Thesis (MScAgric)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: In an attempt to reduce the pH of juice and wine, different fertiliser applications and canopy management practices were evaluated in a field trial. Fertiliser treatments consisted of no, CaS04, Ca(OH)2, and MgS04 fertilisation. Canopy management was as follows: suckering (leaving only two shoots per bearer), tipping, vertical shoot positioning and removal of lateral shoots and yellow leaves in the bunch zone (Canopy 1); suckering (leaving three shoots per bearer), vertical shoot positioning as well as topping (Canopy 2); vertical shoot positioning and topping (Canopy 3). The field trial was conducted in the Paardeberg region on the farms Meerlus and Kersfontein. The vineyard at Meerlus was Cabernet franc/R99 with a high canopy density and a good root distribution, established on a sandy loam soil of granite origin, with a low subsoil pH and a high K content. The vineyard at Kersfontein was Cabemet Sauvignon/101-14 Mgt with a lower canopy density and a less extensive root distribution, also established on a sandy loam soil of granite origin, but with a low top- and subsoil pH and a higher K content. Fertilisation had no significant influence on the K content of juice and wine. Fertilisation with Ca and Mg reduced the pH of juice significantly in the case of Meerlus. In contrast, Mg fertilisation increased the pH of juice significantly at Kersfontein. Lastly, fertilisation had no significant effect on the pH of the wine. The K content of the juice at Meerlus was significantly reduced by Canopy 3 in comparison with Canopy 1 and 2. However, in contrast with Canopy 1 and 3, Canopy 2 significantly increased the pH of juice at Meerlus. The K content of the juice at Kersfontein was significantly reduced by Canopy 1, compared to Canopy 2 and 3, with no significant effect on the pH of the juice. Canopy management had no significant effect on wine pH. It appears to be possible to reduce the pH of juice in the case of Cabernet franc/99R, situated on granite soils, by means of Ca and Mg fertilisation. Because Ca(OH)2 and MgS04 fertilisation increased the maturity of Cabernet Sauvignon/101-14 Mgt grapes, it was impossible to evaluate the effect of fertilisation on the pH of juice at Kersfontein. The general phenomenon that a high canopy density results in a high pH of juice and wine, was not observed in this field trial. The possible reasons for this were the low canopy density of the control plots, as well as the difference in maturity between canopy management treatments. / AFRIKAANSE OPSOMMING: In 'n poging om die pH van sap en wyn te verlaag, is die effek van verskillende bemesting- en lowerbestuursfaktore in 'n veldproef geêvalueer. Bemesting het bestaan uit geen, CaS04, Ca(OH)2 en MgS04 toediennings. Lowerbestuur was: suier tot twee lote per draer, tip, vertikale lootposisionering, verwydering van sylote en geel blare in trossone (Lower 1); suier tot drie lote per draer, top en vertikale lootposisionering (Lower 2); top en vertikale lootposisionering met geen suier nie (Lower 3). Die veldproef is op twee plase nl. Meerlus en Kersfontein, in die Paardeberg omgewing uitgevoer. Die wingerd by Meerlus was Cabernet franc/R99 met 'n hoë lowerdigtheid en goeie wortelverspreiding, wat op 'n sandleemgrond van graniet oorsprong met In lae ondergrond-pH en hoë K-inhoud gevestig is. Die wingerd by Kersfontein het bestaan uit Cabernet Sauvignon/101-14 Mgt met 'n laer lowerdigtheid en swakker wortelverspreiding, wat op In sandleemgrond van graniet oorsprong met In deurgaans lae grond-pH en baie hoë K-inhoud gevestig is. Bemesting het geen betekenisvolle invloed op die K-inhoud van sap en wyn gehad nie. By Meerlus het Ca- en Mg-bemesting egter die pH van sap betekenisvol verlaag. In teenstelling hiermee het Mg-bemesting die sap-ph by Kersfontein betekenisvol verhoog. Bemesting het verder geen betekenisvolle invloed op die pH van wyn gehad nie. Lower 3 het die K-inhoud van sap by Meerlus betekenisvol verlaag in vergelyking met Lower 1 en Lower 2. By Kersfontein was die K-inhoud van sap by Lower 1 betekenisvollaer as by Lower 2 en Lower 3. Teenoor Lower 1 en Lower 3 het Lower 2 'n betekenisvol hoër sap-pH by Meerlus tot gevolg gehad. Lowerbehandelings het egter geen betekenisvolle invloed op die pH van wyn gehad nie. Die moontlikheid bestaan dus om die sap-pH van Cabernet franc/R99 op granietgrond betekenisvol m.b.v. Ca- en Mg-bemesting te verlaag. Aangesien Ca(OH)2- en MgS04- bemesting die rypheidsgraad van Cabernet Sauvignon/101-14 Mgt se druiwe betekenisvol verhoog het, was dit onmoontlik om die effek van bemesting op sap-pH by Kersfontein te evalueer. Die algemene verskynsel dat 'n hoë lowerdigtheid tot hoë pH's in sap en wyn lei, is nie in die proef ondervind nie. Die lae lowerdigtheid van die kontrole persele en die verskil in rypheidsgraad tussen lowerbehandelings kan moontlik as rede hiervoor aangevoer word.

Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The production of wine is a complex process, which involves the conversion of sugar in grape must to ethanol, carbon dioxide and other byproducts. The principal organism in winemaking is yeast, of which Saccharomyces cerevisiae is the most important due to its ability to survive winemaking conditions, its GRAS (Generally Regarded As Safe) status and the favourable flavours it imparts during the winemaking process. However, due to the demands of the consumer and the emergence of sophisticated wine markets, a demand is developing for specialised yeast strains with enhanced and new oenological properties. For these reasons, research into the contribution of wine yeast to the aroma bouquet as well the influence of wine or brandy maturation in wood on the aroma bouquet is important for consumer demands to be met. The fruity aroma of wine is associated with esters, which are produced during the alcoholic fermentation by yeast. Important acetate esters in wine and brandy are ethyl acetate, which has a fruity, solvent-like aroma, and isoamyl acetate, which has a banana-like aroma. These esters are produced through the action of acetyltransferases (AATases), which catalyse the reaction between a higher alcohol and acyl Coenzyme A. Esters are mainly a product of alcoholic fermentation. However, their concentration changes during wood maturation and it has been found that the concentration of acetate