Aroma Producing Yeast Strain Screening,Identification For Rice Aromatic Chinese Spirits And Research On Ester Production Law Of It

Rice aromatic Chinese spirits is one kind of the Chinese wine which had four types according to flavor,and had several advantages,such as profound cultural background and huge consumer market.However,the shortcoming is that the aroma is thin,lack of taste.According to former studies,aroma-producing yeast has unique aroma-producing characteristics,which can be flavored with traditional fermented foods,and has been widely applied in liquor,yellow rice wine and fruit wine.To fit different type of flavor,the yeast used for brewing is different.So far there is little studies aimed at improving the flavor of Rice aromatic Chinese spirits.In this study,we isolated yeast with high quality Aroma-producing yeast with strong aroma-producing ability,unique aroma and good fermentation performance from apple,grape,fermented glutinous rice wine,Starter,sour dough.In order to get the best flavoring yeast strains of Rice aromatic Chinese spirits,the aroma-producing yeasts were applied to brewing,and comprehensively evaluate the sensory index and flavor substance content of the samples through principal components analysis method.In addition,the growth characteristics and ester production characteristics of the best strains were analyzed.The main contents of the paper are as follows:(1)By sniffing analysis,aroma classification,determination of aroma intensity,determination of total ester content and fermentation initiation in 48 h,20 strains of aroma-producing yeasts were screened separately from apple,grape,fermented glutinous rice wine,Starter,sour dough and pickles.By 26S rDNA sequence analysis,20 aroma-producing yeasts were determined to be:6 strains of Hanseniaspora uvarum 1 strain of Hanseniaspora opuntiae,3 strains of Saccharomyces cerevisiae,8 strains of Wickerhamomyces anomalus and 2 strains of Wickerhamomyces anomalus.(2)20 aroma-producing yeasts and Angel aroma-producing yeast are mixed respectively with purebred rhizopus to make new aroma-producing starter.Take wine-producing Starter as a contrast,samples were subjected to appearance analysis,test of rice and determination of saccharification power and fermentation force.The results showed that the starters don’t produce spores,no sour smell,the lump is tight,unique flavor,the saccharification force reached more than 800U,but the fermenting power is weak.Liquor brewing process requires the aroma-producing starter with 1:1 mixed.To comprehensively analysis of 16 indexes of Rice aromatic Chinese spirits including sensory evaluation and flavor substance content with principal component analysis.The comprehensive value of each sample was calculated,in which the comprehensive value of the control sample was 0.906。Among aroma-producing starter,only HF13-4 had a higher comprehensive value than the control sample,its comprehensive value is 1.908.Further analysis of the correlation between the comprehensive value and the sensory evaluation,result shows that a very significant positive correlation between the comprehensive value and the sensory score(P<0.01).It was determined that HF13-4 could improve the flavor of Rice aromatic Chinese spirits.The verification test results showed that:after adding HF13-4 aroma-producing starter,the content of esters andβ-phenylethanol increased,the content of some alcohols decreased,the aroma intensity of the finished wine increased,while the special flavor of rice wine was preserved,and the taste was more mellow and sweet.In conclusion,HF13-4(Hanseniaspora uvarum)has remarkable effects on improving the flavor of Rice aromatic Chinese spirits(P<0.05).Analyze and discuss the growth characteristics and aroma-producing characteristics of HF13-4.Determine the optimum growth temperature of HF13-4 at 30℃;the optimum pH is 5.5;the tolerance to ethanol is moderate,and the tolerable concentration is 8%.The most suitable ester-producing medium was Migu juice medium.The optimum culture method was anaerobic culture.The amount of yeast added was 1.2%.The optimal temperature for producing ester was 32℃,and the optimal pH for producing ester was 5.5.The most suitable ester-producing medium was rice starter liquid.The optimum culture method was anaerobic culture.The amount of yeast added was 1.2%.The optimal temperature for producing ester was 32℃,and the optimal pH for producing ester was 5.5.Second days after HF13-4 fermentation,adding saccharomyces cerevisiae increased the best flavor has the best fragrance effect in the process of mixed bacteria fermentation.