Characteristics of Non-Saccharomyces in Dough Fermentation for Steamed Bread Making

In this study,the characteristics of two kinds of non-Saccharomyces yeast,Wickerhamomyces anomalus Y13 and Torulaspora delbrueckii Y22 isolated from Jiaozi,in dough fermentation in single and co-culture and their effects on steamed bread quality were studied.The results showed that Y22 had the highest fermentation speed in the initial 1 h of dough fermentation,and it had no significant difference with the dough fermented by co-culture after 1.5 h.The fermentation capacity of Y13 was the lowest in the whole process.The content of reducing sugar in the Y22 fermented dough increased gradually during the dough fermentation,and in the Y13 and the mixed yeast fermented dough,it increased in first 8 h and then decreased,indicating that the sugar content was not the limiting factor of the fermentation capacity of the yeast and was related to the yeast's own characteristics.The pH of dough inoculated with Y22 in the first 12 h was significantly lower than that of Y13,indicating that acid production level by Y22 was higher than that of Y13.After 24 h,the number of Y13 cells in the dough fermented by mixed yeast showed no difference from that by the single Y13 culture,but the cells of Y22 was significantly less than that of the single Y22 fermented dough,indicating that the growth of Y22 under the mixed yeast fermentation system was partially inhibited by Y13.The specific volume of steamed bread made by Y22 and mixed yeast group is significantly higher than that of national standard,which showed the potential of the non-Saccharomyces yeasts for steamed bread production.