Effects of Fractions From a Multi-Stage Rice Fermentation System on the Shelf-Life and Flavor Quality of Chinese...

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.