New plant-based kefir fermented beverages as potential source of GABA

The aim of this study was to assess the gamma-aminobutyric acid (GABA) production in plant-based fermented beverages with kefir cultures (milk and water kefir). Water-soluble extracts of peanut and Brazil nut were evaluated as non-dairy substrates for the development of new bioactive beverages. A total of 12 formulations were developed and evaluated for their chemical composition, physical chemical characterization, and microbiological counts (aerobic mesophilic bacteria, lactobacilli, lactococci and yeasts). Results proved that the composition of kefir culture, the nature of the extract and the addition of glutamic acid affected GABA production. Even peanut extracts presenting higher protein content, Brazil nut extracts was the best substrate for GABA production. In addition, fermented beverages were evaluated for in vitro antihypertensive activity through angiotensin-converting enzyme (ACE) inhibition. The formulations with GABA presented the most efficient ACE-inhibition, wherein beverages based on Brazil nut extract showed the highest results of ACE-inhibition (80%). This study evidenced that kefir fermentation enhanced plant-based beverages bioactivity, indicating their potential as functional beverages. The plant-based extracts and the bioactive compounds produced in this study characterize the beverages in an innovative way, due to the process, composition and simultaneous presence of probiotics and GABA, which had not been reported before.