Characterization of the effect of Levilactobacillus brevis CGMCC 1.5954 combined with Lactiplantibacillus plantarum subsp. plantarum CGMCC 1.5953 on the red bean sprouts GABA-enriched fermented milks.

Gamma-aminobutyric acid (GABA) is a neuroprotective neurotransmitter. This study investigates the effect of Levilactobacillus brevis CGMCC 1.5954 combined with Lactiplantibacillus plantarum subsp. plantarum CGMCC 1.5953 on the red bean sprouts GABA-enriched fermented milks. The results demonstrated that fermented milk from the complex fermentation has a GABA content of 241.3 μg/mL and 70.7% DPPH scavenging activity. Texture improved with 32% lower hardness and 14% higher water-holding capacity, supported by a denser protein network (G' = 470 Pa). Additionally, E-nose, HS-SPME-GC-MS and GC-IMS results showed that flavor profiles shifted from milky to fruity-ester, with elevated 1-hexanol, linalool, and 1-nonanol, alongside reduced sulfide response and astringency. Metabolic topology analysis revealed that fermentation enhanced the utilization of glutamate, aspartate, alanine, and glutamine through vitamin B6 metabolism, amino acid interconversion, and the γ-glutamyl cycle, thereby promoting the production of stress-protective metabolites (e.g., GABA). This finding is crucial for the development of GABA-enriched fermented milks.