Antioxidant activity and viability of Lacticaseibacillus rhamnosus, Lacticaseibacillus casei, and Co-culture in fermented tomato juice during refrigerated storage

Abstract

The fiber content of tomato juice (TJ) may serve as a suitable matrix for protecting probiotics bacteria (PB). The objectives of this study were to: (1) investigate the viability of PB in TJ, namely, Lacticaseibacillus rhamnosus (LG), Lacticaseibacillus casei (LC), and co-culture (LCG) during storage conditions and passing through the gastrointestinal tract and (2) determine the antioxidant activity and physicochemical stability of probiotic tomato juice (TJP) for 20-day refrigerated storage. TJ was separately fermented with single culture LG or LC or co-culture LCG at 37 °C for 72 h. Scanning electron micrographs showed PB immobilized with fibers in TJ, which indicated that PB was protected in TJ. When TJP was exposed to simulated gastric and intestinal fluids, viability was greater than 7 log CFU/mL regardless of the strains after 120 min. Counts for LG, LC, and LCG were 8.7, 8.7, and 9.0 log CFU/mL, respectively, after 20-day storage. TJ without probiotics had the least lycopene content after 20-day storage. The antioxidant capacity of TJP was not significantly different (p < 0.05) after 20-day storage. This study demonstrated that probiotics in the TJP could survive, and TJP maintained the antioxidant activity during the storage.