Thesis (PhD)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Yeasts produce a broad range of aroma-active volatile esters and higher alcohols during alcoholic fermentation. Some of these esters and higher alcohols are important for the fruity flavors and therefore the final quality of wine and other fermented beverages. Esters are produced and hydrolyzed by alcohol acetyltransferases and esterases, respectively. In yeast, ester-synthesizing activities are represented by two alcohol acetyltransferases encoded by the ATFI and ATF2 genes, and by an ethanol hexanoyl transferase encoded by the EHTI gene. Atfl p and Atf2p appear responsible for the production of ethyl acetate and isoamyl acetate, while Ehtl p synthesizes ethyl hexanoate from ethanol and hexanoyl-CoA. Although a fair amount of information is available regarding the ATF 1 gene, limited information is available on the remaining alcohol acetyltransferases. Only two genes that code for esterases have been identified in yeast, namely lAHI and TIPI. It has also been shown that the balance between alcohol acetyltransferases and esterases is important for the net rate of ester accumulation. Higher alcohols are synthesized from the a-keto-acids in the branched-chain amino acid metabolic pathway by decarboxylation and reduction. The transamination of the amino acid to the respective a-keto-acid is catalyzed by mitochondrial and cytosolic branched-chain amino acid transferases, which are encoded by the BATI and BAT2 genes, respectively. In recent years, a strong scientific and industrial interest in the metabolism of flavoractive compounds has emerged, but information regarding the roles of specific enzymes and the physiological relevance of their metabolism remains limited. The aim of this project was to investigate the physiological and metabolic consequences of changes in the expression levels of some of the key enzymes involved in aroma compound production. The consequences of these changes on the chemical composition and the fermentation bouquet of wines and distillates were also investigated. The first part of the section on the results in this dissertation reports on the role and relative importance of the Saccharomyces cerevisiae enzymes involved in ester metabolism, namely Atflp, Atf2p, Ehtlp, Iahlp and Tiplp. The corresponding genes were overexpressed in a laboratory strain of S. cerevisiae, BY4742, and in a widely used commercial wine yeast strain, VIN13. Table wine and base wines for distillation were prepared with these VIN13 transformed strains. The ester concentrations and aroma profiles of the wines and distillates were analyzed and compared. The data indicated that the overexpression of ATF 1 and ATF2 increased the concentrations of ethyl acetate, isoamyl acetate, 2-pheylethyl acetate and ethyl caproate, while the overexpression of JAHI resulted in a significant decrease in the concentrations of ethyl acetate, isoamyl acetate, hexyl acetate and 2-phenylethyl acetate. The overexpression of EHTI resulted in a marked increase in the concentrations of ethyl caproate, ethyl caprylate and ethyl caprate, while the overexpression of TJP1 did not decrease the concentrations of any of the esters. In most cases, there was a correlation between the increase in esters and the decrease in higher alcohols. The data suggest that yeast balances the amount of different esters produced through alcohol acetyltransferases and esterases, and that, in some cases, these enzymes appear to overlap in function and/or influence each other's activity. In the second part of the results section, the consequences of the deletion and the overexpression of two genes, BATl and BAT2, which encode transaminases that contribute to the metabolism of higher alcohols, were investigated. The genes were both disrupted in a S. cerevisiae BY4742, and overexpressed in both this laboratory strain and in the VIN13 wine yeast strain. The effects of these modifications on the general physiology of the corresponding yeast strains and on higher alcohol metabolism were assessed in a range of growth conditions, including aerobic and anaerobic growth conditions, in the presence of glucose or raffinose as sole carbon source and growth in the presence of various concentrations of amino acids. Table wine and base wines for distillation were prepared with the modified industrial strains and the concentrations of the higher alcohols and the aroma profiles of the wine and distillates were analyzed and compared. Batl deletion seemed to be lethal under the conditions that were created, and therefore only the bat2!:!.strain, together with the BATI and BAT2 overexpression strains, were investigated. These modifications did not appear to significantly affect the general physiology of the strains. The results obtained indicated that the overexpression of BATI increased the concentrations of isoamyl alcohol and isoamyl acetate, and, to a lesser extent, the concentrations of isobutanol and isobutyric acid. The overexpression of the BAT2 gene resulted in a substantial increase in the levels of isobutanol, isobutyric acid and propionic acid production, and a modest increase in the level of propanol and isovaleric acid. Interestingly, the overexpression of BAT2 led to a decrease in isoamyl alcohol and isoamyl acetate concentrations. Sensory