Fermentation with Lactobacillus reuteri and Lachancea fermentati improves the bioactivity and flavor-sensory characteristics of Rosa roxburghii Tratt. juice.

The application of Rosa roxburghii Tratt. (RRT) is restricted by its astringency despite its rich nutrient content. This study employed mixed fermentation of RRT juice using Lachancea fermentati and Lactobacillus reuteri. The results showed that the total acidity of the mixed fermentation group (RF) peaked at 20.00 g/L within 12 h, significantly exceeding that of the single-strain fermentation groups. RF enhanced antioxidant activity and exhibited potent in vitro xanthine oxidase (XOD) inhibitory activity, achieving an inhibition rate of 81.72%. Furthermore, RF improved the flavor profile by increasing ester diversity to 14 types while reducing isoamyl alcohol-related off-flavors. Metabolomics and electronic tongue analyses confirmed enhanced umami and richness, driven by the upregulation of flavonoids and umami amino acids. Consequently, co-fermentation showed superior overall performance under the tested conditions in improving flavor and functionality, thereby facilitating the development of high-quality functional beverages.