Characterization of scalded dough and its impact on the growth of mixed yeasts originating from Jiaozi

The use of scalded dough fermentation has become increasingly popular because of its positive effects on product texture, safe quality and flavor. In this study, the characteristics of scalded wheat dough and its influence on the evolution of mixed yeasts, namely Saccharomyces cerevisiae Y10, Wickerhamomyces anomalus Y13 and Torulaspora delbrueckii Y22 were investigated. Scalding water temperature above 90 °C significantly reduced the number of microorganisms. Bacillus spp. and some filamentous fungi survived the scalding process. Starch partially gelatinized during scalding, which resulted in the porous microstructure and increased reducing sugar content of dough. In the scalded dough with flour/boiling water ratio less than or equal to 1/1, the cell number of S. cerevisiae Y10 decreased from 6.5 log CFU/g dough to approximately 5.6 log CFU/g dough after 12 h of dough fermentation, but the W. anomalus Y13 and T. delbrueckii Y22 cell populations increased significantly (p < 0.05). When the flour/boiling water ratio was greater than 1/1, Y10 was the dominant yeast, and the inoculation ratio of the three yeasts had no effect on its dominant position in the fermented scalded dough. The results revealed the importance of controlling the scalding parameters when mixed yeast cultures were used in scalded dough fermentation.