Proceedings Volume 2010 (format .pdf) - SimpBTH

THE INFLUENCE OF THE CHEMICAL COMPOSITION OF THEGROWING ENVIRONMENT OVER THE ALCOHOLICFERMENTATION OF THE WINE YEAST SACCHAROMYCES BAYANUSGASPAR, E. 1 , OPREAN, L. 1 , TITA, O. 1 , TITA, M. 1 , LENGYEL, E. 1 , TUSA, C. 11 University „Lucian Blaga” of Sibiu, Faculty of Agricultural Sciences, Food Industry and EnvironmentalProtection, Sibiu, RomaniaKey words: must malt, fermenter, Saccharomyces bayanusABSTRACTIn the wine making technology they use more and more the selected yeasts so that thealcoholic fermentation has an increased efficiency and to be produced faster. The yeast cell has theproperty of fermenting the glucides and oligoglucides due to its enzymatic equipment. According tothis, the yeasts must have superior biotechnological properties, and the used yeasts to have the abilityto multiply as fast as possible. The yeasts which were selected for this study were isolated from inlandgrapes and were subject to the alcoholic fermentation in the Sartorius bioreactor which was equipedwith sensors for: temperature, biomass, CO 2 and oxigen. The three yeast strains of Saccharomycesbayanus (SB1,SB2,SB3) were monitored through the biomass accumulation which was resulted fromalcoholic fermentation in standard enviroment and also in vitaminized and minerals enrichedenviroments. The study pointed the strain with most biotechnological properties so that this strain canbe used for industrial processes.INTRODUCTIONIn wine making technology, the used yeasts form the base agent whichleads to physio-chemical, bio-chemical and microbiological processes which areimplied in grapes must transformations. The yeasts can be found usually in soiland, by the means of physical and biological factors, they end up in vine, strainsand grapes. The wasps and the bees, vinegar flies (Drosophilla melanogaster)provide the transfer of the yeasts from the soil to the bunch and contribute informing of their life cycle.The climatic conditions play an important role in thequality and the quantity of the the yeasts on the grapes The grapes are the rawmaterial in the wine making technology, and also for the obtaining of distilledproducts, juices or must.Taking into account the big amount of yeast species which are in thegrapes must and also the diversity of the actions, there has been questioned theisolation of the most active yeasts, which are called selected yeasts. In the case ofusing these yeasts, there is the advantage of increasing the speed of thefermentation, of the conversion of sugar into alcohol in an efficient way.In order to select the yeasts for the wine making technology, the followingproperties are considered: fermentation speed, alcoholic power, resistance to SO 2(sulfitoresistance), the endurance to low and high temperatures, tolerance to highconcentrations of sugar (osmotolerance), behavioural in the presence of organic153