Analysis of Differences in Metabolite Composition and Bioactivity of Black Mulberry Fruits from Four Production Regions in Xinjiang

To elucidate the impacts of climatic and edaphic factors on the chemical composition and bioactivities of black mulberries, this study conducted a systematic comparative analysis of fruits sourced from four regions in Xinjiang: Turpan (T), Bayingolin Mongol Autonomous Prefecture (B), Hotan (H), and Kashgar (K). H exhibited the highest contents of total phenolics and total tannins, whereas T showed elevated levels of total flavonoids and flavan-3-ols. Notably, samples from B and H demonstrated superior antioxidant potential. Using UPLC-MS/MS, a total of 48 anthocyanin metabolites and 4 non-anthocyanin metabolites were identified in the mulberry fruits. Among these, 6 were region-specific compounds, and 8 were identified as differential metabolites. Furthermore, headspace solid-phase microextraction (HS-SPME) coupled with GC-MS/MS revealed 292 volatile metabolites, of which 15 were identified as differential metabolites based on OPLS-DA and relative odor activity value (rOAV) analyses. Metabolite profiling indicated that B possessed the greatest diversity of volatile metabolites, while T exhibited a remarkable richness in anthocyanin diversity. The observed regional variations in chemical constituents and metabolite profiles collectively accounted for the differences in antioxidant capacity and enzyme inhibitory activities among the black mulberry fruits. These findings provide a theoretical foundation for the regional characterization and targeted processing of black mulberries from the four production areas in Xinjiang.