analyses indicated that the wines and distillates produced with the strains in which the BATl and BAT2 genes were overexpressed had more fruity characteristics (peach and apricot aromas) than the wines produced by the wild-type strains. This study offers new prospects for the development of wine yeast starter strains with optimized ester and higher alcohol-producing capability that could assist winemakers in their efforts to consistently produce wine to definable specifications and styles and a predetermined flavor profile. / AFRIKAANSE OPSOMMING: Gedurende fermentasie produseer giste 'n wye verskeidenheid vlugtige aromatiese esters en hoër alkohole. Sommige van hierdie esters en hoër alkohole is belangrik vir die vrugtige geure en dra dus by tot die finale kwaliteit van wyn en ander gefermenteerde drankies. Esters word onderskeidelik deur alkoholasetieltranferases en esterases geproduseer en gehidroliseer. In giste word die ester-sintetiserende aktiwiteite deur twee alkoholasetieltransferases verteenwoordig wat deur die ATFI-en ATF2-gene, asook 'n etanolheksanoïeltransferase wat deur die EHTl-geen, gekodeer word. Dit blyk dat ATFlp en ATF2p verantwoordelik is vir die produksie van etielasetaat en isoamielasetaat, terwyl Ehtl p-etielheksanoaat vanaf etanol en heksanoïel-CoA sintetiseer. Alhoewel daar 'n redelike hoeveelheid inligting t.o.v die ATF I-geen beskikbaar is, is daar weinig inligting oor die res van die aloholasetieltransferases. Slegs twee gene wat vir esterases kodeer, is in gis geïdentifiseer, naamlik IAHI en TIPI. Daar is ook bewys dat 'n balans tussen die alkoholasetieltransferases en esterases baie belangrik is vir die netto-tempo van ester-akkumulasie. Hoër alkohole word gesintetiseer vanaf a-keto sure in die vertakte-ketting aminosuur metaboliese pad deur dekarboksilasie en reduksie. Die transaminasie van die aminosuur na die onderkeidelike a-ketosuur word deur vertakte-ketting aminosuur transferases, geleë in die mitochondrion en sitosol, en gekodeer deur BATl- en BAT2-gene, gekataliseer. In die laaste paar jare het daar 'n sterk wetenskaplike, asook industrïele, belangstelling in die metabolisme van aroma-aktiewe komponente te voorskyn gekom, maar inligting in verband met die rol van spesifieke ensieme en die fisiologiese belangrikheid van hul metabolisme is egter beperk. Die doel van hierdie projek was om die fisiologiese en metaboliese gevolge van veranderinge in die ekspressievlakke van sommige sleutelensieme betrokke by aromakomponent-produksie te ondersoek. Die gevolge van hierdie veranderinge op chemiese vlakke, asook hoe die fermentasie-aroma van die wyne en distillate beïnvloed word, is ook bestudeer. Die eerste gedeelte van die resultate rapporteer oor die rol en relatiewe belangrikheid van die Saccharomyces cerevisiae-ensieme betrokke by estermetabolisme, naamlik Atfl p, Atf2p, Ehtlp, Iahlp en Tiplp. Die gene was ooruitgedruk in 'n laboratoriurnras van S. cerevisiae, BY4742, asook in 'n kommersïele wyngisras, VIN13. Tafelwyne en basiswyne vir distillasie is gemaak met die getransformeerde VIN13-rasse. Die esterkonsentrasies en aromaprofiele van die wyne en distillate is ontleed en vergelyk. Die data het gewys dat die ooruitdrukking van ATFI- en ATF2-gene 'n verhoging in etielasetaat, isoamielasetaat, 2-fenieletielasetaat en etielkaproaat veroorsaak het, terwyl ooruitdrukking van !AHI 'n betekenisvolle afname in etielasetaat-, isoamielasetaat-, heksielasetaat- en 2-fenieletielasetaat-konsentrasies veroorsaak het. Die ooruitdrukking van EHTI het 'n duidelike verhoging in etielkaproaat, etielkaprilaat en etielkapraat veroorsaak en die ooruitdrukking van TIPIhet geen van die esterkonsentrasies verander nie. In die meeste gevalle was daar nie 'n korrelasie tussen die toename in esters en afname in hoër alkohole nie. Die data stelook voor dat die gis 'n balans tussen die verskillende esters handhaaf deur middel van die alkoholasetieltrasferases en esterases, en in sommige gevalle blyk dit dat die ensieme dieselfde funksies het en/of mekaar se aktiwiteit beïnvloed. In die tweede gedeelte van die resultate is die oorsake van delesie en ooruitdrukking van twee gene, BAT1 en BAT2, wat kodeer vir transaminases wat tot hoër alkohol metabolisme bydra, bestudeer. Die gene is uitgeslaan in S. cerevisiae BY4742 en ooruitgedruk in BY4742 en in die wyngisras VIN13. Die effekte van hierdie modifikasies op die algemene fisiologie van die verskillende gisrasse en op hoëralkoholmetabolisme is onder 'n verskeidenheid kondisies bestudeer, naamlik aërobies en anaërobiese groeikondisies, in die teenwoordigheid van glukose of raffinose as die enigste koolstofbron, asook in die teenwoordigheid van 'n verskeidenheid konsentrasies aminosure. Tafelwyne en basiswyne vir distillasie is gemaak met die gemodifiseerde industrïele rasse en die konsentrasies van die hoër alkohole en aromaprofiele van die wyne en distillate is ontleed en vergelyk. Bat1-delesie was dodelik onder die kondisies, daarom is slegs die batlts-tes tesame met die BAT1 en BAT2 wat in die rasse ooruitgedruk is, bestudeer. Die modifikasies het nie 'n beduidende effek op die algemene fisiologie van die rasse getoon nie. Die data het wel getoon dat die ooruitdrukking van BAT1 'n verhoging in isoamielalkohol- en isoamielasetaatkonsentrasies, en tot 'n mindere mate