Vacuum Concentration Induces Phytochemical Remodeling and Quality Transitions in a Multi-Botanical Yam-Wolfberry Beverage

Vacuum concentration is widely used to reduce water content in plant-based beverages, yet it can simultaneously enrich soluble constituents and promote selective chemical alteration. How these competing processes reshape the molecular composition and quality of complex multi-herb beverages remains poorly understood. Here, we integrated time-resolved physicochemical, taste, antioxidant and untargeted metabolomic analyses to investigate the concentration of a yam-wolfberry beverage formulated from seven food-medicine botanicals. During vacuum concentration at 60 °C, quality attributes changed non-linearly over 0–240 min, with a marked transition occurring around 180 min. Total phenolic content and DPPH radical-scavenging activity reached their highest levels at this stage, whereas prolonged processing reduced soluble protein content and umami intensity; ABTS radical-scavenging activity increased throughout concentration. Untargeted UHPLC–MS/MS analysis identified 190 differentially accumulated metabolites between the unconcentrated and 180 min samples. Relative to the theoretical 1.84-fold concentration factor, 90 metabolites showed increases exceeding passive physical enrichment, 11 were consistent with concentration-driven enrichment, and 89 decreased despite water removal. Over-representation analysis of the increased metabolites highlighted aminoacyl-tRNA biosynthesis, cyanoamino acid metabolism, D-amino acid metabolism, and phenylalanine, tyrosine and tryptophan biosynthesis. These findings indicate that vacuum concentration induces stage-dependent quality changes through the combined effects of physical enrichment and selective metabolite remodeling, offering mechanistic insights for quality-oriented processing of complex botanical beverages.