Gamma-Aminobutyric Acid (GABA): Natural Sources, Enrichment Technologies, Physiological Functions, and Food...

GABA is a neurotransmitter and a four-carbon non-protein amino acid that is produced from L-glutamate through an enzymatic decarboxylation reaction catalyzed by glutamate decarboxylase (GAD). This amino acid is naturally present in microorganisms, plants, and animals. As a neurotransmitter in the central nervous system of mammals, GABA plays a pivotal role in regulating neuronal excitability and maintaining the balance of neural activity. Growing interest in improving human health and developing functional foods has increased global attention toward GABA, leading to considerable interest in its incorporation and enrichment in food products. Despite the potential health benefits of GABA, endogenous GABA concentrations in many food matrices are relatively low, limiting their potential as dietary sources. Consequently, enrichment strategies, including fermentation, germination, and other bioprocessing approaches, have attracted attention as alternatives to direct GABA addition and may facilitate the development of GABA-enriched functional foods. Overall, this review provides a comprehensive framework for understanding GABA biosynthesis, its physiological functions, and its applications in food products. It also discusses current strategies for GABA enrichment and highlights the factors influencing its production and applications.