Optimizing ultrasonic-assisted extraction of peach gum polysaccharide: Balancing yield and bioactivity through...

Ultrasound-assisted extraction (UAE) is efficient for plant polysaccharides but faces a "high yield and low bioactivity" contradiction in peach gum polysaccharides (PGPS) extraction. To address this, this study used dual response surface methodology (RSM) to optimize PGPS's UAE process, targeting two conflicting responses: extraction yield (Y₁) and α-glucosidase inhibitory rate (Y₂). The optimization adopted a Box-Behnken design (BBD) with three independent variables: ultrasonication power (X₁), temperature (X₂), liquid-solid ratio (X₃), which were selected via systematic single-factor experiments. RSM results showed Y₁ was significantly affected by X₁, X₂, X₁², X₂², X₃², and Y₂ by X₃, X₁X₃, X₃² (P < 0.05). Four optimized UAE conditions were obtained via desirability function; their PGPS products' structural features were characterized and differentiated by principal component analysis (PCA). Results showed yield was negatively associated with galactose, and α-glucosidase inhibitory activity positively with arabinose. Finally, optimal conditions were 20 min UAE at 176 W, 74 °C, and 240 mL/g liquid-solid ratio. Under these conditions, PGPS achieved 81.19 % yield and 40.72 % inhibitory rate. NMR analysis indicated "high yield - high activity" PGPS consisted of a → 6)-β-D-Galp-(1 → backbone, with short →3)-α-L-Araf-(1→, →5)-α-L-Araf-(1 → or →3)-β-D-Galp-(1 → side chains at galactose O-3, terminating in β-D-Xylp and occasionally α-L-Araf.