isobutielalkohol- en isobottersuur-konsentrasies, veroorsaak het. Die ooruitdrukking van BAT2 het 'n beduidende toename in isobutanol-, isobottersuur- en propioonsuurkonsentrasies en 'n kleinere toename in propanol- en isovaleriaansuur veroorsaak. Die ooruitdrukking van BAT2 het ook gelei tot 'n afname in isoamielalkohol- en isoamielasetaatkonsentrasies. Sensoriese analises het getoon dat die wyne en distillate wat geproduseer is met die rasse waarin die BAT1 en BAT2 gene ooruitgedruk is meer vrugtige eienskappe (perske- en appelkoos-aromas) getoon het as die wyne wat deur die wildetipe rasse geproduseer is. Die studie lewer nuwe vooruitsigte vir die ontwikkeling van wyngiste met geoptimiseerde ester en hoër alkohol produserende eienskappe wat die wynmakers in staat kan stelom wyne te produseer met gedefinieerde spesifikasies en style en 'n voorafbepaalde aromaprofiel.

Dissertation (PhD)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Brandy production is a multi-step process that involves grape harvesting, base wine fermentation, distillation, wood maturation and blending. Within each of these production process steps there are a number of factors that can influence the composition and resultant quality of the base wine, unaged and wood matured distillates. These factors include geographic and climatic features of the origin of grapes used, viticultural practices, grape maturity, grape variety, vintage variation, vinification techniques, storage of the base wine prior to distillation, distillation technique, age and origin of oak wood used for maturation and barrel toasting levels. The composition of flavour is extremely complex in wine and distilled beverages such as brandy. A multitude of compounds can take part in the formation of flavour, and it is rare that a particular compound, that is solely responsible for nuances of a specific flavour, is identified. Thus, taking brandy production factors and the nature of aroma and flavour into account, it is clear that thorough understanding of the complexities affecting the perception of quality in brandy is difficult. In commercial brandy production, standard operating procedures do not allow for the separate distillation of brandy base wines from different producers and mixing of base wines from different regions and producers thus occurs. This makes it difficult to determine whether the quality determination of the base wine is in fact an indication of the quality of the resultant distillate after the required period of wood maturation. Therefore, the aim of this study is to determine whether there is any merit in storing and distilling brandy base wines from different producers and regions separately. This was done by firstly determining the demographic and production factors that influence brandy base wine composition. Secondly, the influence of brandy base wine composition on the quality of the respective unaged potstill distillates as well as the ultimate style and quality of the threeyear old wood matured potstill distillates was determined. For this purpose, four potstills with a capacity of 2000 L each were isolated and used for commercial scale distillations of 33 and 25 brandy base wines in 1999 and 2000, respectively, at the DisteIl distillery in Worcester. The experimental outlay used in the study closely emulated Distell's standard operating procedures for commercial brandy production. Chenin blanc and Colombar are the two most popular grape varietals used in the making of brandy base wine in South Africa. Due to the complexity of the brandy production process, the first part of the study only focussed on South African young Chenin blanc wines, with a predominantly fermentation derived aroma. The concentration of iso-amyl acetate, hexyl acetate, ethyl caprylate, ethyl caprate, 2-phenethyl acetate and octanoic acid was significantly higher in wines awarded gold and silver medals and decreased significantly with subsequent decreases in quality categories. Ethyl lactate exhibited the opposite pattern. A quality predictor model based on the behaviour of 21 volatile compounds quantified in these wines had a resonable prediction accuracy when having to predict the quality of wines made in the same vintages as it had been trained on. It was significantly poorer when tested on a completely different vintage of wines to the ones it had been trained on. The number of vintages, number of wines per vintage and the number of compounds quantified for the model influence its prediction accuracy. Twenty-seven volatile compounds were quantified in 33 and 25 brandy base wines, their unaged and three year old distillates from 1999 and 2000, respectively. ANOVA and CART analysis showed that vintage, region, harvest time, choice of cultivar and yeast strain can have a significant influence on the volatile compound composition of brandy base wines, their unaged and three year old distillates. These factors as well as the volatile compound composition were also found to influence the sensory quality of these products. Base wines, unaged and three year old distillates originating from the De Dooms region, which predominantly cultivates table grapes, were of significantly lower quality than those from the remaining regions. Products made from grapes harvested early in the season were of