Rice GABA®: Valorization of rice germ through lactic acid bacterial precision fermentation for enhanced GABA production and functional properties

Globally, rice production generates approximately 10-million metric tons of rice germ annually, representing 2–3% of the 758 million tons of paddy rice produced. Despite its nutrient density, rice germ is discarded due to challenges such as rapid lipid oxidation-linked spoilage. This study addresses this underutilization by developing an innovative lactic acid bacterial precision fermentation process to transform agro-waste into Rice GABA ® (RG), a GABA-enriched rice germ fermented extract as a functional ingredient with neuroprotective properties. Using Lactobacillus brevis BJ20 to ferment enzymatically hydrolyzed rice germ supplemented with monosodium glutamate (MSG), optimal conditions of 8% MSG addition and 72 h fermentation achieved an 80% GABA conversion efficiency, with GABA constituting 87.9% of total free amino acids. Physicochemical analysis of RG revealed nanoscale bioavailability features, including an average particle size of 290.17±11.85 nm and a molecular weight distribution showing that 75% of molecules were below 300 Daltons. RG demonstrated significant neuroprotective effects in corticosterone-induced stressed human neuroblastoma, improving cell viability by 35% and reducing lactate dehydrogenase release by 58%. This study highlights the feasibility of valorizing rice germ into a high-value functional ingredient through sustainable bioprocessing, addressing both circular economy principles and consumer demand for health-promoting products. The unique nutritional and neuroprotective efficacy of RG positions it as a promising candidate for neurological health applications.