Screening Of Ester-producing Yeast From Xiaoqu Of Soybean-flavor Liquor And Its Application

The soy flavor liquor is high produced in the China’s Pearl Delta area,named by the typical soy flavor,which has the unique southern C hina characteristics.Soy flavor liquor produce with peculiar techniques,uses rice as raw material and Xiaoqu as saccharifying leaven,which are made of rice,soy beans,mud,leaves and active dry yeast.The soy flavor liquor is produced with the method of saccharification and fermentation contemporary in liquid.Because of the special producing techniques,the esters,especially ethyl acetate was lower in the liquor and had great difference in flavor with other liquor.Therefore,screening of ester-produce yeast and applied research on fermentation process are significant to improve the quality of soy flavor liquor.This paper describes the separation,purification,and screening of high ester-produced yeast from Xiaoqu,as well as applications on production of soy flavor liquor.The main contents and results are as follows:The Xiaoqu of soybean flavor was used as experimental materials in this experiment.10 strains of yeasts were separated,using the methods of enrichment,separation and purifying.6 trains of target yeast strains with stronger flavor-produce and alcohol-produce abilities were verified among them,by observation of bacterial colony and cellular morphology.After preliminary screening,secondary screening,pilot test and the analysis as well as comparison of ethyl acetate,alcohol,flavor-producing ability,it found that yeast Y1 had higher ethyl acetate and ethyl lactate production capacities.The content of ethyl acetate in yeast Y1 was 1.36g/L and the ethyl lactate was 1.14g/L.In production performance test,the content of ethyl acetate had improved 36.5%,under coefficient effect of yeast Y1 and active dried yeas and there’s no obvious decrease of liquor yield during production.The mouthfeel of liquor had notable improvement by sensory evaluation,therefor,yeast Y1 was selected as optimum strain.To enhance the applicability of high ester-produce yeast Y1 on production,the techniques need to be optimized.The results showed that,on the base of specific addictive amount of saccharification and fermentation starters,the optimum techniques of yeast Y1 were: inoculum size 1.0%,active dried yeast 0.08%,and 14 d fermentation time.Under these production conditions,the production content of ethyl acetate was 0.44g/L,the content of ethyl lactate was 0.68g/L.The content of ethyl acetate had improved 46.5%,while the alcohol content remained.The product had rich rice flavor,mellow mouthfeel and strong style by sensory evaluation.