Effects of temperature and yeast strain on ethanol fermentation kinetics in the production of wine from emir grapes

ABSTRACTMSC THESISEFFECTS OF TEMPERATURE AND YEAST STRAIN ONETHANOL FERMENTATION KINETICS IN THE PRODUCTION OFWINE FROM EMIR GRAPESAysun ŞENERDEPARTMENT OF FOOD ENGINEERINGINSTITUTE OF NATURAL AND APPLIED SCIENCESUNIVERSITY OF ÇUKUROVASupervisor : Prof. Dr. Ahmet CANBAŞYear: 2005, Pages: 87Jury : Prof. Dr. Ahmet CANBAŞAsst. Prof. Dr. M Ümit ÜNALAsst. Prof. Dr. Ahmet PINARBAŞIThis research was undertaken to investigate effects of temperature and yeast strainon ethanol fermentation kinetics in the production of wine from Emir grapes grown inNevşehir-Ürgüp region.Ethanol fermentation was carried out at 18ºC and 25ºC using two different yeaststrain (`Zymoflore VL1? and `Uvaferm CM?) in grape must. The samples taken at 12-hourtime interval were analysed for live yeast, biomass, sugar and ethanol.Specific growth rates at 25ºC were found to be higher than those at 18ºC. In terms ofspecific growth rates, no difference was found at 18ºC, while specific growth rate of`Uvaferm CM? at 25ºC was higher than that of `Zymoflore VL1?.Growth-associated product formation by `Zymoflore VL1? at 18ºC was higher thanthat of `Uvaferm CM?, while cell and biomass yields were lower. In addition, specific deathrate of `Zymoflore VL1? at 18ºC was found to be lower than that at 25ºC.Organoleptic evaluation showed that the wines produced at 18ºC were morepreferred. The wines produced by using Uvaferm CM at both temperatures had higher scorethan those produced by Zymoflore VL1.KeyWords: Kinetics, temperature, alcoholic fermentation, Saccharomyces cerevisiaeII