Microbial diversity in traditional type I sourdough and jiaozi and its influence on volatiles in Chinese steamed bread

摘要

The aim of this work was to investigate the microbial diversity of jiaozi (n = 7) and type I sourdoughs (n = 8) by culture-dependent and culture-independent analysis and explore the effect of these starter cultures on the generation of volatiles in steamed breads. Both starter cultures significantly varied in terms of their pH, TTA and moisture content (P & 0.001); however, no significant difference in cell density of presumptive lactic acid bacteria (LAB) and yeast (P & 0.05) was found. The culture-dependent and culture-independent approaches revealed that Weissell.a cibaria and Lactobacillus sanfranciscensis were predominant in the microbiota of jiaozi and type I sourdoughs, respectively. Saccharomyces cerevisiae and Candida luimilis were the most common yeast species in all samples. A total of 36 volatile compounds were detected in all steamed breads. The products fermented with jiaozi had a relative high concentration of volatiles synthesized by amino acid metabolism. However, products fermented with type I sourdough were dominated by acids, furans, aldehydes and their corresponding alcohols. The principal component analysis distinguished the two starter cultures, based on the abundance of bacterial species as well as the total volatile composition of their respective steamed breads. We conclude that the production of volatile compounds strongly correlated with the microbiota involved in fermentation.