Enhancing the functional value of Andean food plants: Enzymatic production of γ-aminobutyric acid from tarwi, cañihua and quinoa real seeds’ proteins

Abstract

Gamma-aminobutyric acid (GABA) is known for its multiple physiological functions, including beneficial effects against several metabolic disorders. This study explores enzymatic strategies to enhance the functional value of Andean seeds, specifically tarwi ( Lupinus mutabilis ), cañihua ( Chenopodium pallidicaule ) and quinoa ( Chenopodium quinoa ) real varieties, by converting their naturally occurring glutamic acid into GABA. Two isoforms of glutamate decarboxylases (GADs) from Levilactobacillus brevis , GadA and GadB, separately produced in Escherichia coli , were used to convert the seeds’ glutamic acid into GABA. The activity of GAD enzymes was analysed with and without a prior pancreatin treatment to release free glutamic acid from the seeds' proteins. The results show that tarwi produced the highest levels of GABA, while the yields in cañihua and quinoa increased when treated with both pancreatin and GAD enzymes. An unexpected proteolytic activity from the GAD enzymes was observed, possibly contributing to further glutamic acid release and enhancing GABA production. This study denotes the initial exploratory enzymatic conversion of glutamic acid to GABA in Andean seeds, providing a novel approach to improve the functional value of these seeds in food and nutraceutical applications. These results also highlight the potential to optimize enzymatic methods to maximize GABA production in plant-based foods. • GadA and GadB from L. brevis successfully produced γ-aminobutyric acid (GABA) in Andean seeds. • Protein content in the seeds highly correlates with the amount of GABA produced. • A prior treatment with pancreatin released free L-glutamic acid to produce more GABA. • Interestingly, L. brevis GadA and GadB could also release L-glutamic acid and partially degrade β-casein.