Abstract:In order to study the changes in the antioxidant activity of pomelo peel polysaccharides in the process of simulating in vitro gastrointestinal digestion，and to explore the effect of ultrasonic temperature，ultrasonic time，compound enzyme addition and enzymatic hydrolysis time on the yield of polysaccharides.The results showed that the optimum parameters of ultrasound-assisted enzymatic extraction of pomelo polysaccharide were ultrasonic temperature 30℃，ultrasonic time 40 min，compound enzyme addition amount 1.5%，enzymatic hydrolysis time 50 min.Under these conditions，the yield of pomelo polysaccharide was（27.23±0.21）%.The evaluation found that during simulated gastrointestinal digestion in vitro the digested products of pomelo peel polysaccharide had the ability of scavenging activities towards DPPH·，·OH and O2-·radicals.When oral saliva digestion was simulated for 20 min，the digested products had the highest DPPH·，·OH and O2-·radical scavenging abilities.While the highest DPPH·radical scavenging activities were observed when gastric digestion was simulated for 2 h.And the digested products had the highest DPPH·，·OH and O2-·radical scavenging capacity when small intestinal digestion was simulated for 8，6，4 h.In conclusion，pomelo peel polysaccharides still exhibited strong antioxidant activity after simulated digestion in vitro.