Two lactic acid bacteria strains isolated from naturally fermented foods improves physicochemical quality, antioxidant capacity, shelf life stability and metabolic profiles of Dangshan pear (Pyrus spp.) juice.

Lactic acid bacteria fermentation can enhance the biological activity and unique flavor of food through the conversion of nutrients. In this study, physicochemical and untargeted metabolomics analyses were performed on the fermented Dangshan pear juice (DSPJ) to determine the effects of Lactiplantibacillus plantarum MPS-PJ241 and Lacticaseibacillus paracasei TD-PJ242. Both single and mixed strains could adapt to the pear juice matrix with colony counts more than 12 log CFU/mL and convert the sugar into organic acid with a decrease in the pH from 5.37 ± 0.01 to 3.59 ± 0.01. Furthermore, lactic acid bacteria fermentation reduced the total weight and average particle size of stone cells, enhanced the antioxidant capacity and shelf life stability, and changed the metabolic profiles of the fermented DSPJ. Additionally, metabolic pathways of 343 differential metabolites in fermented DSPJ were predominantly enriched in metabolism and amino acid biosynthesis pathway. Interestingly, D-phenyllactic acid, N-lactoyl-phenylalanine and indole-3-lactic acid were derived from metabolic pathways affecting the shelf life stability and functional properties of DSPJ. These findings provide important theoretical support for future studies to establish probiotics-juice quality-function interactive relationship.