esters can increase during the maturation period. In this study, the aim was to investigate the influence of AATase I and AATase II, which are encoded by the ATF1 and ATF2 genes respectively, on the aroma bouquet of wine and brandy. Therefore, the first objective of this study was to clone the ATF2 gene from a commercial wine yeast strain and to overexpress this gene in a commercial wine yeast strain and in a wine yeast strain that already has the A TF1 gene overexpressed. Disruption cassettes were also designed in order to disrupt the ATF1 and ATF2 genes in a commercial wine yeast strain. The resultant recombinant wine yeast strains were used for the production of wine and brandy. GC analyses and tasting trials were conducted to determine the effect of the overexpression or disruption of these genes on the aroma bouquet of wine. The results obtained indicated that there are differences in the aroma bouquet of wine and brandy when changes are made in gene expression. The results indicated that the A TF1 gene plays a large role in the production of ethyl and isoamyl acetate. When this gene was overexpressed, the level of ethyl acetate was 5.6-fold more than that of the control and the level of isoamyl acetate was 3.5-fold higher than that of the control. However, no increase in ethyl acetate or isoamyl acetate was observed when the A TF2 gene was overexpressed. An increase in 2-phenylethyl acetate and diethyl succinate was observed in brandy, although there was a decrease in total ester concentration. A decrease in acetic acid was also observed in the brandy produced, which could be an indication of ester production. Similarly, no increase in ethyl acetate or isoamyl acetate was observed in the wine or brandy produced when both the ATF1 and ATF2 genes were overexpressed in a single yeast. Once again, a marked decrease was observed in acetic acid concentration in both the wine and brandy. In conclusion, it is clear that changes in gene expression can change the aroma profile of wine or brandy. However, the role of the ATF2 gene still remains unclear and further studies are needed to clarify its role in yeast. Future studies involving the effect of wood maturation on ester concentration will also be of importance, so that the winemaker or distiller can make a product that suits the ever-changing market. / AFRIKAANSE OPSOMMING: Die produksie van wyn is 'n komplekse proses wat die omskakeling van die suiker in mos tot etanol, koolstofdioksied en ander byprodukte tot gevolg het. Die hooforganisme betrokke in die wynmaakproses is gis, waarvan Saccharomyces cerevisiae as een van die belangrikste geag word as gevolg van die vermoë daarvan om onder die wynfermentasietoestande te kan oorleef, die "GRAS"-status (Generally Regarded As Safe) daarvan en die invloed wat dit op die aroma van die uiteindelike produk het weens die werking daarvan gedurende alkoholiese fermentasie. Die behoefte aan wyn met nuwe, verbeterde eienskappe het die vraag na meer gespesialiseerde gisrasse deur beide die verbruiker en nuwe wynmarkte gedurende die afgelope paar jaar drasties laat toeneem. Dit is om dié redes dat navorsing oor die bydrae van wyngis en houtveroudering tot die aroma van beide wyn en brandewyn so belangrik geag word. Die vrugtige aroma van wyn word geassosieer met die esters wat gedurende die alkoholiese fermentasie deur gis gevorm word. Die belangrikste asetaatesters in wyn en brandewyn is etielasetaat, wat vir 'n oplosmiddelagtige, vrugtige aroma bekend is, en isoamielasetaat, wat 'n piesangaroma veroorsaak. Die esters word geproduseer deur die werking van asetieltransferases (AATases), wat as katalis in die reaksie tussen 'n hoër alkohol en asetiel-Ko-ensiem A optree. Alhoewel esters hoofsaaklik 'n produk van alkoholiese fermentasie is, wissel die konsentrasie daarvan gedurende houtveroudering. Daar is gevind dat die konsentrasie van die asetaatesters gedurende die verouderingsproses kan verhoog. Die studie het ten doelom die invloed van AATase I en AATase II, wat onderskeidelik deur die ATF1- en ATF2-gene geënkodeer word, op die aroma van wyn en brandewyn te ondersoek. Die eerste doelwit van die studie was vervolgens om die ATF2-geen vanaf 'n kommersiële wyngisras te kloneer en dit daarna te ooruitdruk in 'n kommersiële wyngisras, asook die geen te ooruitdruk in 'n kommersiële wyngisras wat reeds die ATF1-geen ooruitdruk. Disrupsiekassette is ook vir die disrupsie van die ATF1- en ATF2-gene in 'n kommersiële wyngisras ontwerp. Die rekombinante wyngisrasse wat gedurnde die studie gemaak is, is vir die produksie van wyn en brandewyn gebruik. Gas chromatografise-ontledings en sensoriese evaluerings is ook op die wyn en brandewyn uitgevoer. Die resultate van die studie het bewys dat daar wel veranderings plaasvind wanneer 'n verandering in geenuitdrukking gemaak is. Die resultate het weereens bevestig dat die ATF1-geen 'n belangrike rol in die produksie van etiel- en isoamielasetaat speel. Wanneer die ATF1-geen ooruitgedruk is, is die etielasetaatproduksie 5.6 keer meer en die isoamielasetaatproduksie 3.5 keer meer as in die kontrole. Die ooruitdrukking van die ATF2-geen het geen verhoging in etielasetaat of isoamielasetaat of in totale esters in die wyn getoon nie, alhoewel die ras 2.7 keer meer diëtielsuksinaat geproduseer het. In die brandewyn wat geproduseer is met die gisras waarin ATF2 ooruitgedruk is, was daar wel 'n verlaging in die asynsuur, wat 'n aanduiding van estervorming kan wees, alhoewel die totale esters wat geproduseer is minder was as in die kontrole. 'n Verhoging in diëtielsuksinaat en 2-fenielasetaat is ook gevind. Daar is geen verhoging in etiel- of isoamielasetaat getoon wanneer die ATF1- en ATF2-geen saam ooruitgedruk is nie. Die ras het minder totale sure in wyn en brandewyn geproduseer en ook geen verhoging in totale esters getoon nie. Uit die resultate is dit duidelik dat veranderings in geenuitdrukking 'n verandering in die aromaprofiel van wyn en brandewyn kan veroorsaak. Die rol van dié A TF2-geen is nog steeds onduidelik en verdere studies sal moet plaasvind om die rol van die geen te verduidelik. Studies wat konsentreer op die invloed van houtveroudering op esterkonsentrasie is ook belangrik vir die toekoms, want dit sal die wyn- of brandewynmaker meer beheer oor die uiteindelike produk gee en daardeur die wyn- of brandewynmaker help om 'n produk te vervaardig wat sy mark bevredig.

Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: No single chemical constituent can be accredited with giving wine and brandy their overall aroma and flavour. The aroma and flavour of wine and brandy are rather attributed to a number of chemical constituents reacting together and it is these reactions that give the beverage its character. Certain chemicals within wine and brandy do, however, make larger contributions to the flavour. These include the esters, terpenes and volatile acids, although others also exist. Esters are a large group of volatile compounds with variable aroma and flavour characteristics, including banana-like (isoamyl acetate), apple-like (ethyl caproate) and chemical/solvent-like (ethyl acetate). Esters are produced as secondary metabolites during the conversion of sugar to ethanol and are formed when an alcohol binds with a fatty acid. Chemically, ester metabolism is well documented and understood; however, much work still needs to be done on a genetic level. The yeast strain used during fermentation is one of the most important factors contributing to the type and quantity of esters produced. This is due to differences in genetic makeup. The metabolism of esters is controlled largely on a genetic level, with numerous genes being involved. The alcohol acetyltransferase genes are involved in ester anabolism, whilst esterase genes are involved in ester catabolism. Esterases have a negative effect on the overall level of esters within an alcoholic beverage, as they are capable of reducing the number of esters and are thus capable of altering the beverage's aroma and flavour profile. The IAH1 and the TIP1 gene products are believed to encode for two such esterases. The objective of this study was to investigate the contribution of the IAH1 and TIP1 genes to the level of esters in both wine and brandy. This was accomplished by using two approaches. Firstly, the above genes were disrupted using a polymerise chain reaction (PCR)-generated disruption cassette homologous to either the IAH1 or the TIP1 gene. These cassettes were integrated into the industrial wine yeast, Saccharomyces cerevisiae strain VIN13. The integrations were verified by Southern blot analysis to produce yeasts VIN13-~IAH1 and VIN13-~TIP1; however, only a single copy of each was disrupted. Secondly, the IAH1 and the TIP1 genes were cloned from S. cerevisiae using PCR into plasmid pj between the phosphoglycerate kinase gene (PGK1) promoter and terminator, producing plasmids pJ-IOE1 and pJ-TOE1. The PGK1 promoter has previously been shown to constitutively express genes at high levels. These new constructs were then used as template for PCR to produce two overexpression cassettes, one for IAH1 and the other for TlP1. These cassettes were integrated into S. cerevisiae VIN13 and verified by Southern blot analysis to produce strains VIN13-IOE1 and VIN13-TOE1. The above yeast strains including VIN13 were used for the production of wines and base wines from Colombard must. Reverse-transcriptase (RT-PCR) confirmed that the VIN13-IOE1 and VIN13-TOE1 strains overexpressed the appropriate gene at a higher level than the control VIN13 strain. The VIN13-AIAH1 disrupted strain showed no difference in expression level to that of the control strain, whilst VIN13-ATIP1 showed lower levels of expression than that of the control strain. VIN13-IOE1 behaved as expected, with a decrease of between 30% and 60% in the total ester level in the wine and base wine respectively, a 30% decrease in the total acid level and no change in the higher alcohol level. The VIN13-AIAH1 strain showed no difference to the control wine, most likely as this strain still expressed the IAH1 gene at levels consistent with the control strain. VIN13-TOE1 behaved in an unexpected manner - instead of hydrolysing esters, it appeared to produce them. This increase in the total ester level was most noticeable during distillation, when a 20% increase took place. Another unexpected occurrence was a large decline in the total acid level, with acetic acid being the most significant contributor, decreasing by up to 78%. This is a very favourable finding, as acetic acid is a known spoilage molecule and is a cause of sluggish/stuck fermentations. VIN13-ATIP1 behaved in an opposite manner to VIN13-TOE1, with higher total acid levels and slightly decreased total ester levels, especially during distillation. Neither affected the total higher alcohol levels. Sensorially, the only significant difference in the wine samples was for the fruity flavour. A panel of judges distinguished that VIN13-TOE1 was fruitier than the other wines, with VIN13-ATIP1 being the least fruity. This study again proves the significant impact that a single gene can have on the chemical makeup of wine and brandy. The relatively simple genetic alteration of an organism can drastically change and improve not only the organoleptic properties of the organism, but its viability as well. These alterations can produce more favourable organisms with more desirable characteristics for the fermenting beverage industry to produce products of higher quality and better suitability. / AFRIKAANSE OPSOMMING: Geen chemiese komponent kan uitgesonderword as die produseerder van aroma en geur in wyn of brandewyn nie. Die aroma en geur van wyn en brandewyn word eerder toegeskryf aan die interaksie tussen 'n groot aantal chemiese komponente om aan die drank sy karakter te gee. Enkele van hierdie chemiese komponente sluit in esters, terpene en vlugtige sure, om maar 'n paar te noem. Esters is "n groot groep van vlugtige verbindings wat beskik oor 'n verskeidenheid van aroma- en geurkenmerke, soos piesangagtig (isoamielasetaat), appelagtig (etielkaproaat) en chemies/oplosmiddelagtig (etielasetaat). Esters word as sekondêre metaboliete geproduseer wanneer suikers na etanolomgeskakel word en word gevorm wanneer "n alkohol met "n vetsuur verbind. Estermetabolisme is chemies goed beskryf en verstaan, maar op "n genetiese vlak is daar nog heelwat aspekte wat nagevors moet word. Die gisras betrokke gedurende fermentasie word beskou as een van die grootse bydraes tot die tipe en die hoeveelheid esters wat geproduseer word. Dit word toegeskryf aan verskille in die genetiese saamestelling van die gisras. Ester metabolisme word grootliks deur genetiese faktore beheer en verskeie gene is betrokke. Dit is hoofsaaklik die alkoholasetieltransferasegene wat vir esterkatabolisme verantwoordelik is, terwyl die esterasegene vir esteranabolisme verantwoordelik is. Esterases het 'n negatiewe effek op die totale estervlak binne alkoholiese dranke deurdat hulle in staat is om die aantal esters drasties te verminder en sodoende die drank se aroma- en geurprofiel te verander. Daar is voorgestel dat die IAH1- en die TlP1-geen produkte is wat vir twee sulke esterases kodeer. Die doel van hierdie studie was om die IAH1- en die TIP1-gene se bydrae tot die totale estervlak in wyn en brandewyn te ondersoek. Dit is deur twee benaderings uitgevoer. Eerstens is die bogenoemde gene d.m.V. disrupsiekassette wat homoloog aan die IAH1- of die TlP1-gene was, uitgeslaan. Die disrupsiekassette is deur die polimerasekettingreaksie (PKR) geproduseer. Hierdie kassette is in die industriële wyngis, Saccharomyces cerevisiae VIN13, geïntegreer. Die integrasies is deur Southernkladanalise bevestig en het die giste VIN13-~IAH1 en VIN13-~TIP1 gelewer. Net 'n enkele kopie van elke geen is egter uitgeslaan. Tweedens is die IAH1- en TIP1-gene d.m.V. PKR vanaf S. cerevisiae binne in plasmied pJ gekloneer, tussen die fosfogliseraatkinasegeen (PGK1) se promotor en termineerder, om plasmiede pJ-IOE1 en pJ-TOE1 te produseer. Die PGK1-promotor is al tevore geïdentifiseer as "n hoë-vlak konstitutiewe uitdrukker van gene. Hierdie twee nuwe konstrukte het vervolgens gedien as templaat vir PKR om twee ooruitdrukkingskassette, een vir IAH1 en die ander vir TIP1, te produseer. Hierdie kassette is in S. cerevisiae VIN13 geïntegreer en bevestig deur Southernkladanalise. Hierdie integrasies het die giste VIN13-IOE1 en VIN13-TOE1 geproduseer. All die nuwe gisrasse, tesame met VIN13, is gebruik vir die produksie van wyne sowel as rebatwyne vanaf Colombard-mos. Omgekeerde-transkriptase polimerasekettingreaksie (OT-PKR) het bewys dat die VIN13-IOE1 en VIN13-TOE1 rasse die geskikte geen ooruitgedruk het, met hoêr vlakke as van die kontrole VIN13-ras. Dit het ook aangedui dat die VIN13-i\IAH1-ras, waarvan die geen uitgeslaan was, geen verskil in uitdrukking gehad het in vergelyking met die kontroleras nie, terwyl VIN13-i\TIP1 'n lae uitdrukkingsvlak getoon het. VIN13-IOE1 het teen verwagting opgetree, met 'n afname van tussen 30% en 60% in die totale estervlak in beide die wyne en rebatwyne. 'n Afname van 30% in die totale suurvlak, asook geen waarneembare verskil in die hoêr alkoholvlak, in vergelyking met die kontroleras, is ook opgemerk. Die VIN13-i\IAH1-ras het glad nie van die kontroleras verskil nie, heel waarskynlik omdat hierdie ras die IAH1-geen teen dieselfde vlak as die kontroleras kon uitdruk. Die VIN13-TOE1-ras het teen verwagting opgetree deurdat dit esters geproduseer het i.p.v. om esters te hidroliseer. Hierdie toename in die totale estervlak is die meeste waarneembaar tydens distillasie, met tot 'n 20% toename. Nog 'n onverwagte effek was die groot afname in die totale suurvlak. met asynsuur wat die betekenisvolste bydrae gelewer het deurdat dit 'n afname van tot 78% getoon het. Hierdie bevinding is baie voordelig, aangesien asynsuur, 'n bekende bederfmolekuul, veral vir slepende/gestaakte fermentasies verantwoordelik is. VIN13-i\TIP1 het op die teenoorgestelde wyse opgetree as VIN13-TOE1, met 'n hoêr totale suurvlak en 'n klein afname in die totale estervlak. Weereens is dit meer gedurende distillasie waargeneem. Beide rasse het egter geen effek op die hoêr alkoholvlak gehad nie. Die proepaneel het, met betrekking tot die vrugtige geur, een betekenisvolle geurverskil tussen die wyne gevind. VIN13-TOE1 was meer vrugtig as al die ander wyne en VIN13-i\TIP1 was die minste vrugtig. Die studie het weereens bewys dat 'n enkele geen 'n betekenisvolle effek op die chemiese samestelling van wyn en brandewyn kan hê. Die relatief eenvoudige genetiese verandering van 'n organisme kan die organoleptiese eienskappe asook die lewensvatbaarheid van "n organisme, drasties verander en verbeter.

Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The presence and growth of lactic acid bacteria (LAB) in wine and their influence on wine quality has received much attention in recent years. Lactic acid bacteria are responsible for conducting malolactic fermentation (MLF) in wine. The benefits associated with malolactic fermentation in terms of deacidification of wine and the contribution to wine flavour and complexity have also recently been the topic of research. It is impossible to describe malolactic fermentation as distinctly desirable or undesirable in terms of its influence on the final quality of wine. The benefits and disadvantages are dependent upon viticultural region, grape variety, wine composition, winemaking techniques and the style and objectives of the winemaker. Brandy production is a multi-stage process in which base wine production, distillation technique and wood maturation all have a large influence on the final chemical profile and organoleptic quality of the brandy. The volatile composition of the base wine, which basically undergoes a concentration process during the subsequent double distillation phase, is critical in determining the aroma and flavour quality of the final brandy product. Thus, the brandy is only as good as the base wine it is distilled from. The aims of this study were to determine the effect of lactic acid bacteria and spontaneous malolactic fermentation on the quality of brandy base wine and the resulting distillate, and to determine which LAB species had been responsible for the occurrence of spontaneous MLF. This study showed that LAB are present at high numbers and are able to conduct spontaneous MLF of brandy base wines. It was shown that the incidence of spontaneous MLF varied from year to year. In 1998, 50% of the commercially produced base wines had undergone partial MLF prior to distillation. In 1999 and 2000 respectively, 34% and 45% of the commercial base wines had undergone partial MLF prior to distillation. The occurrence of spontaneous MLF had an influence on the chemical composition and the sensory quality of the base wine and distillate. There was an increase in the concentrations of ethyl lactate, acetic acid and diethyl succinate in samples that had undergone MLF. There was also a decrease in the concentrations of esters, such as iso-amyl acetate, ethyl acetate, ethyl caproate, hexyl acetate and 2-phenethyl acetate in these same samples. Sensory evaluation of the base wines and distillates demonstrated that samples that had undergone MLF differed significantly from samples that had not undergone MLF. It was also shown that distillates that had not undergone MLF had a slightly better aroma profile than those that had. Sweet aromas, like chocolate and caramel, as well as negative aromas, like chemical or solvent, were more prominent in brandy distillates that had undergone MLF. Herbaceous and fruity aromas were more intense in distillates not having undergone MLF. Fifty-four strains, all Gram-positive and catalase negative, were isolated at different stages of brandy production. Seven strains were isolated from the grape juice, 15 strains were isolated from the base wine, 20 strains were isolated during MLF and 12 strains were isolated from the base wine after MLF had been completed. Based on C02 production from glucose and gluconate, 17 strains were classified as facultatively heterofermentative and 37 strains as obligately heterofermentative. Fifteen of the 37 obligately heterofermentative strains were rod-shaped and were regarded as lactobacilli. The remaining 22 strains were oval or cocci-bacilli shaped. The isolates were identified to species level by using numerical analysis of the total soluble cell protein patterns, 16S rRNAsequencing and polymerase chain reaction (PCR) with species-specific primers. The facultative heterofermentative lactobacilli were identified as Lactobacillus paracasei and Lactobacillus p/antarum. The fifteen obligately heterofermentative lactobacilli were identified as members of the species Lactobacillus brevis, Lactobacillus verrniforme, Lactobacillus buchneri and Lactobacillus hi/gardii. The 22 obligate heterofermentative isolates, with a coccoid morphology, could be grouped into two clusters and were identified as Oenococcus oeni. O. oeni was the species responsible for the occurrence of spontaneous MLF in most of the commercial base wines. Lb. brevis, Lb. hi/gardii and Lb. paracasei were also isolated from commercial base wines that had undergone spontaneous MLF. In nine out of 14 experimental base wine samples that had undergone spontaneous MLF, O. oeni was again the predominant species. Lb. brevis, Lb. hi/gardii and Lb. paracasei were identified in the remaining experimental base wine samples. This is the first report of the presence of Lb. perecese! and Lb. vermiforme in brandy base wine. It was shown that the occurrence of spontaneous MLF had a negative effect on the quality of brandy base wine, but that was shown to be due to the different species and strains performing MLF. In the non-preferred distillate samples, Lactobacillus spp. had performed MLF or had developed after or during MLF. / AFRIKAANSE OPSOMMING: Die teenwoordigheid en die vermoë van melksuurbakterieë (MSB) om in wyn te groei, is 'n onderwerp wat al heelwat nagevors is. Melksuurbakterieë is verantwoordelik vir die uitvoering van appelmelksuurgisting (AMG) in wyn. Die voordele verbonde aan appelmelksuurgisting, ten opsigte van die verlaging van die totale suurinhoud en die bydrae tot die verbeterde geur en kompleksiteit van die wyn, is ook al goed bestudeer. Wat die invloed op die finale wynkwaliteit betref, is dit byna onmoontlik om AMG as uitsluitlik gewens óf ongewens te beskou. Die voordele en nadele van AMG is afhanklik van verskeie faktore, nl. wingerdkundige streek, druifkultivar, wynsamestelling, wynmaakpraktyke, asook die styl en doelwitte van die wynmaker. Die produksie van brandewyn is 'n multistapproses waarin die bereidingsmetode van die basiswyn, die distillasietegniek en houtveroudering 'n groot invloed op die finale kwaliteit en chemiese samestelling van die brandewyn het. Die vlugtige verbindings van die basiswyn, wat tydens die dubbele distillasieproses gekonsentreer word, is van wesenlike belang in die bepaling van die aroma en geur van die finale brandewynproduk. Brandewyn is dus inderdaad net so goed soos die basiswyn waarvan dit gestook is. Die doelwitte van hierdie studie was om te bepaal wat die invloed van MSB en die voorkoms van spontane AMG op die kwaliteit van die basiswyn en die distillaat is, asook om die MSB wat vir die voorkoms van spontane AMG verantwoordelik was, te identifiseer. Hierdie studie het bewys dat MSB in hoë getalle teenwoordig was en dat dit in staat is om die spontane AMG van basiswyne uit te voer. Daar is bewys dat die voorkoms van spontaneAMG moontlik van jaar tot jaar kan verskil. In 1998 het 50%, in 1999 het 34% en in 2000 45% van die kommersieel-geproduseerde basiswyn gedeeltelike AMG spontaan voor distillasie ondergaan. Daar is ook gevind dat spontane AMG 'n invloed op die chemiese samestelling en sensoriese kwaliteit van die basiswyn en die distillaat gehad het. Daar was 'n toename in die konsentrasies van etiellaktaat, asynsuur en diëtielsuksinaat in monsters wat spontane AMG ondergaan het. In dieselfde monsters was daar ook 'n afname in die konsentrasies van iso-amielasetaat, etielasetaat, etielkaproaat, heksielasetaat en 2-fenielasetaat. Sensoriese evaluering van die basiswyne en distillate het getoon dat daar betekenisvolle verskille was tussen die monsters wat AMG ondergaan het en dié wat nie AMG ondergaan het nie. Daar is bewys dat die distillate wat nie AMG ondergaan het nie, 'n beter aromaprofiel gehad het as dié wat AMG ondergaan het. Soet geure, soos sjokolade en karamel, en negatiewe geure, soos "chemies" en "oplosmiddel", was prominent in distillate wat AMG ondergaan het. Kruidagtige