Optimization of fermented Perilla frutescens seeds for enhancement of gamma-aminobutyric acid and bioactive compounds by Lactobacillus casei TISTR 1500

Abstract Select LAB, including Lactobacillus fermentum TISTR 950, Lactobacillus plantarum TISTR 2265 and Lactobacillus casei TISTR 1500 were investigated for their ability to enhance GABA, TPC and the antioxidant activity of perilla seed juice. L. casei TISTR 1500 produced higher GABA and TPC contents and presented higher antioxidant activity than other strains. Furthermore, the optimal fermentation condition to perilla seeds inoculated with L. casei TISTR 1500 to improve the GABA, TPC and antioxidant activity was performed using 33 full factorial design. The final optimal values for perilla fermentation was found at fermentation time of 4.82 days (4 days 19 h 40 min), initial substrate of 5% (w/v) and fermentation temperature of 30.07 °C. Under the optimal fermentation condition, an observed values of GABA, TPC, ABTS, DPPH and FRAP were 71.46 µg/g, 3175.00 µg GAE/g, 1991.40 µg TEAC/g, 9178.29 µg TEAC/g and 7753.34 µg TEAC/g, respectively, which was 3.3, 0.9, 2.9, 10.8 and 10.2 times higher than that of unfermented perilla seeds, and 2.1, 0.8, 0.9, 10 and 9.2 times of fermented perilla seeds before the optimization. These results may provide the foundation to further target in industrial application for the production of plant-based and develop functional perilla seed products containing GABA. Highlights Improved GABA, TPC and antioxidant contents were found using Lactobacillus casei TISTR 1500 Full factorial design applied to optimize fermented perilla seeds by lactic acid fermentation The optimized conditions dramatically increased GABA and TPC contents