Effects of Fractions From a Multi‐Stage Rice Fermentation System on the Shelf‐Life and Flavor Quality of Chinese Steamed Bread

In the traditional multi‐stage glutinous rice wine fermentation, the key mash and liquid fermentation (MLF) system was separated into a cell‐free supernatant fraction (SF) and a cell‐rich microbial fraction (MF). This study investigated the effects of these two distinct fermentation fractions on the texture, shelf‐life, flavor, and sensory quality attributes of Chinese steamed bread (CSB) during storage. The results showed that dough supplemented with SF (SF‐dough) exhibited superior gas‐retention capacity, resulting in SF‐CSB with greater crumb structure. During storage at 4°C, the hardness of SF‐CSB increased at a significantly slower rate than that of yeast‐CSB (Y‐CSB), indicating that SF‐CSB has a better anti‐staling effect than Y‐CSB. SF significantly inhibited microbial growth and extended the shelf‐life of CSB. Notably, SF demonstrated antibacterial activity, effectively suppressing both Gram‐positive and Gram‐negative bacteria. In contrast, MF may contain heat‐resistant spore‐forming bacteria that negatively affected CSB shelf‐life. SPME‐GC‐MS analysis confirmed that SF addition enriched and preserved the volatile flavor profile in Y‐CSB, increasing the number of compounds (from 38 to 51) and the total concentration of volatile flavor compounds (from 187.95 ± 23.69 to 232.94 ± 29.32 µg/kg, p < 0.05), which was maintained at 204.30 ± 30.35 µg/kg after 7‐day storage. Notably, certain alcohol (1‐octen‐3‐ol), aldehyde (nonanal), and ketone (2,3‐butanedione) were identified as key aroma compounds distinguishing SF‐CSB from Y‐CSB.