Metabolic Remodeling and Flavor Enhancement of Mulberry Juice Through Lactic Acid Bacteria Fermentation: A GC-IMS and Untargeted Metabolomics Approach

Fresh mulberry juice (MJ) faces industrial challenges due to its short shelf life and inconsistent flavor. This study innovatively addressed these limitations by applying <i>L. plantarum</i> (LP) and <i>L. fermentum</i> (LF) fermentation to MJ, combining non-targeted metabolomics and GC-IMS to systematically elucidate metabolic remodeling and flavor enhancement. Fermentation (36 h) achieved LAB counts > 7 log CFU/mL, significantly reducing soluble solids and pH from 15.00 to 13.90, 14.01 °Brix and 3.74 to 3.21, 3.13, respectively. In contrast, the bioactive compounds as detected by the increase in flavonoids and phenolics from 254.85 mg/100 g to 289.36, 291.39 mg/100 g and 286.21 mg/100 g to 294.55, 302.2033 mg/100 g, respectively. Anthocyanin content as high as 165.88 and 156.69 mg/L. Metabolomics identified enriched amino acid pathways, and GC-IMS revealed unique flavor profiles. The study fills a research gap by demonstrating LAB fermentation's dual role in extending MJ's shelf life and improving its functional nutritional quality, offering a novel strategy for functional food development.