en vrugtige geure was meer intensief in distillate wat nie AMG ondergaan het nie. Vier-en-vyftig bakteriese rasse, almal Gram-positief en katalase-negatief, is gedurende die verskillende stadia van brandewynproduksie geïsoleer. Sewe rasse is uit druiwesap, 15 rasse gedurende die alkoholiese fermentasie, 20 rasse gedurende AMG en 12 rasse na voltooiing van AMG geïsoleer. Op die basis van koolstofdioksied (C02)-produksie vanaf glukose en glukonaat is 17 rasse as fakultatief heterofermentatief en 37 rasse as obligaat heterofermentatief geklassifiseer. Vyftien van die 37 obligaat-heterofermentatiewe rasse was staafvormig en is as lactobacilli geïdentifiseer. Die oorblywende 22 het ovaal of kokkus-bacillusvormige selmorfologie getoon. Identifikasie tot op spesievlak is gedoen deur van numeriese analise van die totale oplosbare selproteïenprofiele, 16S-rRNAvolgordebepalings en spesie-spesifieke inleiers vir die polimerasekettingreaksie (PKR) gebruik te maak. Die fakultatief-heterofermentatiewe rasse is as Lactobacillus paracasei en Lactobacillus p/antarum geklassifiseer. Die 15 obligaat heterofermentatiewe stafies is as Lactobacillus brevis, Lactobacillus buchneri, Lactobacillus hi/gardii en Lactobacillus vermiforme geïdentifiseer. Die 22 ovaal, obligaat heterofermentatiewe isolate kon in twee groepe ingedeel word en is as Oenococcus oeni geïdentifiseer. Daar is bevind dat O. oeni-isolate vir die voorkoms van spontane AMG in die meeste van die kommersiêle basiswyne verantwoordelik was. Lb. brevis, Lb. hi/gardii en Lb. paracasei is ook uit kommersiêle basiswyne wat spontane AMG ondergaan het, geïsoleer. In nege uit 14 van die eksperimentele basiswyne wat spontane AMG ondergaan het, was O. oeni die dominante spesie. In die oorblywende eksperimentele wyne is Lb. brevis, Lb. hi/gardii en Lb. paracasei aangetref. Hierdie is die eerste vermelding van die teenwoordigheid van Lb. paracasei and Lb. vermiforrne in brandewynbasiswyn. Daar is gevind dat die voorkoms van spontane AMG "n negatiewe invloed op brandewynkwaliteit het, maar dit is as gevolg van die verskeidenheid van MSB-spesies en rasse wat voorkom. In die distillate wat deur die proepaneel afgekeur is, het Lactobacillus spesies die AMG deurgevoer, of het dit tydens of na AMG ontwikkel.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: During wine fermentation, yeasts release extracellular enzymes that significantly impact wine properties. While the extracellular proteins of Saccharomyces cerevisiae have been characterised, those of non-Saccharomyces yeasts remain largely unknown. Most of these enzymes break down sugar polymers or catalyse the liberation of glycosidically-bound molecules. Another category of enzymes of oenological interest is represented by acid proteases that are able to prevent or reduce protein haze, as reported in literature, while simultaneously increasing the assimilable nitrogen content of wine. The liberation of amino acids from peptides and proteins that serve as aroma precursors may also have an indirect effect on wine aroma. In a recent study performed at the Institute for Wine Biotechnology (IWBT), the sequences of two aspartic proteases were retrieved from non-Saccharomyces yeast species isolated from South African wines. The genes, MpAPr1 and CaAPr1, were isolated from two non-Saccharomyces species, Metschnikowia pulcherrima IWBT Y1123 and Candida apicola IWBT Y1384, respectively. However, no further characterization was undertaken. This study aimed to clone these two genes into a recombinant bacterial host for expression and purify the corresponding enzymes as a first step toward characterizing their kinetic properties. Considering that some non-Saccharomyces species have been shown to produce more than one acid protease, an additional aim was to identify novel acid proteases within M. pulcherrima IWBT Y1123. Cloning of the genes and transformation of the expression vectors into E. coli were achieved. Optimal conditions for induced expression were established following extensive optimization. Furthermore, while native extraction of the recombinant proteins was unsuccessful, denaturing conditions allowed their recovery, suggesting that the recombinant proteins are encapsulated into inclusion bodies. Recombinant MpAPr1 was purified by using a nickel based column system and mass fingerprinting of the purified enzyme (MpAPr1) confirmed its identity. Purification was followed by refolding experiments, but yielded poor recovery of active enzymes. Unfortunately, recombinant expression of CaAPr1 could not be observed for reasons yet to be elucidated that may include the large sequence dissimilarities between CaAPr1 and MpAPr1. Finally, Southern blot analysis on the genomes of M. pulcherrima IWBT Y1123 and C. apicola IWBT Y1384 revealed that both possess at least one additional protease other than those previously described. Further analysis of the extracellular proteome of M. pulcherrima IWBT Y1123 also confirmed the presence of at least one enzyme able to hydrolyze BSA at a low pH. Unfortunately, mass fingerprinting performed on the entire extracellular proteome and on small groups of proteins thereof did not allow the identification of these enzymes. / AFRIKAANSE OPSOMMING: Gedurende fermentasie van druiwe sap skei gis ekstrasellulêre ensieme af wat ‘n aanmerklike impak op wyn eienskappe het. Terwyl die ekstrasellulêre proteïene vanaf Saccharomyces cerevisiae al gekarakteriseer is, bly die van nie-Saccharomyces spesies grootliks onbekend. Meeste van hierdie ensieme breek suiker polimere af of kataliseer die vrystelling van glikosiediese verbonde molekules. ‘n Ander klas van ensieme wat van belang is vir oenologie word voorgestel deur proteases wat in staat is daartoe om proteïenewaas te verminder, soos voorheen geraporteer is in literatuur, terwyl dit terselfde tyd die assimileerbare stikstof inhoud kan vermeerder. Die vrystelling van aminosure vanaf peptiede en/of proteïene wat as aroma voorlopers dien mag ook ‘n indirekte effek op die wyn se aroma profiel hê. In ‘n onlangse studie wat uitgevoer is by die Instituut vir Wynbiotegnologie (IWBT) was die volgordes van twee aspartiese proteases bepaal vanaf twee nie-Saccharomyces gis spesies wat geisoleer was uit Suid-Afrikaanse wyne. Die gene MpAPr1 en CaAPr1, was afsonderlik geisoleer vanuit twee nie- Saccharomyces giste, Metschnikowia pulcherrima IWBT Y1123 en Candida apicola IWBT Y1384. Egter was daar geen verder karakterisering van hierdie ensieme nie. Die doel van hierdie studie is om die bogenoemde gene in ‘n rekombinante bakteriese gasheer te kloneer vir uitdrukking en suiwering as ‘n eerste stap tot karakterisering van hul kinetiese eienskappe. Om in ag te neem dat sommige nie-Saccharomyces spesies meer as een protease produseer was ‘n aditionele mikpunt om vir nuwe suur proteases te soek binne M. pulcherrima IWBT Y1123. Klonering van hierdie gene en transformasie van die uitdrukkings vektore in E. coli was suksesvol. Optimale kondisies vir die induksie van ekspressie was bevestig na omvattende optimalisering. Verder, terwyl inheemse ekstraksie van die rekombinante proteïene onsuksesvol was, het denatureerende kondisies toegelaat vir suksesvolle ekstraksie, wat voorgestel het dat die rekombinante proteïene geinkapsileer word in inklusie liggame. Rekombinante MpAPr1 was gesuiwer deur gebruik te maak van ‘n niekel gebaseerde kolom sisteem en massa petied fingerafdrukke van die gesuiwerde ensiem (MpAPr1) het die identiteit bevestig. Suiwering was gevolg deur hervouing eksperimente, maar het swak opbrengste gelewer van die aktiewe ensiem. Ongelukkig kon die rekombinante ekspressie van CaAPr1 nie gevisualiseer word nie vir redes wat nog bevestig moet word, maar wat mag behels dat daar groot volgorde veskille tussen MpAPr1 en CaAPr1 kan wees. Uiteindelik was Southern blot hibridiseering analises uitgevoer op die genome van albei M. pulcherrima IWBT Y1123 en C. apicola IWBT Y1384 wat voorgestel het dat albei ten minste een addisionele protease, anders as die wat voorheen geidentifiseer was, bevat. Verder analiese van die ekstrasellulêre proteoom van M. pulcherrima IWBT Y1123 het ook die teenwoordigheid van ten minste een ensiem bevestig wat die vermoë het om BSA te hidroliseer by ‘n lae pH. Ongelukkig het massa peptied vingerafdrukbepaling wat uitgevoer was op die hele ekstrasellulêre proteoom en op klein groepe protein nie identifikasie van hierdie ensieme bevestig nie.