Effects of Lactobacillus acidophilus GIM1.208 on antioxidant and hypoglycemic activities, flavor and glycosides of Rosa roxburghii Tratt

Lactobacillus acidophilus GIM1.208 (LA) can greatly improve the volatile flavor and sensory scores of Rosa roxburghii Tratt (RRT), while its effects on nonvolatile flavor and active compounds remains uncertain. Therefore, this study used widely targeted metabolomics to comprehensively analyze the effects of LA on flavor and activity of RRT. After being fermented by LA, the total phenolics and flavonoids content of RRT increased, while the total triterpenoids content slightly decreased. The total antioxidant activity rose by 35.23%, and hypoglycemic activity expressed through α-amylase and α-glucosidase inhibitory activities increased by 51.66% and 24.95%, respectively. A total of 1635 metabolites were identified, including amino acids, phenolic acids, flavonoids, and triterpenes, and 205 different metabolites were screened. The analysis of potential taste-related metabolites among differential metabolites revealed a reduction in amino acid content, while the majority of organic acids and sugars exhibited an increase. The electronic-tongue and electronic-nose showed that LA reduces bitterness and astringency while enhancing the aroma of RRT, indicating changes in flavor compounds lead to improved flavor quality. Additionally, LA can hydrolyze glycoside compounds in RRT and release glycosides with higher activity, which contributes to its increased antioxidant and hypoglycemic effects. In summary, LA induced alterations in the flavor compounds and glycosides of RRT, thereby improved its flavor and activity. This study can serve as a reference for future research on the flavor and activity of RRT, as well as for production quality control.