significantly higher quality. The volatile aroma compound composition was found to differ significantly between the 1999 and 2000 base wines and distillates, irrespective of the exclusion of those samples that had undergone partial or complete malolactic fermentation. Consequently, quality indicating compounds may vary from vintage to vintage. The relationship between the quality of brandy base wines and the concentration of n-butanol, iso-amyl acetate, ethyl lactate, ethyl caprylate, octanoic- and decanoic acid was the same as that reported in young Chen in blanc wines in this study. In unaged distillates, increased levels of ethyl lactate also exert a negative influence on distillate quality. Iso-amyl acetate, hexyl acetate, ethyl caproate, ethyl caprylate, n-butanol, octanoic acid, ethyl caprate and decanoic acid showed some positive correlation, whilst iso-butanol, ethyl lactate, acetic acid, acetaldehyde and ethyl acetate showed a significant negative correlation to three-year old distillate quality. Sensory descriptive analysis on selected good, average and poor quality distillates using the South African brandy aroma wheel showed that there are small differences in profile between the good and average distillates, there were however significant differences between the good and poor quality distillate profiles throughout maturation. After three years of wood maturation, the aroma profile of poor quality distillates can be characterised by prominent herbaceous and woody aromas, which are more intense than the fruity aromas. Good quality distillates contained characteristically intense fruity aromas. Volatile compound concentration differences were noted during the course of and after three years of wood maturation and in barrels of varying ages. Distillates matured in new block barrels exhibited significant differences in volatile and wood compound composition after three years when compared to remaining barrels used. The style classification of the three-year old potstill distillate was influenced by demographic and production factors and volatile compound composition, but not by the sensory quality of the distillates. In summary, vintage, region, cultivar, harvest time and choice of yeast strain have a significant influence on the volatile composition of brandy base wines, their unaged and three year old potstill distillates, which in turn affects the sensory quality of these products. These effects cannot be viewed in isolation as they jointly exert an influence on the composition and quality of these products. From a commercial perspective, this study has provided a valuable indication as to which production and demographic factors can influence the quality and style of potstill brandy. Thus, future brandy base wine intake should, as far as possible, take place in such a manner to allow base wines originating from the same cultivar or region or harvest time or combination thereof (and to a lesser extent yeast strain) to be received simultaneously at the distillery for distillation. / AFRIKAANSE OPSOMMING: Brandewyn produksie is 'n veelvoudige proses wat die volgende insluit: pars van druiwe, basiswyn fermentasie, verstoking, houtveroudering en versnyding. Binne hierdie stappe is verskeie faktore wat 'n invloed op die samestelling en resultate van die basiswyn, onverouderde en verouderde distillaat kan hê. Hierdie faktore sluit die volgende in: geografiese ligging, klimaat toestande van die streek van herkoms, wingerdboupraktyke, graad van rypheid, druifvarieteit, wynoes variasie, wynbou tegnieke, opberging van basiswyn voor distillasie, distillasie tegnieke, ouderdom en oorsprong van akkerhout vir die veroudering, asook tot watter mate die vat gerooster is. Die samestelling van geur in wyn en gedistilleerde produkte soos brandewyn is uiters kompleks. 'n Menigte samestellings kan deel vorm van die inhoud van die geur, en dit is raar dat 'n bepaalde verbinding alleenlik verantwoordelik is vir 'n kenmerkende geur. Weens die verskeidenheid van produksie faktore, aroma en smaak is volledige kennis van brandewyn ingewikkeld en kompliseerd om te verstaan. In kommersiële brandewynproduksie, maak standaard werksprosedures nie voorsiening vir aparte distillasie van basiswyn van verskillende produsente nie, en die vermenging van basiswyn van verskillende streke en produsente kom voor. Dit maak dit moeilik om te bepaal of die kwaliteit van die basiswyn of die distillaat na die neergelegde periode van houtveroudering, in werklikheid 'n beslissende indikasie op die kwaliteit van die verouderde produk is. Daarom is een van die doele van hierdie studie om te bepaal of daar meriete in is om brandewyn basiswyn van die verskillende produsente en streke apart te berg en te verstook. Dit is gedoen deur eerstens, die effek van demografiese en produksie faktore op die samestelling van brandewyn basiswyn te bepaal. Daarna, om die invloed van brandewyn basiswynsamestelling op die kwaliteit van onderskeidelik die onverouderde distillate sowel as die uiteindelike styl en kwaliteit van die 3 jaar oue houtverouderde potketel distillate, te bepaal. Vir hierdie doel, is vier potketels met 'n kapasiteit van 2000 liters elk geïsoleer en vir kommersiële skaal distillasies van 33 en 25 brandewyn basiswyne in 1999 en 2000, ondeskeidelik, by DisteIl Distillerdery, Worcester verstook. Die eksperimentele uitleg wat in hierdie studie gebruik is, ewenaar DisteIl se standaard verstokingsprosedures vir kommersiële brandewynproduksie. Chenin blanc en Colombar is die twee mees populêre druifvarieteite vir die maak van brandewyn basiswyn in Suid-Afrika. As gevolg van die kompleksiteit van die brandewyn produksieproses, is die eerste gedeelte van die studie gefokus op die Suid-Afrikaanse jong Chenin blanc wyne, met 'n oorheersende fermentasie geur. Die konsentrasie van iso-amyl asetaat, heksiel asetaat, etiel kaprilaat, etiel kapraat, 2-phenetiel asetaat en oktanoë suur was aansienlik hoër in wyne wat met goud en silwer medaljes bekroon is en neem aansienlik af met afname in kwaliteit kategorieë. Etiel laktaat vertoon die teenoorgestelde patroon. 