Novel insights into the metabolic characteristics and potential probiotic activity of fermented Malus prunifolia juice

To improve the flavour and probiotic properties of Malus prunifolia (MP), we prepared fermented MP juice with a mixture of plant-derived probiotics. Changes in the quality of the MP juice during fermentation were explored alongside the differences in its metabolites and potential probiotic components. Results showed that the flavour of MP juice was enhanced after fermentation, and the main flavour compounds of MP included aromatic components and alkanes. Thirty compounds, including phlorizin and benzaldehyde, were prominent in the MP juice. After fermentation, 44 differential metabolites were produced, including maltitol, isoniazamide and gentisin, showed significant increase in their levels. The potential probiotic components present in fermented MP juice included caffeic, hydroxycinnamic and sinapic acids. It is speculated that fermented sea-red fruit juice had obvious anti-oxidant and anti-viral properties and could prevent alcoholic fatty liver and neurological diseases. Glucose and carbohydrate metabolism were crucial pathways involved in fermentation. The results of this study provide a theoretical basis for the deep processing and industrial development of MP. • The quality changes of MP juice during fermentation were excavated. • 74 differential metabolites before and after fermentation were discovered. • Potential probiotics in fermented MP juice were found. • 4 important pathways during MP juice fermentation were excavated.