Evaluating the Gamma-Aminobutyric Acid Producing Capacity of Lactic Acid Bacteria and Their Application in a Coconut Matrix

Gamma-aminobutyric acid (GABA) is a non-protein amino acid that provides numerous health benefits. GABA is produced from Glutamic acid (Glu) by Glutamate decarboxylase, an enzyme excreted by certain microorganisms. This study focused on the bioconversion of Glu in mature-coconut-water and young-coconut-kernel to develop GABA enriched food. First, seven strains of lactic acid bacteria (LAB) were screened for their GABA-producing capacity on de Man-Rogosa-Sharpe medium supplemented with Glu. Both thin layer chromatography and spectrophotometric results confirmed the ability of LAB to convert Glu to GABA. Lactobacillus plantarum-H was selected for application on the coconut substrate. The growth of colonies and the decrease in pH demonstrated the survival of L. plantarum-H on this food matrix. The fermentation of the mixture of mature coconut water:young coconut kernel (2:1, v/w) resulted in a GABA yield of 926.18 ± 25.71 mg/L. These findings highlight the potential to enhance the value of the coconut substrates and to develop GABA-enriched fermented foods, such as coconut yogurt, using GABA-producing LAB.