Isolation and aromatic-producing characteristics of yeasts from stacking fermented grains of sesame-flavor Baijiu
In order to explore the yeast resources in the production process of sesame-flavor(Zhimaxiangxing)Baijiu,the yeasts in stacking fermented grains were counted by WL solid medium.Using the fermented grains samples with a large number of viable yeasts as the separation source,the yeasts were isolated by dilution coated plate method,and identified by morphological observation and molecular biology techniques,and the volatile flavor components in the fermented liquid were determined by headspace solid phase microextraction(HS-SPME)and GC-MS.The results showed that the varieties and quantities of cultivable yeasts were the most in fermented grains stacking for 40 h,a total of 9 types of yeasts were isolated and identified at this stage,which were Pichia kudriavzevii,Pichia membranifaciens,Pichia fermentans,Pichia exigua,Torulaspora delbrueckii,Saccha-romyces cerevisiae,Starmerella sorbosivorans,Starmerella apicola,Wickerhamomyces anomalus.Among them,S.sorbosivorans was isolated from Baijiu brewing environment for the first time.The aromatic production of the 9 types of yeasts had both commonness and characteristics,and all could metabolize and produce alcohols,esters,acids,aldehydes and ketones,phenols,pyrazines,and other substances,among them,the proportion of alcohols,esters and acids was as high as 90%-98%.It could be seen that there were abundant yeasts resources in the stacking fermented grains of sesame-flavor Baijiu,and laid a foundation for the special application of strains in Baijiu production.
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