Yeast Population Analysis In The Fermentation Process Of Dry Red Wine In Yantai

Yeasts are the main microorganisms during winemaking,and has an important effect on wine quality,especially on the formation of characteristic wine. Yantai is one of main viticulture areas and production region of characteristic wine in China. Studies on the composition and dynamic change of microorganism in the fermentation process are beneficial to display positive action of local yeast effectually.117 yeast strains isolated from grape skin and fermentation liquor of dry red wine of Yantai in the paper are divided into 8 types according to their cell shape,cultural characteristic and colonial morphology on Wallerstein Laboratory Nutrient Agar. The typical strains of 8 types are identified based on the 26S rDNA D1/D2 domain sequence analysis, 8 species belonging to 6 genera are classified as: Saccharomyces cerevisiae,Pichia kluyveri,Hanseniaspora uvarum,Hanseniaspora occidentalis,Issatchenkia occidentalis,Issatchenkia orientalis,Lodderomyces elongisporus,Rhodotorula mucilaginosa,their ratios are 70.0%,7.7%,9.4%,0.9%,8.5%,1.7%,0.9%,0.9% respectively. The results showed that there existed abundant yeast resources in fermentation process of Yantai dry red wine.21 yeast strains with high fermentation capacity are screened out from 117 yeast strains by Durham tube method, then 5 yeast strains with good resistance and aroma are obtained by resistance evaluation. The alcohol fermentation result of 5 yeast strains shows that the alcoholicity of strains SL9-1 and SL8-1 is higher than commercial yeast strain RC212, but the alcoholicity of strain SS1-5 is 0. Strain SS1-5 may be used for bread baking and non-alcohol beverage because of its thick aroma. The results of RAPD analysis showed that the amplified bands of 4 yeast strains are same, displaying they belong to the same gene type.And their amplified bands are different from RC212 apparently, suggesting they are fine natural yeasts.The inoculating fermentation and natural fermentation are carried out using Cabernet Sauvignon and Cabernet Gernischt grape for studying the relativity between microorganism composition and physic-chemistry index of fermentation wine in the fermentation process. The results showed that the physic-chemistry index of different grape fermentation wine have similar trend during inoculating fermentation process,while the physic-chemistry index of same grape fermentation wine have different trend during different fermentation process. In inoculating industrial fermentation process, yeast species number are gradually diminishing and Saccharomyces cerevisiae play a dominant role; in natural fermentation process Hanseniaspora uvarum and Hanseniaspora occidentals are initial yeasts, while Hanseniaspora uvarum and Saccharomyces cerevisiae exist in whole fermentation process.