Impact of Leavening Agents on Flavor Profiles and Microbial Communities in Steamed Bread: A Comparative Analysis of Traditional Chinese Sourdough and Commercial Yeast

Chinese steamed bread (CSB) made with commercial yeasts and traditional Chinese sourdoughs was analyzed for the flavor and microbial communities. Sensory attributes were assessed using quantitative descriptive analysis (QDA). Results showed that commercial yeast CSB-1 (JMMT1), a yeast-based sample, had stronger milky and sweet attributes, while commercial yeast CSB-2 (JMMT2) had more pronounced yeasty attributes. Among the sourdough-based samples, Shandong traditional sourdough steamed bread (SDMT) exhibited a winelike character with a weak sweet aftertaste, whereas Shanxi traditional sourdough steamed bread (SXMT) had a distinct sour attribute and a less prominent floury taste. SAFE-GC-O-MS analysis identified 40 aroma compounds with FD values ≥2, including 33 key aroma compounds with an OAV of ≥1. Compounds such as 2,3-butanediol, decanal, methyl isobutenyl ketone, gamma-nonanolactone, ethyl caprate, 2-ethylhexyl acetate, vanillin, and indole contributed significantly to the diverse aroma profiles. High-throughput sequencing revealed dominant strains: Bacillus in JMMT1, Lactobacillus in JMMT2, Bacillus in SDMT, and Lactobacillus in SXMT. Over two-thirds of the aroma compounds showed correlations with microorganisms. Notably, Acetobacter exhibited a highly significant correlation with butanoic acid, while Lactobacillus played a significant role in the formation of ester flavors. These findings contribute to the flavor evaluation and microbial community analysis of steamed bread made with different leavening agents, providing valuable insights into their relationship.