'n Kwaliteit voorspellersmodel, gebaseer op die gedrag van 21 vlugtige komponente was opgestel. Die model het redelike akkuraatheid getoon op wyne van dieselfde oesjaar as waarop oorspronklik opgelei. Die model se voorspellingsakkuraatheid was aansienlik swakker toe dit vergelyk getoets is met wyne van 'n nuwe oesjaar. Die hoeveelheid oesjare, hoeveelheid wyne per oesjaar en die hoeveelheid verbindings gebruik in hierdie model sal die voorspellingsakkuraatheid beïnvloed. Sewe-en-twintig vlugtige komponente was gekwantifiseer in 33 en 25 brandewyn basiswyne, die onverouderde en 3 jaar oue distillate vanaf 1999 en 2000, onderskeidelik. Variasie ontledings (ANOVA) en klassifikasie en regressie ontledings (CART) ontledings wys dat oesjaar, streek, parstyd, keuse van kultivar en gisrasse In aansienlike invloed op die vlugtige samestelling van brandewyn basiswyne asook hul onverouderde en 3 jaar distillate het. Hierdie faktore, sowel as die vlugtige verbinding samestellings, beinvloed ook bevind die sensoriese kwaliteit van hierdie produkte. Basiswyne, onverouderde en 3 jaar oue distillate wat vanuit die De Doorns streek, wat hoofsaaklik tafeldruif kultivars is, is van In swakker kwaliteit as die ander streke. Produkte wat gemaak is van druiwe wat vroeg in die seisoen gepars is, was van beter kwaliteit. Die vlugtige geurkomponentsamestellings het tussen die basiswyne en distillate van die 1999 en 2000 oesjare verskil, ongeag of party van die monsters gedeeltelike of volledige appelmelksuurgisting ondergaan het. Gevolglik, die konsentrasie van kwaliteitaanwysende komponente mag van seisoen tot seisoen verskil. Die verhouding tussen die kwaliteit van die brandewyn basiswyne en die konsentrasie van n-butanol, iso-amiel asetaat, etiel laktaat, etiel kaprilaat, oktanoë- en dekanoë suur was dieselfde soos gerapporteer oor die jong Chenin blanc wyne. In onverouderde distillate, het verhoogde vlakke van etiel laktaat In negatiewe invloed op distillaat kwaliteit veroorsaak. Iso-amiel asetaat, heksiel asetaat, etiel kaproaat, etiel kaprilaat, n-butanol, oktanoë suur, etiel kapraat en dekanoë suur In positiewe korrelasie, terwyl iso-butanol, etiel laktaat, asynsuur, asetaldehied en etiel asetaat betekenisvolle negatiewe korrelasie met 3jaar oue distillaat kwaliteit bewys. Beskrywende sensoriewe analises op geselekteerde, middelmatige en swak kwaliteit distillate (gedoen deur gebruik making van die Suid-Afrikaanse Brandewyn Aromawiel) wys dat daar klein verskille tussen die profiele van goeie en middelmatige distillate is. Daar is egter aansienlike verskille tussen goeie en swak kwaliteit distillataat profiele regdeur die drie jaar verouderingsperiode. Na 3 jaar van houtveroudering kan die geur profiel van swak kwaliteit distillate uitgeken word aan kruid- en houtagtige geure, wat meer intens as die vrugagtige geure is. Goeie kwaliteit distillate het intense vrugagtige-aroma eienskappe. Vlugtige verbinding konsentrasie verskille is waargeneem gedurende en na die 3jaar houtverouderingsperiode in vate wat van ouderdomme verskil. Distillate wat in nuwe blokkies vate verouder is, vertoon aansienlike verskille in vlugtige en houtkomponent samestellings na 3 jaar wanneer dit met die, wat in die oorblywende ouer vate verouder is, vergelyk word. Die styl klassifikasie van die 3 jaar oue potketeldistillaat was deur demografiese en produksie faktore sowel as vlugtige verbinding samestellings beïnvloed, maar nie met die sensoriese kwaliteit van die distillate nie. In opsomming, oesjaar, streek, kultivar, parstyd en keuse van gisrasse het 'n aansienlike invloed op die vlugtige komponent samestelling van die brandewyn basiswyne, onverouderde en 3 jaar oue potketel distillate, wat weer op hul beurt die sensoriese kwaliteit van die onderskeidelike produkte beïnvloed. Die effek van hierdie faktore kan nie in isolasie gemeet word nie, aangesien dit gesamentlik die kwaliteit van die produkte beïnvloed. Van 'n kommersiële perspektief het hierdie studie 'n waardevolle indikasie gelewer van hoe produksie en demografiese faktore die kwaliteit en styl van potketelbrandewyn kan beïnvloed. Daarom word voorgestel dat toekomstige brandewyn basiswyn innames, sover as moontlik, voorsiening moet maak om wyne van dieselfde kultivar, uit dieselfde streek, parsseisoen inaggeneem, of kombinasie daarvan, met 'n mindermate die gisrasse in aanmerking geneem, gelyktydig vir verstoking by die distilleerderye ontvang word sodat hierdie wyne apart van wyne met ander bogenoemde variasies verstook en verouder kan word.

