat die belangrikheid van scenario-beplanning en weldeurdagte finansiele beplanning beklemtoon om sodoende groat veranderinge in die wisselkoers, wat moontlike finansiele druk in die besigheid mag veroorsaak, te oorkom. Derdens, een van die grootste uitgawes in die produksie proses van is die verouderingskomponent van kwaliteitswyn. Die voordele van die gebruik van eikehout vate in die verouderingsproses van rooiwyne is welbekend. Hierdie voordele sluit in die suiwering van die wyn in terme van soliede partikels , dekarbonisering (C02-ontgasting}, afname in die vrank smaak ("sagtheid van die tanniene), die ontwikkeling van die kleur van die wyn, toevoeging van komplementere hout boeketstowwe wat bydrae tot die kompleksiteit van die wyn, asook die stabilisering van die kollo"idale struktuur van die wyn. Die grootste nadeel bly, nieteenstaande, die geweldige koste verbonde aan vate, asook die hantering en onderhoud daarvan. Eike hout verwante boeketstowwe is 'n onmisbare komponent van die aroma profiel van baie kwaliteitswyne. Daar is 'n groeiende mark vir hierdie tipe wyne. Die gebruik van eikehout vate vir die veroudering van kwaliteitswyne, behalwe die bydrae van belangrike geurstowwe (een waarde), was nog altyd 'n tradisionele stap in die proses. Beroemde kelders reg oor die wereld het uitmuntende mark identiteite vir hulle self geskep, asook 'n "spesifieke identiteit" vir hulle wyn. Om enige beginsels aangaande die gebruik van eikehout te verander, sal sander twyfel die wynstyl verander en moontlik 'n negatiewe effek op die kelder se identiteit he. Hoofstuk 1 gee 'n inleiding en die hoof doelstellings van die studie. Die fenoliese samestelling van druiwe en eikehout bestaan uit 'n komplekse mengsel van verskillende molekules wat in Hoofstuk 2 beskryf word. Hierdie sluit in daardie verantwoordelik vir die kleur (antosianiene), die smaak (hoofsaaklik tanniene) en die aroma van die wyn. Die samestelling van die eikevat kan beinvloed deur die oorsprong, veroudering van die hout, roostering, ouderdom van die vat ens. Hierdie faktore beinvloed almal die samestelling van die houtvat (laktone, vlugtige fenole, hidroliseerbare tanniene ens.) en uiteindelik, die wyn. Die chemiese reaksies wat plaasvind tydens die veroudering van wyn is ook kompleks, wat die veroudering en navorsing van wyn in vate 'n komplekse proses kan maak. Die uitdaging, dus, het ontstaan om die organoleptiese profiel van die wyn (eikehout boeketstowwe) te behou en terselftertyd die produksiekoste van die wyn te verlaag. Die gebruik van eikehout verwante produkte soos skaafsels, blokkies, stawe en balke en selfs eikehout ekstrakte is aanbeveel, alhoewel dit gesien word as afvalprodukte van die kuiperye Een van die grootste nadele van eikehout alternatiewe produkte is egter die beperkte kwaliteitskontrole oor die produksieproses. Dit mag lei tot wisselvalligheid in die kwaliteit van hierdie produkte. Nieteenstaande het die gebruik van eike houtverwante produkte en die beskikbaarheid van hierdie produkte geweldig toegeneem en tesame daarmee die behoefte aan navorsing hieroor. Hoofstuk 3 bespreek resultate van die gebruik van verskillende eikehout tipe vate (Frans vs Russies vs Amerikaans), asook die gebruik van eikehout verwante produkte, op die kleur ontwikkeling, fenoliese samestelling en kwaliteit van Pinotage (eie aan Suid-Afrika) en Shiraz wyne gedurende vat en bottel veroudering. Die ontwikkeling van kleur het verskeie unieke dimensies en resultate wat verkry is in hierdie projek stem ooreen met literatuur. Die kleurdigtheid, persentasie rooi pigment en 802 weerstandbiedende pigmente het toegeneem met veroudering in houtvate (veral in die eerste drie tot ses maande) as gevolg van ellagitanniene wat geekstraeer word en gepolimerisasie, maar het later gedurende veroudering afgeneem as gevolg van presipitasie reaksies. In sekere gevalle het die kontak met hout die kleurdigtheid met tot 40% vermeerder. Die kleurdighteid, totale rooi pigmente en totale fenole het tydens bottelverouding afgeneem a.g.v. polimerisasie. Geen merkwaardige verskille kon egter tussen die verskillende vattipes gevind word nie. Verskille tussen die houtverwante produkte was ook klein en het diesefde tendense getoon as die vate. Nuwe vate se impak op die kleurprofiel en ontwikkeling van verouderde rooiwyne was egter meer beduidenswaardig as die gebruik van gebruikte vate en behandelings met eikehout verwante produkte. Die gelatien indeks verwys na die toestand van polimerisasie van tanniene. Hoer waardes kan verwag word in jong wyne en dui op hoogs reaktiewe tanniene. Die waarde sal afneem soos tanniene polimere vorm met veroudering en sal dus 'n veel minder vrank mondgevoel tot gevolg he. Klein verskille tussen die vat tipes (Frans vs Amerikaans vs Russies) is opgemerk in die een Shiraz, maar in die twee Pinotage wyne was die indeks die laagste in die wyne verouder in Franse eikehout na 36 maande se bottelveroudering. Sensoriese toetse het aangedui dat daar klein verskille gevind is tussen die verskillende eiketipes. Die wyn verouder in Amerikaanse eik het, in die algemeen, 'n sterker eikehoutkarakter gehad na 36 maande bottelveroudering. Wyn verouder met verskillende alternatiewe houtprodukte het aangetoon dat eikehouskaafels in vate 'n sterker eikehoutkarakter aan die wyn gegee het met 'n laer vrugtige aroma in vergelyking met die ander behandelings. Dieselfde wyn verouder in nuwe vate het oak, soos verwag, 'n sterk hout boeket gehad in vergelyking met die verouder in ouer vate. Dit het dan oak gelei dat laasgenoemde wyne 'n sterker vrug aroma gehad het. Veroudering van wit wyne op moer is 'n algemene praktyk, alhoewel dit minder toegepas word op rooiwyne as gevolg van verwante gevare. Hoofstuk 4 bespreek die effek van moerkontak op die mikrobiese en kleursamestelling van rooiwyn tydens 12 maande se houtveroudering. Geen noemenswaardige verskille is egter verkry tussen die wyne verouder op die moer en die filtreerde wyne vir asynsuur-, melksuurbateriee en gisgetalle nie. Aanvanklike pH verskille tydens koue masserasie en alkoholiese fermentasie het egter hierdie getalle beinvloed, met hoer ·getalle verkry in die hoer pH wyn. Die wyne wat appelmelksuurgisting in die vate ondergaan het en verouder is op die moer het egter 'n laer konsentrasie geelbruin pigmente (gemeet by 420 nm) as die gefiltreerde wyne. Ander kleurverskille sluit in hoer kleurdigtheid en totale rooi pigmente as gevolg van langer dopkontak (stadiger alkoholiese fermentasie). Manipulering van die doppe voor en tydens alkoholiese gisting, die gebruik van eikehoutvate of eikehoutverwante produkte, of kombinasies daarvan tydens verskillende produksie fases en ander praktyke soos moer kontak, kan dus gebruik word am 'n sekere styl wyn op markversoek daar te stel. Hoofstuk 5 som die resultate op, asook toekomstige navorsingsmoontlikhede wat op die gebied van hout en wyn gedoen kan word. Hierdie studie het egter duidelik aangedui dat die eikehout oorsprong en tipe die kleur nie so baie beinvloed soos die aroma en smaak van die wyn onder Suid-Afrikaanse kondisies nie.