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The use of non-Saccharomyces yeasts together with Saccharomyces cerevisiae in mixed starter cultures has become an accepted oenological tool to enhance the organoleptic properties of wine. Recent studies have indeed demonstrated the positive contribution that non- Saccharomyces yeasts may have on the bouquet of wine. These mixed starter cultures are characterized by high inoculation levels of individual strains into the must, and each strain in turn is characterized by its own specific metabolic activity. These factors lead to a multitude of interactions occurring between the individual populations within the must. The fundamental mechanisms which drive these interactions are still largely unknown, but several studies have been conducted in order to investigate the metabolic outcome of these interactions. In this study, we endeavour to further characterize the interactions which occur between four individual non-Saccharomyces yeast strains in mixed culture fermentation with S. cerevisiae. Metschnikowia pulcherrima IWBT Y1337, Lachancea thermotolerans IWBT Y1240, Issatchenkia orientalis Y1161 and Torulaspora delbrueckii CRBO LO544 were used in mixed culture fermentations with a commercial strain of S. cerevisiae at an inoculation ratio of 10:1 (non-Saccharomyces: S. cerevisiae). The biomass evolution and fermentation kinetics of both participating species were affected by the high cell density of the other, with neither population reaching the maximal density attained by the pure culture fermentation. The final wine composition of each individual mixed fermentation showed clear differences, from the pure cultured S. cerevisiae and from each other, based on the concentrations of the major volatile compounds found in the wine. Upon further characterization of these specific mixed culture fermentations, it was found that each individual combination of non-Saccharomyces and S. cerevisiae produced similar increases and decreases of certain major volatile compounds as demonstrated by previous authors, using the same combination of non-Saccharomyces species together with S. cerevisiae. From a winemaking perspective, the use of these non- Saccharomyces yeast strains in combination with S. cerevisiae could be a useful strategy to diversify the chemical composition of wine, by increasing the concentration of certain desirable volatile compounds and by modulating the concentration of undesirable metabolites. Furthermore, this research serves as a foundation for further elucidation of the interactions which drive these metabolic outcomes in response to the high cell density of two yeast populations in mixed culture fermentations.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The alcoholic beverage industry needs objective analysis of grape juice and liqueur quality. Fourier transform infrared (FT-IR) spectroscopy with multivariate data analysis techniques is widely used in wine laboratories across South Africa for accurate, fast and high sample throughput analyses. In this study the potential of FT-IR spectroscopy is evaluated for the quantification of ammonia in freshly pressed grape juice. FT-IR spectroscopy is evaluated, using two different spectrometers, in respectively attenuated total reflection (ATR) - and transmission scanning modes for the quantification of alcohol, pH and invert sugar in spirit-based liqueurs. The ultimate aim was to implement the PLS regression algorithms developed at an industrial cellar and replace the complex and lengthy reference methods used at the time of this study. Principle component analysis (PCA) was performed prior to the calibration step to identify groupings and patterns within the spectra. The PLS calibration models were developed from samples collected at the cellar and using partial least square (PLS) regression. The models were evaluated using the performance criteria coefficient of determination (R2) and root mean squared error of cross validation (RMSECV) at calibration stage, and root mean square error of prediction (RMSEP) and residual predictive deviation ratio (RPD) at validation stage. The average RMSEP (1.88 mg/L) of the ammonia PLS calibration model was in agreement with the standard error of laboratory (SEL = 1.54 mg/L). The R2 (92.05) and average RPD (3.3) proposed a model with excellent precision for screening purposes that was ready to be transferred for use by the laboratory. The r2 values for the alcohol, pH and invert sugar PLS calibration models obtained in ATR and transmission, indicated good to excellent precision (80<r2<100). The alcohol PLS calibration model obtained in transmission was suitable for quality- and process control purposes (RPD = 21.2), while the invert sugar PLS calibration model for quality control purposes (5<RPD<6.4). The pH and invert sugar calibration models obtained in ATR were suitable for screening purposes with RPD = 3.6 and RPD = 4.8, respectively. These PLS regression algorithms were implemented at the cellar. The pH PLS calibration model obtained in transmission was suitable for rough screening of samples (RPD = 2.7) and future development was neccesary to increase the predictability of the model. The results obtained in this study made a significant contribution towards validation of FT-MIR as a powerful tool for rapid quantification of quality indicating parameters in wine and spirit-based liqueurs. The contribution is particularly valuable in the context of ongoing research to improve the quality of products at the cellar to meet consumer demands. The knowledge gained on quantification of quality indication parameters of spirit-based liqueurs is novel and this is one of the first reports on implementation of mid-infrared (MIR) spectroscopy for the quality control of South African spirit-based liqueurs. / AFRIKAANSE OPSOMMING: Die wynindustrie benodig objektiewe analises van druiwesap- en likeurgehalte. Fourier-transformasie- infrarooi (FT-IR) spektroskopie met multiveranderlike statistiese metodes word gebruik in wynlaboratoriums regoor Suid-Afrika vir akkurate, vinnige en hoë monsterdeurset ontledings. In hierdie studie is die potensiaal van FT-IR spektroskopie geëvalueer vir die kwantifisering van ammoniak in die sap van vars geparste wyndruiwe. Twee verskillende FT-IR spektroskopie instrumente, in onderskeidelik (verswakte totale refleksie, ATR) - en transmissie skandering is gebruik vir die kwantifisering van alkohol, pH en invertsuiker in spiritus-gebaseerde likeurs. Die uiteindelike doel was om die parsiële kleinste kwadraat (PKK)- regressie algoritmes wat ontwikkel is, by 'n industriële kelder te implementeer en die komplekse en tydrowende verwysingmetodes wat tydens die studie in die kelder gebruik is te vervang. Verskeie multiveranderlike hoofkomponentanalise (MVK) is uitgevoer voor die kalibrasie stap, met die doel om groeperings en patrone in die spektra te identifiseer. Die PKK kalibrasiemodelle is ontwikkel van monsters wat by die kelder versamel is en die spektra is gebruik in die PKK regressies. Tydens die kalibrasiefase is die modelle geëvalueer met behulp van die bepalingskoëffisiënt (R2) en gemiddelde kalibrasieprediksiefout en tydens die validasiefase, met behulp van die standaardvoorspellingsfout (SVF) en relatiewe voorspellingsafwyking (RVA). Die gemiddelde SVF (1.88 mg/L) van die ammoniak kalibrasiemodel was in ooreenstemming met die standaard fout van die laboratorium (SEL = 