Freeze–microwave vacuum drying optimizes structure and dual antidiabetic activities of Pyracantha fortuneana fruit polysaccharides

Drying regimes strongly shape fruit-polysaccharide structure and antidiabetic function, yet their structure-function consequences in Pyracantha fortuneana remain unclear. Six scalable methods-natural (ND), hot-air (HD), infrared (IRD), freeze-drying (FD), microwave-vacuum (MVD), and freeze-microwave-vacuum drying (FMVD)-were therefore compared for their effects on P. fortuneana fruit polysaccharides (PFPs). FMVD produced the highest polysaccharide yield (6.22 %) and uronic acid content (45.48 %), while lowering weight-average molecular weight from 740.47 to 134.08 kDa relative to ND and generating low-crystallinity, thermally stable polymers. These structural advantages translated into superior bioactivity: PFP-FMVD showed the strongest α-glucosidase inhibition with an IC₅₀ of 0.51 mg/mL. In a BSA-glucose model, PFP-FMVD most effectively attenuated the Maillard cascade, inhibiting early fructosamine formation by 62.27 % at 8 mg/mL and reducing fluorescent advanced glycation end products (AGEs) with an IC₅₀ of 3.48 mg/mL. Multivariate correlation, kinetic, and spectroscopic analyses established a quantitative structure-activity rule: higher galacturonic/uronic acid content and lower molecular weight, together with stronger static, mixed-type binding to α-glucosidase and helix-to-sheet transitions in the enzyme, underpin enhanced dual antihyperglycemic and antiglycation activities. FMVD is thus identified as the most effective drying strategy for engineering PFPs with optimized functional performance, providing mechanistic guidance for designing polysaccharide-based functional ingredients for diabetes management.