Production and Evaluation of a Novel GABA-Producing Plant Yogurt and its Functional Benefits

Depression and anxiety are prevalent mental health disorders, and growing evidence implicates the gut–brain axis in the regulation of neurophysiological processes. Psychobiotics, defined as probiotics with potential effects on the gut–brain axis, have consequently gained attention as candidate functional food components. However, the application of human breast milk-derived psychobiotic strains in the development of GABA-enriched fermented foods remains largely unexplored. Gamma-aminobutyric acid (GABA), the principal inhibitory neurotransmitter in the mammalian central nervous system, is a bioactive metabolite produced by certain microorganisms during fermentation. In this study, the previously characterized GABA-producing strain Enterococcus faecalis RIT BM_S15-3, isolated from human breast milk, was employed as a starter culture for the development of GABA-enriched almond yogurt. Fermentation conditions were systematically optimized by evaluating L-monosodium glutamate (L-MSG) concentration, fermentation temperature, and fermentation time to maximize microbial GABA production. The optimized formulation was subsequently characterized for GABA stability, antioxidant activity, water-holding capacity, viscosity, and sensory properties. Fermentation with E. faecalis RIT BM_S15-3 enhanced GABA production in the almond-based matrix, and the optimized yogurt retained detectable GABA levels and viable bacterial counts during storage. The fermented product also demonstrated measurable antioxidant activity and acceptable sensory characteristics. Overall, the findings demonstrate the feasibility of utilizing a human breast milk-derived GABA-producing bacterial strain for the development of a plant-based fermented food with enhanced bioactive value. Further in vivo and clinical investigations are warranted to determine whether consumption of the GABA-enriched product translates into measurable neurophysiological or mental health benefits.