Thesis (PhD)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: During wine fermentation, numerous grape must constituents serve as nutrients to wine yeast (Saccharomyces cerevisiae), which enable their growth and successful completion of alcoholic fermentation. Many of these nutritional factors, in particular nitrogen, also act as precursors for yeastderived flavour compounds such as higher alcohols, esters and volatile fatty acids. Yeast nitrogen metabolism thus plays a determining role in wine aroma and quality. Not only is the nitrogen source, concentration and supplementation timing important, but various environmental factors and the genetic constitution of the yeast strain used for fermentation will also contribute to fermentation outcomes. The main goal of this work was to explore the complex interactions between a number of contributing factors; namely nitrogen source, timing of addition, yeast strain and fermentation matrix. Broadly, this study assessed the impact of seven different nitrogen combinations, added either to the initial grape must or after the onset of fermentation, on fermentation performance and aroma compound production by nine commercial wine yeast strains. Fermentations were done in synthetic grape must, and validated for a subset of parameters in real grape must. The nitrogen treatments were designed according to the generally established order of preference of S. cerevisiae for individual amino acids as source of nitrogen under fermentative conditions, and the potential of certain amino acids to participate in metabolic pathways that produce specific aroma compounds. The results reveal that different nitrogen combinations can lead to unexpected aroma outcomes, depending strongly on the genetic background of individual yeast strains and the timing of nitrogen addition. Certain nitrogen treatments consistently resulted in significant increases or decreases in specific aroma compound concentrations in comparison to the treatment fermented on ammonium as only nitrogen source, for multiple yeast strains. These compounds were classified as nitrogen treatment dependent. Other aroma compounds were produced similarly for all nitrogen treatments and were designated as nitrogen treatment independent. The presence of specific amino acid groups (for example the branched-chain and aromatic amino acids) could be correlated to significantly altered production patterns of related (such as higher alcohols) or unrelated (diethyl succinate) aroma compounds relative to the other nitrogen treatments. Taken together, a number of interesting and novel hypotheses regarding the metabolic pathways involved could be derived from the data. Ultimately, this initial assessment of interactive effects during fermentation will contribute to practical guidelines for winemakers to allow matching grape must constituents (such as nutrients) with the intrinsic aroma production capabilities of specific yeast strains in order to modulate wine aroma, style and quality.
AFRIKAANSE OPSOMMING: Tydens wynfermentasie dien talle druiwemosbestanddele as voedingstowwe vir wyngis (Saccharomyces cerevisiae) wat hul groei bevorder en hul in staat stel om alkoholiese fermentasie suksesvol te voltooi. Baie van hierdie voedingstowwe, veral stikstof, dien ook as voorlopers vir geurkomponente afkomstig van gismetabolisme, soos hoër alkohole, esters en vlugtige vetsure. Die stikstofmetabolisme van gis speel dus ‘n bepalende rol in wynaroma en -kwaliteit. Nie net is die stikstofbron, konsentrasie en tydsberekening van stikstof toevoeging belangrik nie, maar verskeie omgewingsfaktore, asook die genetiese samestelling van die gisras aangewend vir fermentasie, sal bydra tot die fermentasie uitkomste. Die hoofdoel van hierdie werk was om die komplekse interaksies tussen ‘n aantal bydraende faktore te ondersoek; naamlik die stikstofbron, tyd van stikstof toevoeging, gisras en fermentasiematriks. Breedweg het hierdie studie die impak van sewe verskillende stikstofkombinasies, toegedien tot die druiwemos voor of na die aanvang van fermentasie, op die suksesvolle verloop van fermentasie en die produksie van aromakomponente deur nege kommersiële wyngisrasse bepaal. Fermentasies is in sintetiese druiwemos uitgevoer, en ‘n deelversameling van die fermentasies in regte druiwesap te herhaal. Die stikstofbehandelings is ontwerp in ooreenstemming met die algemeen vasgestelde voorkeurvolgorde van S. cerevisiae vir individuele aminosure as stikstofbron onder fermentatiewe kondisies, en die potensiaal van sekere aminosure om mee te doen in metaboliese paaie wat spesifieke aromaverbindings produseer. Die resultate toon dat verskillende stikstofkombinasies tot onverwagte aroma-uitkomste kan lei wat sterk afhanklik is van die genetiese agtergrond van individuele gisrasse en die tyd van stikstof byvoeging. Sekere stikstofbehandelings het konsekwent, vir veelvuldige gisrasse, tot beduidende toenames of afnames in die konsentrasies van spesifieke aromakomponente gelei in vergelyking met die behandeling wat ammonium as enigste stikstofbron bevat het. Hierdie verbindings is as stikstofbehandeling afhanklik geklassifiseer. Ander aromaverbindings is soortgelyk vir alle stikstofbehandelings geproduseer en is aangewys as stikstofbehandeling onafhanklik. Die teenwoordigheid van spesifieke aminosuurgroepe (byvoorbeeld die vertakte-ketting en aromatiese aminosure) kon gekorreleer word met beduidende veranderings in produksiepatrone van verwante (soos hoër alkohole) of onverwante (dietielsuksinaat) aromakomponente relatief tot die ander stikstofbehandelings. Alles inaggenome kon ‘n aantal interessante en nuwe hipoteses rakende die betrokke metabolise padweë van die data afgelei word. Uiteindelik sal hierdie aanvaklike bepaling van interaktiewe effekte tydens fermentasie bydra tot praktiese riglyne vir wynmakers, wat hulle in staat sal stel om druiwesapbestanddele (soos nutriënte) te strook met die intrinsieke aromaproduksie kapasiteite van spesifieke gisrasse, en sodoende wynaroma, styl en kwaliteit te moduleer.
