Rosa roxburghii Tratt belongs to the Rosaceae family, which is mainly distributed in southwest regions of China, including Guizhou, Xiangxi, Sichuan, and Yunnan. Its fruits are well-known for nutritional value and health benefits because they contain a diverse group of bioactive compounds such as vitamin C, phenolic compounds, polysaccharides, and SOD (Li et al., 2023). Ripe rosa roxburghii Tratt fruits (RRT) have a yellow spiky exterior covered in bristles, with acid and astringent taste. Therefore, they are rarely consumed directly, but are processed into juice, beverages and candies.

Fermentation is a traditional food processing, which can considerably transform the nutritional profile and flavor of foods. Lactic acid bacteria (LAB) are of great importance to certain fermented products such as pickles and yogurts. Fruits are considered suitable substrates for LAB fermentation, which can provide new tasty products to consumers (Muhialdin et al., 2021; Ruiz Rodríguez et al., 2021a, Ruiz Rodríguez et al., 2021b). Several studies have shown that LAB fermentation is a feasible approach to improve the sensory properties and biological activities of fruit juice. Zheng et al. (2023) reported that mixed-culture fermentation with Lactococcus lactis subsp. lactis YM313 and Lacticaseibacillus paracasei ZH8 resulted in a positive shift in the composition of juice including acid, sugar and amino acid, which are crucial to the flavor of wolfberry-longan juice. In addition, the fermentation significantly enhanced the antioxidant capacity of wolfberry-longan juice. Similarly, Liu et al., 2023a, Liu et al., 2023b found that the volatile and nutritional profiles of mango juice was enhanced by LAB fermentation. Li et al. (2023) verified that Lactobacillus acidophilus GIM1.208 could reduce the bitterness and astringency of RRT juice, and improve its aroma. Moreover, this strain was capable of hydrolyze glycosidic bond and therefore contributed to an increase in the formation of active aglycones and better antioxidant activity.

Currently, there are a few studies focused on the effects of LAB fermentation on the physicochemical characteristics, flavor compounds, glycosides and bioactivities of RRT juice (Zhou et al., 2023; Li et al., 2023). However, no study reporting on comparisons of the impacts of different lactobacilli on the components and functions of RRT juice were found. In this study, we aimed to investigate the comprehensive effects of pure fermentation with single LAB strains of Lactobacillus plantarum FBKL1.0310 and Lactobacillus paracasei FBKL1.0328 on the non-volatile constituents, free radical scavenging abilities, α-glucosidase and cholesterol esterase inhibitory activities of RRT juice. Widely targeted metabolomics was employed to reveal the effects of different LAB fermentation on the non-volatile composition of RRT juice. The results of this study will provide a sound reference for RRT or other fruits fermentation processing.