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Tomato (Solanum lycopersicum L.) is a nutritious fruit and vegetable. Fermentation can be used to enhance their nutritional value. In this study, the tomato juice was co-fermented with multistrains, optimized by uniform experimental design and response surface methodology. Superoxide dismutase activity reached 496.67 U/g and lycopene content reached 77.12μg/g when P. pentosaceus (53.79%), L. casei (13.17%), L. plantarum (19.87%), L. fermentum (13.17%). To gain insight into the dynamics of metabolites during the tomato fermentation juice process multivariate statistical analysis was performed using the UHPLC-QE-MS/MS method. The main metabolites are peptides, amino acids carbohydrates, organic acids, and phospholipids. Carbohydrates were fully retained at the end of fermentation.The content of galactitol increased from the initial 5.389 to 6.607 while the content of cytarabine decreased by 29% and uridine by 44%. Meanwhile, phospholipids (PS, PE, PC, PG, PI) were all retained by more than 70%. Terpenoids (16-deacetylgairin, (+)-Royleanone, artemisinin) were increased to varying degrees, which gives them good nutritional value and biological activity. Organic acids (malic and citric) were reduced and lactic acid content was increased, changing its original flavor and making it more palatable to the general population. The research results have demonstrated the benefits of lactic acid bacteria fermentation on tomato juice, providing a theoretical basis and reference for the fermentation metabolism process of tomato juice.

Sea buckthorn (Hippophae rhamnoides L.) is an edible and medicinal plant species. However, due to its sour taste, it is not readily accepted by consumers. To overcome this, fermentation can be used to change its flavor profile. In this study, we used response surface methodology (RSM) to determine the best process for producing fermented sea buckthorn juice (FSBJ) using probiotics. The biological enzyme activity and total flavonoid content (TFC) of sea buckthorn juice (SBJ) increased after fermentation. When the number of bacteria inoculated was 4.08 × 106 CFU/mL and the inoculation ratio was 30% Z. mobilis, 5% L. casei, 13.75% L. plantarum, 31.25% P. acidilactici, 12.5% L. animalis, and 7.5% P. pentosaceus, the amount of sugar was 2.98% (w/v) after 20 h of fermentation at 37°C, and the superoxide dismutase (SOD) activity reached 725.44 U/mL, and the TFC reached 2.38 mg/mL. FSBJ demonstrated strong antimicrobial activity against Escherichia coli, Staphylococcus aureus and Botrytis cinerea. Then, to investigate the antioxidant capacity of FSBJ, we used H2O2 to induce oxidative stress in C2C12 cells and assessed the protection conferred by FSBJ to damaged cells. It was discovered that after 24 h of treatment with FSBJ, not only was there an increase in the activities of intracellular SOD and glutathione peroxidase (GSH-Px), but also a reduction in reactive oxygen species (ROS) content, catalase (CAT) activity, and malondialdehyde (MDA) content. This research lays the theoretical groundwork and provides reference materials for the improved fermentation of sea buckthorn and demonstrates its resulting antioxidant effect.

Quinoa seeds are a food resource rich in protein, vitamins, minerals, and other functional components such as polyphenols, polysaccharides, and saponins. The seeds have become favored by modern consumers due to being gluten-free and featuring a high protein content. This study focused on the preparation of quinoa peptides by short-time enzymatic-assisted fermentation. Quinoa flour (QF) was mixed with water in a certain ratio before being enzymatically digested with 0.5% amylase and 0.1% lipase for 6 h. Then, 16 bacterial taxa were used for fermentation, respectively. The peptide content in the resulting fermentation broths were determined by the biuret method. The dominant taxon was then identified and the peptide content, amino acid distribution, and molecular weight distribution of the prepared quinoa peptides were analyzed. Further, the temperature, pH, metal ions, organic solvents, ion concentration, and anti-enzyme stability of the quinoa anti-hypertensive peptides of different molecular weights after fermentation with the dominant taxon were investigated. Finally, the inhibitory activity of fermented quinoa peptides on bacteria was studied. The results show that the peptide content of the fermentation broth reached 58.72 ± 1.3% at 40 h of fermentation with Lactobacillus paracasei and the molecular weights of the hydrolyzed quinoa peptides were mainly distributed below 2 kDa by polyacrylamide gel. The Angiotensin Converting Enzyme (ACE) inhibition and peptide retention of the 0–3 kDa quinoa peptides were screened to be high and stable. At the same time, the inhibitory activity of quinoa peptide after fermentation on E. coli was obvious. This study provides a theoretical basis for further research on quinoa peptide and its application in industrial production, and also lays a foundation for the later application of polypeptides in new food and chemical products.