Title : Kefir fermentation enhances GABA content and antioxidant capacity in plant-based flours
Abstract:
Gamma-aminobutyric acid (GABA), a non-protein amino acid with recognized bioactive properties, can be produced by fermentation of various food matrices, with kefir emerging as a promising source of this compound. This study aimed to evaluate kefir-fermented flours derived from soybean, Carioca bean, and peanut ‒ raw materials of major economic importance and widely cultivated in Brazil ‒ to enhance GABA production. The flours were fermented using a pre-activated commercial kefir culture (8.48 log10 CFU/mL) supplemented with 1.2% (w/v) glutamic acid for 24 and 48 h at 25°C. GABA was identified and quantified by HPLC-DAD, and pH was monitored at each fermentation interval. Both non-fermented and fermented samples were also evaluated for antioxidant capacity by ORAC assay and for total phenolic content using the Folin-Ciocalteu method. The results showed that 24 h of fermentation yielded the highest GABA levels, particularly in Carioca bean flour, which reached 113 µg/mL ‒ approximately twice the concentration observed in fermented soybean and peanut flours. After 48 h, GABA concentrations decreased in all samples. Fermentation increased the total phenolic content in all flours compared to non-fermented controls, with soybean flour fermented for 24 h exhibiting the highest value (157 µg GAE/mL). Carioca bean and soybean flours also showed the highest antioxidant capacity after 24 h of fermentation (9,921 and 8,563 µmol TE/mL, respectively). These findings demonstrate the potential for developing a novel functional ingredient enriched with GABA and bioactive compounds, supporting its application in the formulation of value-added foods.
This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance code 001.
