Analysis On Factors Of Higher Alcohols' Formation During The Process Of Wine Brewing

Five different yeasts which are from Yun nan grape-producing areas to discuss the tolerance of yeast are used as the experimental materials in this paper, including B-4,D-1,D-2,Q-42-2,Q-50-2. We screen and purify them, and then test five different yeast for different layers of sugar content, alcohol, acidity, sulfur dioxide, and we have tested the strains'tolerance in these factors. The fermentation results show that the strain Q-50-2 has the most tolerance capacityWe studied the changing trend of sulfur dioxide on the premise of different substrate sugar content during the alcohol fermentation . The contents of free sulfur dioxide and total sulfur dioxide were determined at the regular time everyday during the alcohol fermentation , and analyzed according to the determination rules of GB . The result shows that free sulfur dioxide was consumed very fast from initial contents 100mg/L to 7mg/L around , at the beginning of the fermentation , then tended to a constant ; the total sulfur dioxide had no significantly changed , from initial contents 100mg/L to 85mg/L around , in the whole process , there were not obviously changes about total sulfur dioxide .The environmental factors including inoculum concentration of yeast ,α-amido nitrogen concentration in grape musts, fermentation temperature,Adding sugar ,SO2 concentration and pH of the musts were tested and were demonstrated in relation to the content of higher alcohols produced during alcoholic fermentation in grape wine of Cabernet Sauvignon.And the results confirmed that a remarkable variability of higher alcohols content occurs in the production brewed by the different yeast strains.For single strain ,different inoculum concentration generate different amount of higher alcohols in the vinification. Increasing the inoculum concentration of Q-50-2 in the grape musts properly led to lesser higher alcohols content too. The results were also show that total higher alcohols decreased when addition simple organic amino nitrogen or inorganic amino nitrogen at a range of 180～190mg/Lα-amino nitrogen in the grape musts . The lower fermentation temperature and lower pH of grape juice give rise to the decreasing the amount of higher alcohols . Adding sugar twice during fermentation could make higher alcohols produce lower than adding sugar once;If the total SO2 concentration is more than 80mg/L,fermentation will lag obviously,and higher alcohols produced are obviously higher.