Production of γ-aminobutyric acid in black raspberry juice during fermentation by Lactobacillus brevis GABA100

Black raspberry juice was fermented to produce γ-aminobutyric acid (GABA) using lactic acid bacteria (Lactobacillus brevis GABA 100) at different temperatures (25, 30, or 37 °C) and pHs (3.5, 4, 4.5, 5, 5.5, or 6) for 15 days. Concentrations of GABA in the juices were determined during fermentation using HPLC. GABA was produced continuously even if the viable bacterial counts markedly decreased. The fermentation at 30 °C generally showed higher production of GABA in the juices than those at 25 and 37 °C. The GABA in the juices fermented at 30 °C reached the maximum levels on the 12th day. The juices fermented at lower pH and lower temperature showed a lower degradation of monomeric anthocyanins. The results suggest that black raspberry juice can be GABA enriched using lactic acid bacteria.