Research On The Fermentation Characters Of Fine Yeast Strains

Yeast is the main microorganisms during wine-making. Different yeasts can give different types of wine flavors. Winemakers are recently focusing on the important contribution of natural yeast to make the original wine, or in combination with commercial yeast. The wines that co-fermented by natural yeast with commercial yeasts together have rich taste and aroma, unique features as well. In this paper, two natural yeast strains ZYFJQ and YQY, separated from grapeberry, were used to produce dry red wine by using single strain or in combination with commercial yeasts RC212 and D254, with the raw grape harvested from Yantai grapery. The mainly purpose of this study is to select the best combination and to evaluate the influence of selected yeast strains on the physic-chemical indexes, the sensory quality and aroma component of the wine.Sensory evaluation showed that the co-fermented wine was rich in aroma flavors. D254+ZYFJQ is the best combination for wine with Gernischt grape, the wine has purely pleasant fruity and alcohol aroma, and cultivar's typical flavor expresses very strong. Aroma components by GC-MS analysis showed that fermentation aromas were substantially retained, a number of super-alcohol ester was examined after ageing, and super-alcohol ester could balance better with varietal aroma. The combination of RC212+D254 +YQY produced 38 components of aromas, with thicker alcoholic bouquet and more harmonious taste.RC212+ZYFJQ is a better combination for grape Cabernet Sauvignon, the wine has fruity taste and aroma complexity, finess and purity. Aroma analysis showed that a large number of complicated super-alcohol, except for fermentation aroma, were detected after ageing. This is good for the formation of original wine typicality. The combination of RC212+D254 +YQY produced 31 components of aromas in wine, with more harmonious taste. D254+ ZYFJQ is a better combination for making Yantai original wine, its balance between physic-chemical indexes and aroma is more prominent.The experiment was conducted to examine the natural yeasts impact on Gernischt wine quality by different inoculation methods (different time, seed ratio of strain, and order). The results showed that the combinations which first inoculated strain ZYFJQ produced more rich and smooth mouthfeel. 15# is the best one, which firstly inoculated ZYFJQ and then added an equal volume of D254 after 48h. 31 aroma components were determined from the wine sample of 15#, 1,6-dihydrocarveol and nerolidol were detected for the first report. The longer time ZYFJQ fermented alone, the more aromas it produced, but inoculation ratio of ZYFJQ has no obvious influence on wine aroma.