Oenobrands and THRIP for funding this project

Thesis (MSc)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Nitrogen composition of grape must is highly variable and impacts on the health of the fermenting yeast population as well as the formation of aroma and flavour compounds in wine. Insufficient yeast assimilable nitrogen (YAN), mostly consisting of amino acids and ammonium, can lead to stuck or sluggish fermentations as well as the formation of undesirable compounds such as H2S. Furthermore, it is well established that the total concentration of YAN and the specific amino acid composition have a significant impact on the final aroma and flavour of wines. However, the impact of individual amino acids and of specific amino acid compositions on fermentation kinetics and on the production of aroma and flavour impact compounds under winemaking conditions is not well understood. The first goal of this study was to evaluate the effect of single amino acids on growth kinetics and major volatile production of two industrial wine yeast strains under conditions resembling wine fermentations. To facilitate these fermentation conditions while also allowing for easy reproducibility and manipulation of the initial components, a synthetic grape media was utilized. Biomass formation, exponential growth rate, lag phase, and fermentation duration were utilized to evaluate the efficiency of single amino acids. The data show that previously observed trends in laboratory strains mostly apply to these conditions and strains. In general, the efficiency of amino acids to be used as nitrogen sources and the production of major volatiles due to their presence followed the same patterns for both industrial yeast strains. However, the production of the secondary metabolites butanol, propanol, acetic acid, and ethyl acetate were found to be produced in different final concentrations dependent upon the yeast strain. The branched-chained and aromatic amino acids (BCAAs) treatments were observed to have the most dramatic effects on major volatile production. Investigating the relationships between the initial concentration of the BCAAs and the final concentrations of major volatile compounds, it was found that the production of fusel alcohols and fusel acids due to the degradation of BCAAs by S. cerevisiae could be predicted from the initial concentration of BCAAs. While under simple nitrogen conditions the production of several other secondary metabolites such as butanol, propionic acid, valeric acid, decanoic acid and 2-phenylethyl acetate were found to be correlated to the initial concentration of BCAAs in the media. Future studies should focus on the validation of these trends in aroma production in real grape musts under various fermentation temperatures for a number of industrial wine yeast strains.
AFRIKAANSE OPSOMMING: Die stikstof samestelling van druiwemos is hoogs veranderlik en impakteer op die kerngesondheid van die fermenterende gis populasie asook die produksie van aroma- en geurverbindings in wyn. Onvoldoende assimileerbare stikstof (ook genoem “yeast assimilable nitrogen” (YAN)), wat meestal bestaan uit aminosure en ammonium, kan aanleiding gee tot steek- of slepende fermentasies, asook die vorming van ongewensde verbindings soos H2S. Dit is alombekend dat die totale konsentrasie van YAN en dan ook die spesifieke aminosuur samestelling ‘n noemenswaardige impak op die finale aroma en smaak van wyn het. Die invloed van individuele am inosure en spesifieke aminosuur samestellings op die fermentasie kinetika, asook die produksie van verbindings met ‘n impak op die wyn aroma en smaak, word egter nie deeglik verstaan nie. Die eerste doelwit van die studie was om twee industriële gisrasse te gebruik om die effek van enkel aminosure op die groei-kinetika en produksie van die vername vlugtige verbindings onder wynmaak toestande te bepaal. Kunsmatige, gedefinieerde druiwermosmedium is gebruik om wynmaak toestande te simuleer en ook herhaalbaarheid en manipulering van die aanvanklike samestelling van die medium te verseker. Die studie het vorige tendense wat opgemerk is in die evaluasie van laboratorium rasse onder soortgelyke toestande bevestig. Die doeltreffendheid waarmee aminosure oor die algemeen gebruik word as stikstofbron, asook die produksie van die vernaamste vlugtige verbindings wat gekoppel is aan hulle teenwoordigheid, het ‘n vergelykbare patroon vir beide rasse gevolg. Die sekondêre metaboliete butanol, propanol, asetaat en etiel-asetaat is egter wel in verskillende eindkonsentrasies geproduseer deur die verskillende gisrasse. Die vertakte-ketting en aromatiese aminosuur (“branched-chained and aromatic amino acids” (BCAAs)) behandelings het die mees dramatiese effek op die produksie van die vernaamste vlugtige komponente gehad. Ondersoek na die verwantskap tussen die aanvanklike konsentraies van die BCAAs en die finale konsentrasies van dié verbindings het aangedui dat die produksie van hoër alkohole en sure, as gevolg van die afbraak van BCAAs deur S. cerevisiae, met behulp van die aanvanklike konsentrasie van die BCAAs voorspel kon word. Terselfdertyd is gevind dat onder eenvoudige stikstoftoestande, verskeie ander sekondêre metaboliete soos butanol, propionaat, valeriaat, dekanoësuur en 2-fenieletielasetaat, gekorreleer kan word met die aanvanklike BCAAs in die media. Verdere studies moet poog om hierdie tendense ten opsigte van aromaproduksie te bevestig en wel deur gebruik te maak van ware druiwemos, verskeie fermentasietemperature, asook ’n verskeidenheid van wyngisrasse.

