In Vitro Antioxidant Activity Of Rice Protein And Soy Protein

Rice protein?RP?and soybean protein?SP?are major plant proteins that possess health care and disease prevention functions.This study was conducted due to the lack of comparative studies on the in vitro antioxidant activities of rice protein and soy protein.For this reason,the animal protein casein?CAS?was used as a control while rice protein and soybean protein were the research objects in this research undertaking.Through the use of an in vitro digestion model,which involved pepsin digestion for 1-2 h and pancreatin digestion for 1-6 h,the in vitro digestibility of casein,rice protein and soy protein was determined.Also,their free radical scavenging activity of superoxide radical,nitric oxide radical and hydrogen peroxide?H₂O₂?,their metal ion(Fe²⁺,Cu²⁺)chelating activity,reducing power and total antioxidant capacity at different stages of digestion were analysed.The results show that casein possesses better digestibility than rice protein and soybean protein during different digestive stages with pepsin and pancreatin.When compared with casein,the digestibility of rice protein and soybean protein were lower by 6.78%-32.24%and12.91%-36.61%,respectively?P<0.05?.After digestion with pepsin and pancreatin,the ability of rice protein to scavenge superoxide radicals was 16.09%-58.78%higher than casein?P<0.05?and the ability of soybean protein to scavenge superoxide radicals was higher than casein by 11.27%-46.82%?P<0.05?.The superoxide radical scavenging activity of rice protein was better when compared to soy protein.Compared with casein,the ability of rice protein to scavenge nitric oxide radicals was 19.21%-45.86%more effective?P<0.05?,and the ability of soybean protein to scavenge nitric oxide radicals was 10.75%-31.85%higher?P<0.05?;and the ability of rice protein to scavenge nitric oxide radicals was better than that of soybean protein.The ability of rice protein to scavenge hydrogen peroxide in comparison to casein,was higher by 23.29%-53.78%?P<0.05?,whereas the scavenging ability of soybean protein for hydrogen peroxide was 10.34%-42.74%higher than casein?P<0.05?.The hydrogen peroxide scavenging ability of rice protein was better than soybean protein.After digestion with pepsin and pancreatin,the ability of rice protein to chelate Fe²⁺in comparison to casein was higher by 18.72%-36.14%?P<0.05?,and the ability of soybean protein to chelate Fe²⁺was 13.51%-33.64%?P<0.05?higher than casein.The Fe²⁺chelating ability of rice protein was better than soybean protein.Similarly,when compared with casein,the ability of rice protein to chelate Cu²⁺was higher by 19.84%-138.84%?P<0.05?,while the ability of soybean protein to chelate Cu²⁺was higher than casein by 17.31%-49.86%?P<0.05?.The Cu²⁺chelating ability of rice protein was better than soy protein.After digestion with pepsin and pancreatin,the in vitro reducing power of rice protein compared with casein,was higher by 49.44%-59.38%?P<0.05?,and the in vitro reducing power of soybean protein was 38.67%-50.00%higher than casein?P<0.05?.The in vitro reducing power of rice protein was better than soy protein.When compared with casein,the total antioxidant capacity of rice protein was 61.90%-170.00%higher?P<0.05?,while the total antioxidant capacity of soybean protein was higher than casein by 20.83%-140.00%?P<0.05?.The total antioxidant activity of rice protein was better than soy protein.The results of this study showed that both rice protein and soybean protein possessed better in vitro antioxidant activity than the animal protein casein,and that the antioxidant activity of rice protein was superior to soybean protein.