Screening And Application Of Ester-Producing Yeast From Fen-Flavor Chinese Baijiu

Fen-flavor Chinese Baijiu has a unique flavor style and natural fragrance.Its distiller's yeast was fermented in solid-state ground cylinder by adding grain materials and core fungi,and distilling out liquor.Esters,as the main aromatic substances in liquor,play an important role in the formation of liquor flavor and aroma,and are the main characteristics that distinguish them from other distilled spirits.In this paper,the optimum conditions for the synthesis of ethyl acetate were optimized by studying the growth and fermentation characteristics of high yield ethyl acetate yeast.The main contents and results of the study are as follows:1.Screening of strains producing ethyl acetate.In this experiment,12 strains of yeast were isolated from the distiller's yeast of a winery,and then the ethyl acetate yield and CO2 weightless yield were determined by liquid fermentation.Four yeasts of producing ethyl acetate were screened out: Y6,Y36,Y45 and Y46.The yields of ethyl acetate were 406.19 mg/L,472.81 mg/L,422.68 mg/L and 832.64 mg/L,respectively.2.Identification and characterization of high ester yeast.The growth curve of four strains in liquid culture and the curve of ethyl acetate synthesis were analyzed.The results showed that the four strains reached the maximum growth at 36 h and the absorbance value of the bacterial suspension was closed to 1.The results show that the yeast entered the logarithmic growth period after 36 h in liquid culture.Further by analyzing ester production curve shows that in the process of liquid culture,the yield of ethyl acetate of strain Y46 reached the maximum at12 h fermentation,836.24 mg/L,significantly higher than that of other three bacteria,and the formation rate of ethyl acetate is higher.The dominant strains with high ethyl acetate yield were screened,then the yield of ethyl acetate decreased gradually in the later stage of the experiment.The molecular biology identification of the abnormal PichiaPichia anomala.3.Optimization of ester-producing conditions for high yield ethyl acetate yeast.Through single factor and response surface analysis,the optimum conditions for ethyl acetate production by yeast Y46 in liquid culture were determined as follows: fermentation temperature,28?,the inoculation quantity,5%,fluid volume,35 m L/ 50 m L.Under these conditions,the maximum amount of ethyl acetate produced by strain Y46was(1045.27±55.03)mg/L.The results provide a theoretical basis for the application of ethyl acetate-producing yeast in the fermentation of distiller's yeast.