Study And Screening Of The Yeast From The Natural Fermentation Of Brier Grape Residues

This research started from isolating fifteen strains of yeasts from the residue of naturally fermented brier grapes to obtain a better strain of yeast through primary and secondary screening. Then its growth, tolerance and properties of fermentation have been studied. The main results are as follows:For designing this research, initial fermentation rate, fermentation smell and fermentation rate were assigned as preliminary screening indicators to screen nine strains of yeasts with tag J2, J5, J6, J7, J8, J12, J13, J14, J15. Using different kinds of pure yeasts for wine making with Angel Yeast as a control, the better strain yeast, J2, has been found through rescreening according to the physical and chemical indicators of final products. Based on the observation of the growth of yeast J2 on WL nutrient agar medium and the morphological identification, preliminary determination has been developed that yeast J2 belongs to Saccharomyces cerevisiae.According to the studies on yeast J2, the growth curve of brier grape yeast has been measured, and the optimum condition for growth is under pH 5.0 at 30℃. For designing tolerance test, tolerability of yeast J2 has been studied for obtaining the tolerance parameters:20% vol alcohol tolerance,40℃ heat resistance,50% high sugar tolerance, and pH 2.0 high acid tolerance. The tolerance of yeast J2 is better than Angel Yeast which can be bought on the market. By means of studying on the fermentation properties of yeast J2 to measure the fermentation rate, there was no significant difference between Angel Yeast and yeast J2. However, the comprehensive tolerance ability of yeast J2 is outstanding compared to Angel Yeast. In addition, yeast J2 is more suitable for brier grape wine producing.