Thesis (MScAgric)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Grapevine performance and wine quality are influenced by various factors, two of the most important being the availability and quality of irrigation water. In relatively dry countries such as South Africa the conservation and effective use of water is of utmost importance. Expected increases in temperature and decreases in rainfall in the future due to climate change impacts highlights the importance of water conservation. This inspired investigations into possible alternative irrigation water sources and therefore the possibility of vineyard irrigation using winery wastewater is of utmost importance for the sustainability of the wine industry. Winery wastewater contains higher concentrations of certain elements other than water generally used for vineyard irrigation, the most important differences being Na and K levels. Furthermore, winery wastewater contains larger populations of microorganisms such as yeasts, lactic acid bacteria and acetic acid bacteria, typical associated with wine production. If irrigation using winery wastewater affects the uptake of certain elements or alters grapevine water status, it may affect grapevine growth, juice and wine composition. Furthermore, if juice and wine composition is affected wine composition and sensorial quality may be affected. Cabernet Sauvignon/99R grapevines, growing in a sandy soil in the Breede River Valley, were subjected to eight irrigation treatments using augmented winery wastewater in addition to irrigation using raw river water as control. The study was carried out during the 2010/11 and 2011/12 seasons. The various wastewater irrigation treatments were made up by augmenting winery wastewater with raw river water to obtain a target chemical oxygen demand (COD) concentration. In this study, the level of COD in the irrigation water is a direct indication of water quality, the two being indirectly proportional. The eight wastewater irrigation treatments ranged from 100 mg/L COD up to 3000 mg/L COD. The first objective of the study was to determine the effect of irrigation using augmented winery wastewater on grapevine response, with regards to vegetative growth, berry development and berry composition. The various wastewater irrigation treatments did not affect grapevine vegetative growth or reproductive growth, including yield, throughout berry development up to harvest. Berry sugar accumulation and evolution in acid concentrations were also not affected. An increase in berry juice pH was observed with an increase in the level of COD in the augmented winery wastewater only in the second season. The amount of elements, ions and heavy metals in juice was not affected by wastewater irrigation, indicating that there was no absorption by the grapevines. Berry skin thickness, colour and phenolic content as well as yield and its associated components were not affected by irrigation using augmented winery wastewater. The second objective of the study was to determine the effect of irrigation using augmented winery wastewater on wine microbial and chemical composition, fermentation performance and wine sensorial characteristics. The natural yeast and bacteria flora of juice was not affected by the various wastewater irrigation treatments. In addition, the ability of the inoculated yeast and lactic acid bacteria strains to conduct their respective fermentation processes were not affected. With the exception of total titratable acidity (TTA) and pH, irrigation using augmented winery wastewater did not affect wine chemical composition with regards to basic wine parameters as well as colour, phenolic and tannin composition. Similar to juice, phosphorus and selected ions were not affected. None of the measured wine sensorial characteristics were affected by irrigation using augmented winery wastewater. The third objective of the study was to investigate the effect of direct contact between berries and winery wastewater on wine sensorial characteristics. The study focussed on the transference of off-flavours from the wastewater into the wine and the occurrence of off-flavours as a response to contact with winery wastewater. Wine colour and general sensory wine descriptives were not affected by direct contact with winery wastewater. The presence of a winery wastewater-like off-odour and volatile acidity was, however, more detectable in wines made from berries that were in contact with the most concentrated wastewater. Therefore, it may be possible for off-odours to be transferred from the winery wastewater into the wines, or that off-odours are formed as a direct or indirect result of contact with winery wastewater. Under the given conditions, results obtained in this two seasons of the study suggest that irrigation using augmented winery wastewater does not affect grapevine performance or wine quality substantially. The major impact that was observed was an increase in wine pH and a decreasing trend in TTA. Both these parameters could be rectified by simply adding acid to the wines. Therefore, irrigation using augmented winery wastewater may be considered as a possible future alternative source for vineyard irrigation. It is, however, important to remember that some of the effects of wastewater irrigation may be cumulative and could possibly arise only after several years. Furthermore, different field conditions and cultivars may respond differently.
AFRIKAANSE OPSOMMING: Wingerd prestasie en wyngehalte word deur verskeie faktore beïnvloed waarvan twee van die belangrikste die beskikbaarheid en gehalte van besproeiingswater is. In relatiewe droë lande soos Suid Afrika is waterbesparing en die effektiewe benutting van water hulpbronne van uiterste belang. Die verwagte toename in temperatuur en afname in reënval in die toekoms as gevolg van klimaatsveranderinge plaasdieklem op op die belangrikheid van waterbesparing. Dit het navorsing om moontlike alternatiewe vorme van besproeiingswater te ontdek geïnspireer. Na aanleiding van hierdie faktore word daar toenemend gefokus op navorsing oor die moontlikheid om kelder afvalwater as alternatiewe bron van besproeiings water vir wingerde te benut. Kelder afvalwater bevat hoër konsentrasie van sekere elemente as water wat onder normale omstandighede gebruik word vir die besproeiing van wingerde, die belangrikste verskille was die vlakke van Na en K. Benewens die hoër konsentrasie van sekere elemente bevat kelder afvalwater ook groot populasies van mikroörganismes soos giste, melksuurbakterieë en asynsuurbakterieë, tipies geassosieerd met wynbereiding. Indien besproeiing met kelder afvalwater die opname van sekere elemente of die plant water status beϊnvloed, mag wingerd groei, sap en wyn samestelling beϊnvloed word. Daar benewens, indien die mikrobiese samestelling van die sap en wyn beϊnvloed word sal die samestelling en sensoriese gehalte van die wyn moontlik beϊnvloed word. Cabernet Sauvignon/99R wingerde, geleë in sanderige grond in die Breede Rivier Vallei, is onderwerp aan besproeiing met agt verskillende konsentrasies van verdunde kelder afvalwater, bykomend tot besproeiing met onbehandelde rivier water wat as kontrole gedien het. Hierdie studie is uitgevoer gedurende die 2010/11 en 2011/12 seisoene. Die teiken besproeiings konsentrasies is verkry deur kelder afvalwater met onbehandelde rivier water te verdun tot ‘n sekere chemiese suurstofbehoefte (CSB) konsentrasie bereik is. Die CSB is in hierdie studie ‘n direkte aanduiding van watergehalte, die twee was indirek eweredig tot mekaar. Die agt CSB konsentrasies waarteen die afvalwater besproei is wissel tussen 100 mg/L CSB en 3000 mg/L CSB. Die eerste doelwit van die studie was om te bepaal wat die effek van besproeiing met verdunde kelder afvalwater op wingerdprestasie, met spesifieke verwysing na vegetatiewe groei, korrelontwikkeling en korrelsamestelling is. Wingerd vegetatiewe en reproduktiewe groei, insluitende opbrengs, is op geen stadium tydens korrelontwikkeling tot en met oes beïnvloed nie. Die laai van suikers gedurende rypwording, sowel as verskuiwings in suurkonsentrasie, is nie deur besproeiing met kelder afvalwater beïnvloed nie. In die tweede seisoen is ‘n toename in sap pH waargeneem soos die CSB konsentrasie van die besproeiings water toegeneem het. Die element, ioon en swaar metaal samestelling van sap was nie beïnvloed deur besproeiing met afvalwater nie wat aandui dat daar geen opname was deur die wingerd nie. Die dikte, kleur en fenoliese samestelling van druifdoppe is ook nie beïnvloed nie. Die tweede doelwit van die studie was om te bepaal wat die effek van besproeiing met verdunde kelder afvalwater op wyn mikrobiese en chemiese samestelling, fermentasie effektiwiteit en wyn sensoriese eienskappe is. Die verskeie afvalwater besproeiings behandelings het geen effek op die natuurlike gis of bakterieë flora van die sap gehad nie. Die vermoë van die geïnokuleerde gis en melksuurbakterieë om hul afsonderlike fermentasie prosesse te voltooi is ook nie beïnvloed nie. Met die uitsondering van totale titreerbare suur (TTS) en pH, is die chemiese samestelling van wyne met betrekking tot basiese wyn parameters, kleur, fenole en tanniene nie beïnvloed nie. Soortgelyk aan sap is wyn fosfor en geselekteerde ioon samestelling nie geaffekteer nie. Die sensoriese karakteristieke was eenders vir wyne van alle behandelings. Die derde doelwit van die studie was om te bepaal wat die effek wat direkte kontak van kelder afvalwater met druiwekorrels op wyn sensoriese eienskappe het. Hierdie studie het gefokus op die oordrag van afgeure vanaf kelder afvalwater na die wyne sowel as die voorkoms van afgeure as ‘n reaksie op kontak met kelder afvalwater. Wyn kleur en algemene sensoriese eienskappe is nie geaffekteer deur kontak tussen druiwe en kelder afvalwater nie. Kelder afvalwater-geassosieerde afgeure en vlugtige suur was meer duidelik waarneembaar in wyne wat gemaak is van druiwe wat in kontak was met die meer gekonsentreerde afvalwater. Dit mag dus moontlik wees dat afgeure vanaf kelder afvalwater oorgedra word na wyne, of dat sekere afgeure gevorm word as ‘n direkte of indirekte reaksie op kontak met kelder afvalwater. Onder die gegewe toestande oor die twee jaar studie periode het resultate getoon dat besproeiing met verdunde kelder afvalwater nie wingerdprestasie en wyn gehalte aansienlik beïnvloed nie. Die grootste impak wat afvalwater besproeiing gehad het, was om ‘n toename in wyn pH en ‘n tendens tot afname in TTS te veroorsaak. Deur eenvoudig suur by die wyn te voeg kan albei hierdie probleme reg gestel word. Op grond van hierdie bevindings kan besproeiing met verdunde kelder afvalwater moontlik as toekomstige bron vir addisionele wingerdbesproeiing dien. Dit is egter belangrik om te onthou dat die effekte van besproeiing met kelder afvalwater mootlik kumulatief kan wees en dat probleme moontlik eers na etlike jare na vore kan kom. Ander kultivars en veldkondisies mag ook lei tot ander resultate.

Thesis (PhD(Agric))-- Stellenbosch University, 2014.
ENGLISH ABSTRACT: Brandy producers in South Africa can produce three categories of brandy, and within those categories, varies styles in order to cater for diverse consumer needs. Thus they have divergent opinions as to what comprises a good base wine and distillate for their individual end-product style in mind. Due to the fact that brandy is the largest locally produced spirit in South Africa, it is crucial to investigate the factors that influence the production of brandy as better understanding and control of these processes leads to the production of a brandy that is more consistent in quality and in style. The factors known to influence the quality of brandy are the grape cultivar, vinification techniques, distillation and the oak maturation process; however limited research has been done on the factors contributing to the style of brandies. Understanding and identifying the factors that contribute to the style of brandy, will allow for better control and manipulation of the process to ultimately produce a spirit product with a desired style classification. In order to do so, one must distinguish as to what differentiates (chemical and sensory analyses) the two most divergent styles of brandy (in this study referred to as class one and class five three-year barrel matured brandy). Over 104 three-year old barrel matured brandy samples were collected and analysed using GC-FID and HPLC analysis over a three year period. Of these samples, only 7 were classified as a class one three-year barrel matured brandy and 23 were found to be classified as class five three-year barrel matured brandy. The results obtained showed that the class one samples were found to contain a higher concentration of total higher alcohols, higher ratio of higher alcohols vs. esters, higher alcohols vs. acids and aldehydes vs. esters, but a lower level of total esters and acids. The class five samples contained a higher concentration of total esters, furans, lactones and acids, but a lower level of total higher alcohols and ratio of higher alcohols vs. esters. The factors investigated that possibly influence the style of brandy were: the base wine prior to distillation, yeast strain, fermentation temperature, condenser water temperature and barrel age. Results of the base wine analysed prior to distillation show that those samples that scored a sensory score of one could produce a class one three-year barrel matured brandy, and base wines that scored a sensory score of five would yield a class five three-year barrel matured brandy. Alchemy 1 yeast was found to produce elevated levels of total esters and could by default result in a class five three-year barrel matured brandy. Similarly if the wine was fermented at 24⁰C it would result in the increased production of higher alcohols and total acids and in-turn could yield a class one three-year barrel matured brandy. The results obtained show that the different condenser water temperatures do not necessarily influence the concentration of esters and higher alcohols. However, if a lower condenser water temperature (8⁰C) was employed, it could yield a class one barrel matured brandy sample. These distillates are associated with a higher concentration of total higher alcohols and even though they may be positively associated with higher levels of esters, the esters could be removed during the head fraction in the distillation process. The results also show that during the maturation process that the use of 18 year old barrels for the maturation of three-year barrel matured brandy samples could possibly produce a class one three-year barrel matured brandy and the use of new barrels could yield a class five three-year barrel matured brandy sample. It is recommended that analysing the base wine prior to distillation using GC-FID to identify the chemical composition is the most important step in determining the outcome of the style of brandy.
