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

초록

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 (R) (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 Da. 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.

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