Microbiota succession and metabolite changes during the traditional sourdough fermentation of Chinese steamed bread

This study was conducted to evaluate the changes in microbial communities and metabolites during the Chinese traditional sourdough fermentation. A gradual decrease in pH values was observed throughout the fermentation process. A considerable increase in LAB and yeasts counts was noticed during the primary stage of fermentation with the corresponding increase in amino acids, glucose, lactic acid and acetic acid. During the secondary fermentation stage, LAB count started decreasing slowly, while yeast count still increased, and reached to the maximum value. However, glucose, amino acid, lactic acid and acetic acid contents decreased slightly. PCR-DGGE results identified nine bacteria, six yeasts and one mold species during the whole fermentation process. Saccharomyces cerevisiae and Lactobacillus sanfranciscensis were the predominant species. These results would help to understand the LAB and yeasts influence on the metabolic process during the fermentation of steamed bread by Chinese traditional sourdoughs.