Thesis (MscAgric (Viticulture and Oenology))--University of Stellenbosch, 2007. / Regal Seedless is a white, seedless grape which has the potential to become a profitable cultivar for the table grape producer since it has the advantages of early season harvesting and inherently large berries. There is, however, a downside to this cultivar, namely the seasonal occurrence of an unacceptable, astringent taste. This negative taste affects the demand by local and international markets. The astringency perception is due to the presence of phenolic compounds. It is well known that the phenolic composition and concentration change during the ripening of the grape. Different postharvest treatments are applied to fresh fruit like persimmons to remove astringency. These treatments include the use of carbon dioxide, nitrogen and ethanol. The aim of this study was to determine the optimum maturity level for Regal Seedless where the phenolic concentration is the lowest and the astringent taste acceptable. The use of postharvest treatments to manipulate the taste and the phenolic content, were also investigated. The effect on other quality parameters like total soluble solids (TSS), pH and total titratable acidity (TTA) were also evaluated.

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 (MScAgric)--Stellenbosch University, 1992. / One microfiche copy / ENGLISH ABSTRACT: The possibility of harvesting grapes at an earlier stage of maturity, based on differences in glucose and fructose concentration which influence the sweetness of grapes, was investigated. Although differences between cultivars were found the extent was not such that a specific cultivar could be selected in order to harvest at a lower sugar concentration, but with the same sweetness. Certain characteristics of table and wine grape cultivars with respect to anatomical composition and skin penetration resistance (SPR) were also investigated in order to ascertain the extent to which grapes would resist external damage, and to what extent turgor and skin thickness contributed to SPR. Daily variances in SPR confirm that not only skin strength, but also the turgor of the grape berry contributed to SPR. Skin penetration resistance seems to be a good criterion of the extent to which cultivars would resist external damage, because it is based on the toughness of the skin and the turgor of the berry. / AFRIKAANSE OPSOMMING: Die moontlikheid van vroeer oes op grond van verskille in die glukose- en fruktosekonsentrasie wat 'n invloed op die soetheid van druiwe mag he, is ondersoek. Daar is gevind dat die verskille wat tussen cultivars voorkom nie van so 'n grootte-orde is dat 'n spesifieke cultivar geselekteer kan word ten einde by 'n laer totale suiker, maar by dieselfde soetheidsgraad, te kan oes nie. Verder is sekere eienskappe van tafel- en wyndruifcultivars t.o.v. anatomiese samestelling en doppenetrasieweerstand (DP\V) ondersoek om die moontlike weerstand teen eksterne beserings en die mate waartoe turgor en dopdikte 'n invloed daarop mag uitoefen, _vas te stel. Daaglikse variasie in DPW het bevestig dat die DPW nie alleen afhanklik is van dopsterkte nie, maar ook van die turgor van die korrel. Doppenetrasieweerstand blyk 'n goeie maatstaf te wees vir die mate waartoe cultivars weerstand hied teen sekere eksterne beserings omdat dit gebaseer is op dopsterkte en turgor van die korrel.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

La plaie tumorale est une infiltration par des cellules tumorales du tissu cutané, des vaisseaux sanguins et/ou lymphatiques. Ces plaies peuvent se présenter sous des aspects très différents accompagnés de symptômes variés. Outre les risques d'infection locale, les odeurs nauséabondes posent des problèmes récurrents d'isolement social, de difficultés conjugales et entrainent une sensation de dégout, de pourriture, voire de mort imminente. Elles influencent même le comportement médical. La colonisation bactérienne, les odeurs et les risques infectieux semblent intimement liés chez ces patients porteurs de plaie, dont l'immunité est le plus souvent affaiblie par l'administration de traitements anticancéreux. Ce projet a consisté à : 1) créer un fichier dynamique de données et prélever les patients porteurs de plaies tumorales, dans le cadre d'un travail de recherche clinique, 2) par une approche expérimentale personnelle et collaborative: caractériser la flore microbienne, la présence éventuelle de biofilm et les composés volatils des plaies, 3) analyser l'ensemble des données en mettant en évidence, si elles existent, les corrélations entre résultats des prélèvements et observations cliniques, 4) proposer de premières hypothèses, des pistes de solution, une adaptation des pratiques de soins.Une flore mixte composée de 54 bactéries différentes a été retrouvée sur les plaies et la présence de biofilm mise en évidence dans 35% des cas. 91 composés volatils ont été identifiés. Aucune infection n'a