AFRIKAANSE OPSOMMING: Brandewyn produsente in Suid-Afrika kan drie kategorieë brandewyn produseer, en binne hierdie kategorieë sekere style om voorsiening te maak vir die diverse behoeftes van die mark, en dus het hulle uiteenlopende menings oor wat 'n goeie basis wyn en distillaat behels vir hul individuele eindproduk se spesifieke styl. As gevolg van die feit dat brandewyn die belangrikste spiritus produk is wat deur die Suid-Afrikaanse bevolking verbruik word, is dit noodsaaklik dat dié faktore wat die produksie van brandewyn beïenvloed ondersoek word om 'n beter begrip van, en beheer oor hierdie prosesse verkry kan. Dit sal lei tot die produksie van 'n brandewyn van konstante in qualitiet en in style. Die faktore wat bekend is om die gehalte van brandewyn te beïnvloed, is die druifkultivar, wynbereidingstegnieke, distillasie en die hout verouderings proses, maar daar is beperkte navorsing oor die faktore wat bydra tot die styl van n brandewyn. Om die faktore wat bydra tot die spesifieke styl van n brandewyn te identifiseer en te verstaan, kan dit lei tot 'n beter beheer en manipulasie van die prosess om uiteindelik n brandewyn met 'n gewenste styl te produseer. Ten einde dit te kan doen, moet 'n mens kan bepaal wat die twee uiterste style van brandewyn (wat in die studie sal bekend wees as klas een en klas vyf drie-jaar vat veroude brandewyn) van mekaar onderskei (chemiese en sensoriese analise). Meer as 104 drie-jaar vat verouderde brandewyn monsters is ingesamel en ontleed met behulp van GC-FID en HPLC analyliese oor 'n tydperk van drie jaar. Van die 104 monsters, is slegs 7 as 'n klas een drie-jaar vat verourde brandewyn geklassifiseer en 23 as klas vyf drie-jaar vat verourde brandewyn geklassifiseer. Die resultate het getoon dat die klas een monsters 'n hoër konsentrasie van die totale hoër alkohole, 'n hoër verhouding van hoër alkohole teenoor esters het, hoër alkohole teenoor sure en aldehiede teenoor esters, maar 'n laer vlak van totale esters en sure. Die klas vyf monsters het 'n hoër konsentrasie van die totale esters, furanen, laktone en sure, maar 'n laer vlak van totale hoer alkohol en verhouding van hoër alkohole teenoor esters. Die faktore wat ondersoek was wat moontlike ‘n invloed op die styl van brandewyn kon hê, was die basis wyn voor distillasie, die gisras, die fermentasie temperatuur, die kondensor water temperatuur en die vat ouderdom. Die ontledings van die basis wyn voor distillasie het gewys dat die monsters wat 'n sensorise telling van een behaal het, moontlik kan lei tot 'n klas een drie-jaar vat verouderde brandewyn, en basis wyne wat 'n sensorise telling van vyf gekry het weer ‘n klas vyf drie-jaar vat verouderde brandewyn sou oplewer. Alchemie 1 gis ras het ‘n verhoogde vlak van totale esters geproduseer wat tot 'n klas vyf drie-jaar vat verouder brandewyn gelei het As die basis wyn gefermenteer is teen 24⁰C sal dit lei tot die verhoogde produksie van hoër alkohole en totale sure wat 'n klas een drie-jaar vat verouderde brandewyn kan oplewer. Die resultate verkry, toon dat die verskillende kondensor water temperature nie noodwendig die konsentrasie van esters en hoër alkohole beïnvloed het nie, maar dit wil voorkom dat indien 'n laer kondensor water temperatuur (8⁰C) gebruik is, kan dit 'n klas een vat verouderde brandewyn oplewer. Dit hou verband met 'n hoër konsentrasie van die totale hoër alkohole en selfs al word die distillate positief geassosieer met hoër vlakke van esters, kan die esters verwyder word tydens die verwydering van die voorloop in die distillasie proses. Die resultate toon ook dat die gebruik van 18 jaar oue vate vir die veroudering van brandewyn moontlik 'n klas een drie-jaar vat verouderde brandewyn kan oplewer en die gebruik van nuwe vate kan 'n klas vyf drie-jaar vat verouderde brandewyn lewer. Dit word egter aanbeveel dat die basis wyn voor distillasie met GC-FID chemies ontleed word om die samestelling van die wyn te identifiseer Die resultate bly die beste aanduiding van die styl van die brandewyn.

The article deals with the topical issue of combating counterfeit food products, in particular wine-making. The main controllable indicators are given, based on the verification of which it is possible to assess the finished product authenticity, quality and safety. A steady increase in the counterfeiting alcoholic beverages level and ways of solving countering the counterfeit products release in the developing methodological base context a are noted. The finished product monitoring relevance in the domestic market is noted, and the analytical analysis methodology improvement based on it, as well as the updating of the tool base nomenclature.