1.54 mg/L). Die R2 (92.05) en die gemiddelde RVA (3.3) dui op ‘n model met uitstekende presiesheid wat gereed is vir oordra en gebruik deur die industrie. Die R2 waardes vir die alkohol-, pH- en invertsuiker –kalibrasie-modelle wat met ATR en transmissie vir die likeurmonsters ontwikkel is, dui op goeie tot uitstekende presiesheid (80<R2<100). Die alkoholkalibrasiemodel wat ontwikkel is in transmissie, is geskik vir kwaliteits- en prosesbeheerdoelwitte (RVA = 21.2), terwyl die invertsuiker kalibrasiemodel geskik is vir kwaliteitsbeheer doelwitte (5<RVA<6.4). Die pH en invertsuiker kalibrasiemodelle in ATR is geskik vir vinnige evalueringsdoelwitte, met RVA = 3.6 en RVA = 4.8 waardes, onderskeidelik. Hierdie algoritmes is ook in die kelder geimplementeer. Die pH kalibrasiemodel in transmissie was geskik vir vinnige evalueringsdoelwitte (RVA = 2.7) en toekomstige ontwikkeling is nodig om die voorspellingsakkuraatheidvan die model te verbeter. Die resultate van hierdie studie het ‘n betekenisvolle bydrae gelewer tot bevestiging van infrarooi spektroskopie as 'n kragtige tegnologie vir die vinnige kwantifisering van gehalteparameters in druiwesap en spiritus-gebaseerde likeurs. Die bydrae is veral waardevol in die konteks van voortgesette navorsing om die kwaliteit van produkte by die kelder te verbeter en aan verbruikerseise te voldoen. Die studie vir die kwantifisering van gehalteparameters in spiritus-gebaseerde likeurs is eerste in sy soort en een van die gerapporteerde verslae vir die implementering van infrarooi spektroskopie vir gehaltebeheer van Suid-Afrikaanse spiritus-gebaseerde likeurs.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The production of wine globally has increased over the past years, increasing the volume of water used and wastewater generated for every litre of wine produced. In the past, the small volumes of winery wastewater that were produced by wineries had little effect on the immediate environment. However, with the increasing wine production all around the world, winery wastewater is a rising concern for the contamination of soil and subsurface flow. In order to fully understand the impacts of winery wastewater, it is important to establish the volumes and chemical characteristics of the wastewater, before considering possible treatments. The first aim of this study was to determine the influence of certain winemaking practices on the water usage. Two wineries in the Stellenbosch Winelands District were monitored during two harvests and one post-harvest season. It was evident through this study that water plays a vital role during the production of wine and that water is needed at virtually all the winemaking steps. However, the volume of clean water needed differs immensely during the course of the production process. It was noticed that throughout the harvest period at both wineries the clean water demand was highest and decreased during the course of the post-harvest period and steadily increased again towards the end of the year. The harvest period contributes between 30 and 40% of the yearly water usage at the respective wineries. It was also noticed that certain winemaking practices including filtering with a bulk filter, washing of barrels and bottling contributes heavily to the water usage throughout the year. Activities that increase water usage during harvest include the washing of the press and processing a combination of red and white grapes on the same day. Furthermore, it was identified that one of the wineries used a smaller volume of water on a daily basis and per tonnage during harvest than the other, indicating that the cleaner production strategy established 10 years earlier has a positive impact on their water usage. The second aim of this study was to monitor the raw and treated winery wastewater from the two wineries during a period of 15 months, including two harvests and one post-harvest season. This was done to investigate the characteristics of the raw and treated wastewater. Firstly, to determine the impact of the different winemaking practices on the chemical composition of the wastewater and secondly, to determine the efficiency of the existing constructed wetlands on the wastewater and the characteristics of the treated wastewater. From this study it was possible to make two main observations concerning the chemical oxygen demand (COD) concentrations of the two wineries. Primarily, it was observed there were variations in the raw wastewater characteristics of the two wineries and above all, that both wineries showed a decrease in the COD of the raw wastewater produced. Not only did the decrease in the raw wastewater COD over this period show promising results when a cleaner production plan is established and managed it also seems to show a decrease in the volumes of water used by the respective wineries and increase in quality. / AFRIKAANSE OPSOMMING: Gedurende die afgelope paar jaar het wynproduksie wêreldwyd toegeneem en as gevolg hiervan toenemende hoeveelhede water gebruik en afvalwater gegenereer. In die verlede het die klein volumes kelderafvalwater wat deur wynkelders geproduseer is min effek op die onmiddelike omgewing gehad, maar gegewe die toenemende produksie van wyn regoor die wêreld is daar groeiende kommer oor die besoedeling van gronde en ondergrondse vloei deur kelderafvalwater. Dit is belangrik om die volumes en chemiese eienskappe van die afvalwater te bepaal om die impak van die water ten volle te verstaan, voordat moontlike behandelings oorweeg word Die eerste doel van hierdie studie was om te bepaal hoe sekere wynmaakpraktyke watergebruik beïnvloed. Twee wynkelders in die Stellenbosch Wynland Distrik is gedurende twee parsseisoene en een na-pars seisoen gemonitor. Hierdeur het dit duidelik geword dat water ‘n noodsaaklike rol speel in wynproduksie en benodig word vir feitlik alle stappe in die wynmaakproses. Die volume skoon water wat benodig word verskil wel noemenswaardig tydens die produksieproses. Die gebruik van skoon water van beide kelders was hoog tydens die parsseisoen, het afgeneem gedurende die loop van die na-pars periode en het geleidelik weer toegeneem teen die einde van die jaar. Die parsseisoen dra tussen 30 en 40% by tot die jaarlikse waterverbruik van die onderskeie kelders. Dit is ook opgemerk dat sekere wynmaakpraktyke, insluitend filtrasie met ‘n grootmaat filter, die was van vate en bottelering, grootliks bydrae tot die waterverbruik deur die loop van die jaar. Aktiwiteite wat waterverbruik tydens parstyd verhoog sluit in die gebruik van die pers en die verwerking van ‘n kombinasie van rooi en wit druiwe op dieselfde dag. Daar is ook vasgestel dat een van die wynkelders tydens parstyd ‘n kleiner volume water gebruik op ‘n daaglikse basis asook per tonnemaat wat daarop dui dat die “skoner” produksie strategie wat dié kelder 10 jaar gelede gevestig het wel ‘n positiewe impak op waterverbruik het. Die tweede doel van hierdie studie was om die onbehandelde en behandelde afvalwater van hierdie twee wynkelders te monitor oor 'n tydperk van 15 maande, wat twee paste en een na-pars seisoen insluit. Dit is gedoen om die impak van verskillende wynmaakpraktyke op die chemiese samestelling van die afvalwater te ondersoek asook om die doeltreffendheid van bestaande kunsmatige vleilande in terme van afvalwaterbehandeling te bepaal en die eienskappe van die behandelde afvalwater te ondersoek. Gevolglik is twee belangrike waarnemings oor die chemiese suurstof behoefte (CSB) konsentrasie van die twee wynkelders gemaak. Variasies in die onbehandelde afvalwater eienskappe is waargeneem by beide wynkelders en daar was ‘n afname in CSB van die onbehandelde afvalwater by beide wynkelders. Die afname in CSB van die onbehandelde afvalwater oor hierdie tydperk is belowend en dit blyk dat wanneer ‘n “skoner” produksie plan opgestel en bestuur word dit wel ‘n afname in waterverbruik en verhoog in kwaliteit by die kelders tot gevolg het.