été relevée durant la période d'évaluation. Les conséquences de l'interactivité entre les bactéries, le biofilm et les composés volatils nous amènent à penser qu'il serait nécessaire de: 1) développer de nouvelles stratégies et topiques, 2) poursuivre les travaux sur le biofilm, 3) construire des projets en liens avec des psycho-oncologues et neuropsychiatres, 4) progresser vers la conception d'outils diagnostics et l'identification de biomarqueurs. / The malignant wound is an infiltration by tumoral cells of the cutaneous tissue, the blood and/or lymphatic vessels. These wounds can appear in different forms and and be accompagnied by various symptoms. Independently of the septic risk, the presence of nauseating odors induces social, family and conjugal difficulties, expressed mostly by disgust, a sensation of dirt or decay. It influences the medical behavior.Bacterial colonisation, odors and septic risks seem to be connected and mainly occur in patients who have a chronic wound and are immunodepressed by the anticancer therapies. This projetc [was] consisted in: 1) create a case report form and sample the malignant wound (clinical research), 2) characterize the microbial flora, the biofilm, and the volatile compounds with an experimental and collaborative approach, 3) analyse the results and the potential correlation between [the] laboratory's results and the clinical aspect of the wound, 4), propose potential solutions, hypothetis, and improvements of the clinical practice.A mixed flora, composed of 54 different bacterial types was identified; a biofilm was caracterized in 35% of cases. 91 volatile compounds were identified. No infection occurred during the evaluation period. The consequences of the interactivity of the bacteria, the biofilm and the volatils compounds suggest to: 1) develop new strategies and topics, 2) continue the research on the biofilm, 3) propose a research program with psycho-oncologists and neuropsychiatrics, 4) progress toward diagnostic tests conception and biomarkers identification.

Generation of hydrogen sulfide (H2S) is a common phenomenon from wastewater collection, transport, and treatment processes. Impacts of H2S emissions from wastewater include corrosion and reduction in the service life of wastewater infrastructure, odor nuisance in the community, and health impacts on wastewater operations and maintenance personnel (Neilsen, et al. WEFTEC 2006). Conventional odor control studies performed by municipalities to design their individual odor/corrosion control strategies largely depend on establishing a dilution to detection threshold (D/T) ratio and ascertaining the recognition threshold (R/T) for air samples collected from the study area. These conventional odor studies based on grab samples using R/T and D/T technique using a few days of data have a number of limitations and potentially lead to inaccurate conclusions. However, H2S emission studies using continuous air monitoring is expensive and time consuming. The objective of this research is to understand the feasibility of utilizing emission factors as a tool to predict hydrogen sulfide emissions from headworks of four different Jefferson Parish, Louisiana wastewater treatment plants (WWTP). Proposed model(s) developed for predicting H2S emission factors that depend on wastewater parameters should be convenient for the municipalities to use as the data required is monitored routinely. Use of H2S emission models should assist rapid identification of H2S emission hot spots, optimize H2S control strategies, predict potential health risks, prevent community odor nuisance, and ascertain infrastructure corrosion. This dissertation attempts to; i) develop a research methodology, ii) identify instruments required, iii) generate emission factor ranges and compare their sensitivity to wastewater parameters, iv) generate preliminary empirical emission models based on flow treated, population serviced and area served by a treatment plant for each sampling location and v) provide a roadmap for future research opportunities to refine the models generated as part of this dissertation. Key words: emission model, emission factor, emission ranges, hydrogen sulfide, odor control, air quality, wastewater treatment.

Hydrogen Sulfide is a corrosive, odorous, and hazardous gas that can cause issues for wastewater collection systems and treatment plants. When evaluating hydrogen sulfide concentrations it is important to consider the source, odor causing mechanism, and its level of toxicity. In this study, continuous hydrogen sulfide monitoring was performed for 8 locations within the New Orleans East Bank Wastewater Treatment Plant for a span of 5 months. Hot spots within the plant are located and data analysis is performed based on daily and hourly averages of hydrogen sulfide concentrations. The data was configured to show peak hydrogen sulfide concentrations at specific time intervals throughout the day.