The goals of the present research proposal were to elucidate the physiological and molecular basis of the regulation of stilbene metabolism in grape, against the background of (i) grape metabolic network behavior in response to drought and of (ii) varietal diversity. The specific objectives included the study of the physiology of the response of different grape cultivars to continuous WD; the characterization of the differences and commonalities of gene network topology associated with WD in berry skin across varieties; the study of the metabolic response of developing berries to continuous WD with specific attention to the stilbene compounds; the integration analysis of the omics data generated; the study of isolated drought-associated stress factors on the regulation of stilbene biosynthesis in plantaand in vitro. Background to the topic Grape quality has a complex relationship with water input. Regulated water deficit (WD) is known to improve wine grapes by reducing the vine growth (without affecting fruit yield) and boosting sugar content (Keller et al. 2008). On the other hand, irregular rainfall during the summer can lead to drought-associated damage of fruit developmental process and alter fruit metabolism (Downey et al., 2006; Tarara et al., 2008; Chalmers et al., 792). In areas undergoing desertification, WD is associated with high temperatures. This WD/high temperature synergism can limit the areas of grape cultivation and can damage yields and fruit quality. Grapes and wine are the major source of stilbenes in human nutrition, and multiple stilbene-derived compounds, including isomers, polymers and glycosylated forms, have also been characterized in grapes (Jeandet et al., 2002; Halls and Yu, 2008). Heterologous expression of stilbenesynthase (STS) in a variety of plants has led to an enhanced resistance to pathogens, but in others the association has not been proven (Kobayashi et al., 2000; Soleas et al., 1995). Tomato transgenic plants harboring a grape STS had increased levels of resveratrol, ascorbate, and glutathione at the expense of the anthocyanin pathways (Giovinazzo et al. 2005), further emphasizing the intermingled relation among secondary metabolic pathways. Stilbenes are are induced in green and fleshy parts of the berries by biotic and abiotic elicitors (Chong et al., 2009). As is the case for other classes of secondary metabolites, the biosynthesis of stilbenes is not very well understood, but it is known to be under tight spatial and temporal control, which limits the availability of these compounds from plant sources. Only very few studies have attempted to analyze the effects of different environmental components on stilbene accumulation (Jeandet et al., 1995; Martinez-Ortega et al., 2000). Targeted analyses have generally shown higher levels of resveratrol in the grape skin (induced), in seeded varieties, in varieties of wine grapes, and in dark-skinned varieties (Gatto et al., 2008; summarized by Bavaresco et al., 2009). Yet, the effect of the grape variety and the rootstock on stilbene metabolism has not yet been thoroughly investigated (Bavaresco et al., 2009). The study identified a link between vine hydraulic behavior and physiology of stress with the leaf metabolism, which the PIs believe can eventually lead to the modifications identified in the developing berries that interested the polyphenol metabolism and its regulation during development and under stress. Implications are discussed below.

The Montney Formation is a highly productive hydrocarbon reservoir with significant reserves of hydrocarbon gases and liquids making it of great economic importance to Canada. However, high concentrations of hydrogen sulfide (H2S) have been encountered during exploration and development that have detrimental effects on environmental, health, and economics of production. H2S is a highly toxic and corrosive gas and therefore it is essential to understand the distribution of H2S within the basin in order to enhance identification of areas with a high risk of encountering elevated H2S concentrations in order to mitigate against potential negative impacts. Gas composition data from Montney wells is routinely collected by operators for submission to provincial regulators and is publicly available. We have combined data from Alberta (AB) and British Columbia (BC) to create a basin-wide database of Montney H2S concentrations. We then used an iterative quality control and quality assurance process to produce a dataset that best represents gas composition in reservoir fluids. This included: 1) designating gas source formation based on directional surveys using a newly developed basin-wide 3D model incorporating AGS's Montney model of Alberta with a model in BC, which removes errors associated with reported formations; 2) removed injection and disposal wells; 3) assessed wells with the 50 highest H2S concentrations to determine if gas composition data is accurate and reflective of reservoir fluid chemistry; and 4) evaluated spatially isolated extreme values to ensure data accuracy and prevent isolated highs from negatively impacting data interpolation. The resulting dataset was then used to calculate statistics for each x, y location to input into the interpolation process. Three interpolations were constructed based on the associated phase classification: H2S in gas, H2S in liquid (C7+), and aqueous H2S. We used Empirical Bayesian Kriging interpolation to generate H2S distribution maps along with a series of model uncertainty maps. These interpolations illustrate that H2S is heterogeneously distributed across the Montney basin. In general, higher concentrations are found in AB compared with BC with the highest concentrations in the Grande Prairie region along with several other isolated region in the southeastern portion of the basin. The interpolations of H2S associated with different phases show broad similarities. Future mapping research will focus on subdividing intra-Montney sub-members plus under- and overlying strata to further our understanding of the role migration plays in H2S distribution within the Montney basin.

Evidence on the effectiveness of travel measures to prevent or slow the spread of Covid-19 and guidance on how and when to apply these measures is limited and the results are mixed. Given the social and economic disruptions that these measures can have, and their potential adverse effects on preventing the spread of the disease, WHO among others have cautioned implementing measures that are not supported by robust evidence. The scope of the search for this report was broad, covering all reported international travel restrictions to contain or slow the spread of Covid-19 and without geographical limitations. The results are therefore more general than restriction- or country-specific and more targeted studies may be omitted from the search due to these wide search parameters. There is general agreement across the literature that some form of travel restriction in the early stages of a disease or variant spread can lead to a slowing of the rate of infections in countries yet to be affected. The majority of studies conducted on travel restrictions adopt a modelling approach, and a systematic review conducted in December 2020 concluded that the quality of observational studies was low to very low (Bou-Karroum et al., 2021). Determining the specific effects of different travel measures is difficult as many studies examine the effects of combined measures. Few studies separate different types of restrictions and much of the modelling on international transmission rates uses data on the movements of people as a proxy for travel restrictions, therefore limiting the ability to observe how measures were implemented except for the timing of measures at different points in the pandemic. Limited country-level evidence was identified for this report and few global studies examine contextual factors that might affect the effectiveness of travel restriction measures. A targeted search for evidence on the effects of travel restrictions on different variants of Covid-19 did not reveal any studies making this distinction.

