Production of plant-based fermented beverages possessing functional ingredients antioxidant, γ-aminobutyric acid and antimicrobials using a probiotic Lactiplantibacillus plantarum strain L42g as an efficient starter culture.

Plant-based probiotic beverages have gained increasing interest due to demand from health-conscious consumers. In this study, we aimed to isolate and screen lactic acid bacteria possessing functional properties for use as a starter culture of fermented almond and coix beverages. Lactiplantibacillus plantarum L42g isolated from fermented beef was selected. Both intact cells and cell free supernatant of this strain exhibited high antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging at 38.2% and 44.9%, respectively. L. plantarum L42g grown in MRS broth supplemented with 1% (w v) monosodium glutamate (MSG) produced a large amount of γ-aminobutyric acid (GABA) at 496.7 μg mL. Moreover, strain L42g displayed remarkable antibacterial activity against several potential foodborne bacterial pathogens, including Bacillus cereus, Listeria monocytogenes, Listeria inocua, Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, Salmonella enterica subsp. enterica serovar Typhimurium, Shigella sp., Vibrio cholerae and Vibrio parahaemolyticus. Strain L42g also possessed additional probiotic properties including abilities to tolerate gastrointestinal conditions, adhere to gut mucosa, co-aggregate with pathogens, be susceptible to antibiotics, and produce protease. Probiotic strain L42g was subsequently employed in fermenting almond and coix juices containing MSG (1%) supplementation. Levels of antioxidant, GABA and antibacterial formation along with cell growth were clearly higher in fermented almond juice than in fermented coix juice. Nonetheless, both fermented almond and coix juices meet the standards required for the consumption of fermented beverages. Therefore, L. plantarum strain L42g represents a promising starter culture for producing functional plant-based probiotic beverages.