Study on Variation of Microbial Community and Comparison of Two Fermentation Technologies in Making Wine by Defective Jujube

In this research,defective jujube was used to produce wine with two different fermentation processes.One technology was called direct fermentation technique,in which jujube was used for fermentation directly without steaming treatment.And in the other technique,jujube was steamed before fermentation.Microbial flora change was studied during fermentation process of jujube in the first technique.Several quality parameters of the wine produced by the two methods were compared,which include the content change of phenol in the fermentation process,the contents of alcohol,Vc,methanol,and esters in the final product.The results showed that the main microbial species in jujube after harvest were mold and E.coli.On the third day of fermentation,the amount of E.coli reduced to less than 0.03 MPN/mL.On the sixth day of fermentation,mold could not be detected.At the end of the fermentation,the main microorganisms in the wine were yeast and a small quantity of lactic acid bacteria and acetic acid bacteria.The contents of alcohol and Vc in the wine produced by direct fermentation technique were 8.9% and 45.8 μg/g.And the contents of them in the wine made by the second technology were 7.8% and 47.7 μg/g.The contents of polyphenol,ethyl acetate,ethyl lactate,and ethyl caproate in the wine produced by direct fermentation technology were higher and the content of fusel oil was lower than that produced by the other technique.The contents of methanol in the wine produced by both the fermentation technologies were lower than 0.4 g/L which was the maximal value regulated by Chinese National Standard.So,the property of wine produced by direct fermentation technique was better than that produced by another technique.