Innovative co-fermentation of Propionibacterium freudenreichii and Rhizopus oryzae enhances vitamin B12, riboflavin, and flavor profile components in sweet fermented glutinous rice

This study explores nutritional and sensory enhancement via co-fermentation of Propionibacterium freudenreichii (DSM 20271; J117) and Rhizopus oryzae (Angel Yeast Co., Ltd. starter) in sweet fermented glutinous rice (SFGR). After 72-h fermentation, the co-culture significantly increased vitamin B12 (15 ng/mL) and riboflavin (95 ng/mL) compared to Rhizopus-only controls (undetectable B12; 60 ng/mL riboflavin). HS-SPME-GC-MS analysis revealed increased ester diversity (3.0-7.4 % of total volatiles) in co-fermented samples versus the control (0.2 %), highlighting fruity esters such as ethyl propionate. Alcohol content remained below 1.5 % (v/v), aligning with non-alcoholic beverage trends. Antioxidant capacity (DPPH assay) remained high (30.7-31.7 %), comparable to traditional rice wines. Sensory evaluation indicated enhanced floral, fruity, and dairy-like notes in co-fermented samples, especially with strain J117. The synergy between starch hydrolysis by R. oryzae and vitamin biosynthesis by P. freudenreichii demonstrates an innovative strategy for fortifying traditional fermented foods while preserving sensory quality, offering considerable potential for new rice-based beverages.