Optimization Identification And Fermentation Characteristics Of Saccharomyces Cerevisiae In Zhejiang Province

Wine is a typical traditional fermented beverage with strong regional and social and cultural connotations.Product innovation is an important source of their competitive advantage in the market.It is necessary to screen high-quality native wild yeast.In this paper,207 strains with typical yeast characteristics were isolated from fresh grape fruits,root soil and mash of traditional wine brewed by local farmers from four urban vineyards in Zhejiang Province.The 207 strains of yeast isolated and purified were screened for four levels of fermentation ability,tolerance,basic physiological characteristics and simulated fermentation.In the first-level screening fermentation ability test,165 strains of yeast with strong fermentation ability passed;In the screening of tolerance screening,a total of 43yeast strains with strong comprehensive tolerance passed;in the third-level screening,a total of 5 yeasts with comprehensive basic physiological characteristics passed;in the fourth-level simulated fermentation,by monitoring the wine fermentation process The proportion of the yeast and the sensory evaluation after the fermentation is finished.Finally,SE1 and HF2,two local yeast strains with the highest sensory evaluation scores and strong comprehensive fermentation performance,can be fermented within 24 hours,and the strains have comprehensive tolerance.It is excellent in basic characteristics test,SE1alcohol resistance is between 15%（v/v）and 18%（v/v）,SO₂ concentration is above420 mg/L,high sugar resistance is above 45%,low p H 2.2,45℃high temperature resistance,high temperature resistance 9℃～12℃low temperature;HF2 alcohol resistance above 20%（v/v）,SO₂ resistance above 420 mg/L,high sugar resistance above 60%,low p H resistance between 2.2～1.6,42℃high temperature resistance,9℃～12℃low temperature;the two indigenous yeasts are medium and high alcohol-yielding,low-and medium-yielding hydrogen sulfide yeast,medium ester yeast,and low-yielding foamy yeast.The local yeast SE1 and HF2 were selected to ferment Cabernet Sauvignon grapes,and two kinds of commercial saccharomyces cerevisiae were used as controls to compare and analyze the fermentation effect through physical and chemical indicators,aroma components and sensory evaluation.The residual sugar of the liquid is below 4g/L,the total acid is between 6.304 g/L,and the alcohol content is 14.8%（v/v）～15.7%（v/v）.The aroma in different wines was determined by GC-MS mass spectrometry.It was found that the types of aroma substances in Cabernet Sauvignon fermented with native yeasts HF2 and SE1 were at most 70 and 62,respectively,and the aroma substances in Cabernet Sauvignon fermented by commercial yeast were 51 and 57,respectively.The aromatic substances of the brewing liquor produced by the yeast of HF2 are higher than those of the control bacteria;in the sensory evaluation of the wine,the brewing liquor of HF2 is clear and translucent,the fruit aroma is rich and complex,the structure is strong,and the aftertaste is long.It has the typical flavor of Cabernet Sauvignon,and the score is 92.67The best local Saccharomyces cerevisiae HF2 was selected.Therefore,HF2 is the best native yeast selected in this experiment and can be used in commercial winemaking.It is preferred that the native yeast SE1 and HF2 have been classified by WL identification and physiological and biochemical identification,and the identification result is Saccharomy cescerevisiae.