Ce doctorat a pour objectif de contribuer à une meilleure compréhension du lien, plusieurs fois démontré, entre odeurs et couleurs. Il s’organise en 4 parties correspondant à 4 grandes études réalisées dans différents pays, la France, le Liban et Taiwan, ainsi que dans différentes régions au sein d'un même pays (Liban urbain, Liban rural). La première étude effectuée dans les trois pays avait pour objectif de démontrer l’impact de la culture sur la construction du lien odeurs – couleurs. Les résultats obtenus ont mis en évidence un effet significatif du lieu de résidence des participants sur la construction du lien mais aussi du rôle prépondérant de la « fonction de l'odeur » (alimentaire, cosmétique, industrielle, …). La seconde étude interculturelle entre la France et le Liban s’est intéressée plus spécifiquement à la méthodologie employée pour réaliser les tests odeurs – couleurs. En effet, dans la littérature, deux types de procédures sont généralement employées soit la présentation de couleurs physiques que le participant peut regarder soit l’absence de présentation de couleurs physiques et l’utilisation de noms de teintes (bleu, vert, rouge, …). La comparaison de ces deux méthodes a mis en évidence un effet de la procédure tout aussi important que celui de la culture et de la fonction de l'odeur sur l'association odeur-couleur. Les données ont aussi mis en évidence un réel pouvoir d’évocation olfactive des couleurs. Pour mieux, comprendre ce phénomène, nous avons réalisé une étude en IRMf. Cette troisième étude utilisant l'IRMf a montré que le pouvoir d’évocation olfactive d’arrangements abstraits de couleurs était différent de celui obtenu à partir de représentations visuelles figuratives colorées. Les processus cognitifs mis en œuvre lors d’une évocation olfactive à partir de couleurs sont plus complexes et multimodaux impliquant des processus olfactifs, émotionnels, visio-spatial, du langage ainsi que la mémoire. La dernière partie de ce doctorat s’est intéressé à mieux comprendre comment les processus émotionnels mis en évidence par IRMf pouvaient interférer avec la construction du lien odeurs – couleurs. L’étude a été réalisée en France ainsi que dans deux régions, rurale et urbaine, du Liban. Les résultats ont montré que l'affect associé à une odeur influençait le lien odeurs-couleurs mais surtout, que le choix préférentiel de certains affects était lié à la situation socio-économique et culturel du participant. Cette thèse est donc une contribution à une meilleure compréhension du lien qui unit odeurs et couleurs. Elle en a démontré la complexité avec un effet avéré de la fonction de l’odeur dans le pays, de la méthodologie employée ainsi que du lieu de résidence et du niveau socio-culturel du participant. Elle souligne cependant la nécessité d’une approche multidisciplinaire pour en comprendre encore plus précisément l’ensemble des rouages / This doctorate aims to contribute to a better understanding of the link, several times demonstrated, between odors and colors. It is organized in 4 parts corresponding to 4 major studies carried out in different countries, France, Lebanon and Taiwan, as well as in different regions within the same country (urban Lebanon, rural Lebanon). The first study carried out in the three countries aimed at demonstrating the impact of culture on the construction of the odor-color link. The results obtained revealed a significant effect of the participants' place of residence on the construction of the link but also the predominant role of the "function of the odor" (food, cosmetics, industrial ...). The second intercultural study between France and Lebanon focused more specifically on the methodology used to carry out odor - color tests. Indeed, in the literature, two types of procedures are generally used: presentation of physical colors that the participant can see or absence of presentation of physical colors and the use of color names (blue, green, red, ...). The comparison of these two methods revealed an equally important effect between the procedure, the culture and the function of the odor on the odor-color association. The data also revealed that colors have the capacity of olfactory evocation. To better understand this phenomenon, we performed an fMRI study. This third study using fMRI showed that the olfactory evocation power of abstract color arrangements was different from that obtained from colored figurative visual representations. The cognitive processes involved in an olfactory evocation from colors arrangement, is more complex and multimodal involving olfactory, emotional, visio-spatial, language and memory processes. The final part of this Ph.D. examined how emotional evidenced by fMRI could interfere with the construction of the odor - color link. The study was carried out in France as well as in two rural and urban areas of Lebanon. The results showed that the affect associated with an odor influenced the odor-color link, but above all, that the preferential choice of certain affects was linked to the socioeconomic and cultural situation of the participant. This thesis is therefore a contribution to a better understanding of the link between odors and colors. It has demonstrated its complexity with a proven effect of the odor function in the country, the methodology used and the place of residence and socio-cultural level of the participant. However, it stresses the need for a multidisciplinary approach to understand even more precisely the whole workings