Screening And Fermentation Characteristics Of Excellent Indigenous Saccharomyces Cerevisiae In The Eastern Foothill Of Helan Mountain

Wine fermentation is a series of biochemical reactions.Saccharomyces cerevisiae plays a dominant role in wine brewing and is one of the most important factors affecting wine quality.At present,the widespread use of commercial yeasts has led to no prominent characteristics of wine quality and serious homogenization.Indigenous S.cerevisiae has good adaptability to the physical and chemical conditions and microbial ecology of grape juice,and can coordinate the natural flora in grape must faster,which is conducive to highlighting the unique characteristics of wine terroir in the producing area.Therefore,it is significant to explore excellent indigenous S.cerevisiae in the wine producing areas in the eastern foothill of Helan Mountain in Ningxia.In this study,the basic physiological characteristics of 168 indigenous S.cerevisiae strains obtained from three sub-producing areas Yinchuan.Qingtongxia and Yuquanying in the eastern foothill of Helan Mountain were screened,and several excellent indigenous S.cerevisiae strains were selected for Cabernet Sauvignon wine brewing test.The main results are as follows:(1)The fermentation abilities of 168 indigenous S.cerevisiae strains were tested,and 107 yeast strains with fast fermentation speed and strong fermentation activity were selected.According to the tolerance tests of ethanol,high glucose,low pH and SO2,12 indigenous S.cerevisiae strains were rescreened,which could adapt to the living environment of 13%ethanol.350 g/L glucose,pH 1.0 and 250 mg/L SO2.Four indigenous S.cerevisiae strains with low H2S production were screened by H2S production ability test.According to the growth curve determination test,four strains of S.cerevisiae YCE8,QTX-D17,QTX-D7 and YQY-E18 were selected,which showed strong yeast starter ability,good tolerance,outstanding acid resistance,rapid reproduction rate and vigorous growth.(2)Four indigenous S.cerevisiae strains and three commercial yeast strains were used for Cabernet Sauvignon wine brewing.It was found that the wine samples fermented with indigenous S.cerevisiae strains QTX-D17 and QTX-D7 had the highest overall score through sensory evaluation,and the wine body showed the characteristics of comfortable taste,mellow coordination and long aftertaste.The wine fermented with QTX-D17 had the highest contents of ethanol,tannin,total phenols and anthocyanins,followed by the wine fermented with QTX-D7,which promoted the overall flavor of the wine.The wine brewed with indigenous S.cerevisiae YC-E8 has the highest glycerol content,and glycerol helps to round the wine taste and enhance the flavor.The physical and chemical indexes of wine samples fermented with indigenous S.cerevisiae YQY-E18 and other strains were up to the national wine standards.Therefore,all these four indigenous S.cerevisiae YC-E8,QTX-D17,QTX-D7 and YQY-E18 showed good wine brewing characteristics.(3)The aroma components of Cabernet Sauvignon wine fermented with different S.cerevisiae were determined by sensory evaluation and GC-MS.The results of aroma evaluation showed that the aroma intensity of citrus and berries in Cabernet Sauvignon wine fermented by indigenous S.cerevisiae QTXD7 was higher than that of other strains,and the main aroma compounds included diethyl succinate,ethyl decanoate.ethyl caprylate,ethyl caproate.ethyl acetate and other esters,which gave the wine rich and complex coconut,rose,strawberry,apple and other flower and fruit aroma.The aroma intensity of floral and spicy flavors in Cabernet Sauvignon wine fermented by indigenous S.cerevisiae QTX-D17 was higher than that of other strains,and the main aroma compounds included phenethyl acetate and ethyl 2hexenoate,which gave the wine a pleasant floral and spicy aroma.The content of phenethyl acetate was significantly higher than that of other strains.Ethyl 2-hexenoate was a strain-specific aroma compound,which only detected in wine samples fermented with QTX-D17.Therefore,the two indigenous S.cerevisiae QTX-D7 and QTX-D17 performed better,and the aroma of fermented Cabernet Sauvignon wine was richer.In summary,according to the fermentation characteristics of Cabernet Sauvignon wine and the influence of wine aroma,two excellent indigenous S.cerevisiae QTX-D17 and QTX-D7 were finally screened out,which had the best overall performance on the quality of wine,and had the potential to brew characteristic wine in Ningxia producing area.The study provided a theoretical basis for improving the quality of wine in this producing area.