Effect of ultrasound assisted H2O2 degradation on longan polysaccharide: degradation kinetics, physicochemical properties and prebiotic activity

This study aimed to investigate the effect of ultrasound-assisted H 2 O 2 (US/H 2 O 2 ) reaction on degradation parameters and kinetics, physicochemical properties and prebiotic activity of longan polysaccharide (LP). Results showed that US/H 2 O 2 had a synergistic effect on the degradation of LP, and its kinetic equation followed to the fist – order model. US/H 2 O 2 degradation did not change the chemical and monosaccharide composition of LP but altered their ratio. Compared with LP, three degraded polysaccharides (DLPs) displayed lower molecular weight, particle size and viscosity, but higher solubility. SEM and AFM revealed that US/H 2 O 2 degradation led to significant differences in the microstructure and solution conformation of LP. Moreover, LP and DLPs showed different proliferation effects on four lactobacilli and bifidobacteria strains, among which DLP-8 (degraded for 8 h) exhibited the strongest prebiotic activity. US/H 2 O 2 could be effectively applied to the degradation of LP to improve its physicochemical properties and bioactivities. • Ultrasound (US) assisted H 2 O 2 synergy degradation on Longan polysaccharide (LP) • US/H 2 O 2 degradation fits first-order kinetics and midpoint chain scission models. • Loose microstructure and low aggregation in degraded LP (DLPs) • Low molecular weight, viscosity, and particle size, and high solubility in DLPs • Best probiotic activity in DLP-8 (degraded for 8 h) to four probiotics strains