Made available in DSpace on 2016-03-07T19:21:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-05-25. Added 1 bitstream(s) on 2016-03-07T19:25:29Z : No. of bitstreams: 1 000858832.pdf: 994543 bytes, checksum: 2432f925f648e3fe972141c68c3b2506 (MD5) / O objetivo deste trabalho foi analisar isotopicamente o gás carbônico de espumantes para detectar adulteração, utilizando o método de análise isotópica para determinar a origem deste gás; se proveniente de plantas dos ciclos fotossintéticos C3 (uva), C4 (açúcar de cana) ou de outra fonte. Para isso, foram analisadas amostras comerciais de espumante e espumante moscatel, espumantes elaborados em laboratório, sumo de uva, açúcar e gás carbônico comercial. Também foram analisadas outras bebidas carbonatadas (água mineral, refrigerantes, vinhos, etc.). Os resultados foram submetidos à análise de variância e teste de Tukey para a detecção de possíveis diferenças entre as médias das razões isotópicas de 13C/12C, ao nível de significância de p <0,05. Seguindo a legislação brasileira para vinhos espumantes determinou-se o intervalo de valores possíveis de δ13C para que as bebidas estivessem em acordo com as normas. Em relação aos espumantes, quatro estavam fora do intervalo de valores estabelecido; para os espumantes moscatéis, nenhum estava em desacordo com a legislação brasileira. / The objective of this study was to analyze isotopically carbonic gas sparkling to detect tampering using the isotopic analysis method to determine the source of carbon dioxide (whether from plants the photosynthetic cycles C3 (grape and beet), C4 (sugar cane) or from another source. For this purpose, samples were analyzed Muscat commercial sparkling wine and sparkling wine, sparkling prepared in the laboratory, grape juice, sugar and commercial CO2. They also analyzed other carbonated beverages (mineral water, soft drinks, wines, etc.). The results were submitted to ANOVA and Tukey test for the detection of possible differences between the means of the isotopic ratios 13C / 12C, at a significance level of p <0.05. Following the Brazilian legislation for sparkling wines determined the possible range of values of δ13C for the drinks were in accordance with the rules. Regarding sparkling, four were outside the range established; for muscat sparkling, none was at odds with Brazilian law.

Made available in DSpace on 2014-06-11T19:26:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-07-31Bitstream added on 2014-06-13T18:30:35Z : No. of bitstreams: 1 correia_js_me_botfca.pdf: 402295 bytes, checksum: 099cc93f3511a57ff83eab684b636900 (MD5) / Universidade Estadual Paulista (UNESP) / As disponibilidades de radiação solar e de água para irrigação contribuem para a produção de uvas ao longo do ano no Vale do Submédio São Francisco. Diante da expansão da vitivinicultura nesta região, a demanda por pesquisas em relação ao manejo adequado e prático da videira para a região semiárida brasileira tem aumentado. Desta forma, o presente trabalho teve o objetivo de avaliar a influência de estratégias de irrigação na cultura da videira de vinho, e suas possíveis influências na produtividade e qualidade das uvas. O experimento foi conduzido na Embrapa Semiárido, em Petrolina -PE, entre 10 de novembro de 2010 a 28 de fevereiro de 2011, com a videira cv. Syrah/Paulsen 1103, plantada em espaçamento de 1 x 3 m, em um Argissolo Vermelho Amarelo Eutrófico Latossólico. O sistema de irrigação utilizado foi o gotejamento, com emissores espaçados em 0,5 m na linha de plantio, com vazão de 2,5 L.h-1. O delineamento utilizado foi o de blocos casualizados, com 3 tratamentos e 4 repetições. Os tratamentos foram: 1- irrigação plena (IP), irrigação realizada com base na reposição da evapotranspiração da cultura (ETc), durante todo o ciclo de produção; 2 - irrigação com déficit controlado (IDC), irrigação interrompida aos 65 dias após a poda de produção (dapp), porém com irrigações aos 91, 92 e 93 dapp; e 3 - irrigação deficitária (ID), irrigação interrompida aos 65 dapp até a colheita aos 110 dapp. A ETc foi estimada pela relação entre evapotranspiração de referência (ETo), e o coeficiente de cultura (Kc). O potencial hídrico foliar (Ψfoliar) foi medido em cada tratamento, do estádio fenológico de maturação até o estádio de cachos maduros. Durante o experimento, ocorreu uma precipitação total de 252 mm. A ETc durante... / The availability of solar radiation and water for irrigation contribute to the wine grape production throughout the year in the Lower Middle São Francisco Valley. In consequence of increase of vine growing area in this region, the research demand about suitable and feasible vine water management in the Brazilian semi-arid region has increased. Thus, this study aimed to evaluate the influence of irrigation strategies in vineyards, and their possible effects on yield and quality of wine grapes. The experiment was carried out at Embrapa Tropical Semi-arid, in Petrolina, State of Pernambuco, Brazil, from November 10, 2010, to February 28, 2011. The grapevive cv. Syrah, grafted on Paulsen 1103, was planted at a spacing grid of 1 x 3 m, in a Argissolo Vermelho Amarelo Eutrófico Latossólico. Drip irrigation was used, with emitters spaced 0.5 m within the plant row, with 2.5 L.h-1 flow. The design was a randomized complete block with three treatments and four replications. The treatments were: 1 - full irrigation (FI), where irrigation was performed based on crop evapotranspiration (ETc, mm) during all growing season, without water restriction to the vines; 2 – regulated deficit irrigation (RDI), where irrigation was performed based on ETc until 65 days after pruning (dap), but performed at 91, 92, and 93 dap and 3 – deficit irrigation (ID) – where irrigation interrupted at 65 dap until harvest at 110 dap. The ETc was estimated by the relationship between reference evapotranspiration (ETo), and crop coefficient (kc) for each phenological phase of vine. The leaf water potential (Ψpd) was measured... (Complete abstract click electronic access below)