Fermentation by Multiple Bacterial Strains Improves the Production of Bioactive Compounds and Antioxidant Activity of Goji Juice

Microorganisms can be used for enhancing flavors or metabolizing functional compounds. The fermented-food-derived bacterial strains comprisingBacillus velezensis,Bacillus licheniformis, andLactobacillus reuterimixed withLactobacillus rhamnosusandLactobacillus plantarumwere used to ferment goji berry (Lycium barbarumL.) juice in this study. The fermentation abilities and antioxidant capacities of different mixtures of multiple strains in goji juice were compared. The results showed that the lactic acid contents increased 9.24–16.69 times from 25.30 ± 0.71 mg/100 mL in goji juice fermented using the SLV (Lactobacillus rhamnosus,Lactobacillus reuteri, andBacillus velezensis), SZP (Lactobacillus rhamnosus,Lactobacillus plantarum, andBacillus licheniformis), and SZVP (Lactobacillus rhamnosus,Lactobacillus plantarum,Bacillus velezensis, andBacillus licheniformis) mixtures, and the protein contents increased 1.31–2.11 times from 39.23 ± 0.67 mg/100 mL. In addition, their contents of volatile compounds increased with positive effects on aroma in the fermented juices. Conversion of the free and bound forms of phenolic acids and flavonoids in juice was influenced by fermentation, and the antioxidant capacity improved significantly. Fermentation enhanced the contents of lactic acid, proteins, volatile compounds, and phenols. The antioxidant capacity was strongly correlated with the phenolic composition.Keywords:goji juice;fermentation;multiple bacterial strains;volatile compound;antioxidant capacity