As a student undertaking a Longitudinal Integrated Clerkship (LIC)1 based in a GP practice in a rural community in the North of Scotland, I have been lucky to be given responsibility and my own clinic lists. Every day I conduct consultations that change my practice: the challenge of clinically applying the theory I have studied, controlling a consultation and efficiently exploring a patient's problems, empathising with and empowering them to play a part in their own care2 – and most difficult I feel – dealing with the vast amount of uncertainty that medicine, and particularly primary care, presents to both clinician and patient. I initially consulted with a lady in her 60s who attended with her husband, complaining of severe lower back pain who was very difficult to assess due to her pain level. Her husband was understandably concerned about the degree of pain she was in. After assessment and discussion with one of the GPs, we agreed some pain relief and a physio assessment in the next few days would be a practical plan. The patient had one red flag, some leg weakness and numbness, which was her ‘normal’ on account of her multiple sclerosis. At the physio assessment a few days later, the physio felt things were worse and some urgent bloods were ordered, unfortunately finding raised cancer and inflammatory markers. A CT scan of the lung found widespread cancer, a later CT of the head after some developing some acute confusion found brain metastases, and a week and a half after presenting to me, the patient sadly died in hospital. While that was all impactful enough on me, it was the follow-up appointment with the husband who attended on the last triage slot of the evening two weeks later that I found completely altered my understanding of grief and the mourning of a loved one. The husband had asked to speak to a Andrew MacFarlane Year 3 ScotGEM Medical Student 2 doctor just to talk about what had happened to his wife. The GP decided that it would be better if he came into the practice - strictly he probably should have been consulted with over the phone due to coronavirus restrictions - but he was asked what he would prefer and he opted to come in. I sat in on the consultation, I had been helping with any examinations the triage doctor needed and I recognised that this was the husband of the lady I had seen a few weeks earlier. He came in and sat down, head lowered, hands fiddling with the zip on his jacket, trying to find what to say. The GP sat, turned so that they were opposite each other with no desk between them - I was seated off to the side, an onlooker, but acknowledged by the patient with a kind nod when he entered the room. The GP asked gently, “How are you doing?” and roughly 30 seconds passed (a long time in a conversation) before the patient spoke. “I just really miss her…” he whispered with great effort, “I don’t understand how this all happened.” Over the next 45 minutes, he spoke about his wife, how much pain she had been in, the rapid deterioration he witnessed, the cancer being found, and cruelly how she had passed away after he had gone home to get some rest after being by her bedside all day in the hospital. He talked about how they had met, how much he missed her, how empty the house felt without her, and asking himself and us how he was meant to move forward with his life. He had a lot of questions for us, and for himself. Had we missed anything – had he missed anything? The GP really just listened for almost the whole consultation, speaking to him gently, reassuring him that this wasn’t his or anyone’s fault. She stated that this was an awful time for him and that what he was feeling was entirely normal and something we will all universally go through. She emphasised that while it wasn’t helpful at the moment, that things would get better over time.3 He was really glad I was there – having shared a consultation with his wife and I – he thanked me emphatically even though I felt like I hadn’t really helped at all. After some tears, frequent moments of silence and a lot of questions, he left having gotten a lot off his chest. “You just have to listen to people, be there for them as they go through things, and answer their questions as best you can” urged my GP as we discussed the case when the patient left. Almost all family caregivers contact their GP with regards to grief and this consultation really made me realise how important an aspect of my practice it will be in the future.4 It has also made me reflect on the emphasis on undergraduate teaching around ‘breaking bad news’ to patients, but nothing taught about when patients are in the process of grieving further down the line.5 The skill Andrew MacFarlane Year 3 ScotGEM Medical Student 3 required to manage a grieving patient is not one limited to general practice. Patients may grieve the loss of function from acute trauma through to chronic illness in all specialties of medicine - in addition to ‘traditional’ grief from loss of family or friends.6 There wasn’t anything ‘medical’ in the consultation, but I came away from it with a real sense of purpose as to why this career is such a privilege. We look after patients so they can spend as much quality time as they are given with their loved ones, and their loved ones are the ones we care for after they are gone. We as doctors are the constant, and we have to meet patients with compassion at their most difficult times – because it is as much a part of the job as the knowledge and the science – and it is the part of us that patients will remember long after they leave our clinic room. Word Count: 993 words References 1. ScotGEM MBChB - Subjects - University of St Andrews [Internet]. [cited 2021 Mar 27]. Available from: https://www.st-andrews.ac.uk/subjects/medicine/scotgem-mbchb/ 2. Shared decision making in realistic medicine: what works - gov.scot [Internet]. [cited 2021 Mar 27]. Available from: https://www.gov.scot/publications/works-support-promote-shared-decisionmaking-synthesis-recent-evidence/pages/1/ 3. Ghesquiere AR, Patel SR, Kaplan DB, Bruce ML. Primary care providers’ bereavement care practices: Recommendations for research directions. Int J Geriatr Psychiatry. 2014 Dec;29(12):1221–9. 4. Nielsen MK, Christensen K, Neergaard MA, Bidstrup PE, Guldin M-B. Grief symptoms and primary care use: a prospective study of family caregivers. BJGP Open [Internet]. 2020 Aug 1 [cited 2021 Mar 27];4(3). Available from: https://bjgpopen.org/content/4/3/bjgpopen20X101063 5. O’Connor M, Breen LJ. General Practitioners’ experiences of bereavement care and their educational support needs: a qualitative study. BMC Medical Education. 2014 Mar 27;14(1):59. 6. Sikstrom L, Saikaly R, Ferguson G, Mosher PJ, Bonato S, Soklaridis S. Being there: A scoping review of grief support training in medical education. PLOS ONE. 2019 Nov 27;14(11):e0224325.

Cheese, a traditional food incorporated into many cuisines, is used as an ingredient in cooking or consumed directly as an appetizer or dessert, often with wine or other suitable beverages. Great numbers of cheese varieties are produced, reflecting in part the versatility of the microorganisms used in cheese-making that this FAQ report will describe. Cheese is one of the few foods we eat that contains extraordinarily high numbers of living, metabolizing microbes, leading some participants to say, “Cheese is alive!” The broad groups of cheese-making microbes include many varieties of bacteria, yeast, and filamentous fungi (molds). This report focuses on the microbiology of “natural” cheeses, those made directly from milk, including hard and soft varieties such as Cheddar, Mozzarella, and Camembert. Pasteurized process cheese, the other broad category of cheese, is made by blending natural cheeses with emulsifying agents, preservatives, thickeners, flavorings, and seasonings. “American cheese” is perhaps the classic example of a process cheese, notwithstanding recent examples of American artisanal cheese-making and changing tastes among consumers of those cheeses.