Zero Hunger (SDG 2), Good Health & Well-being (SDG 3)
In vitro antioxidant activity of rice protein and soy protein
Kesia Bess* Guyana
Rice protein (RP) and soybean protein (SP) are major plant proteins that possess health care and disease prevention functions. This study was conducted because of the lack of comparative studies on the in vitro antioxidant activities of rice protein and soy protein. With an in vitro digestion model, which involved sequential 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, with the animal protein casein used as a control. Also, the 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 of the protein hydrolysates 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% and 12.91% - 36.61%, respectively (P < 0.05). The findings of this study also indicate that both rice protein and soybean protein possess better in vitro antioxidant activity than casein and that the antioxidant activity of rice protein was superior to soybean protein. Compared with casein, the ability of rice protein to scavenge nitric oxide radicals was 19.21% - 45.86% more effective (P < 0.05), whereas the ability of soybean protein to scavenge nitric oxide radicals was 10.75% - 31.85% higher (P < 0.05). The ability of rice protein to scavenge hydrogen peroxide in comparison to casein, was higher by 23.29% - 53.78% (P < 0.05), while the scavenging ability of soybean protein for hydrogen peroxide was 10.34% - 42.74% higher than casein (P < 0.05). The scavenging activity of rice protein and soybean protein for superoxide radicals were also significantly better than casein with 16.09% - 58.78% higher and 11.27% - 46.82% higher respectively. The chelation of Fe2 + by rice and soybean protein after in vitro digestion also exceeded that of casein by 18.72% - 36.14% (P < 0.05) and 13.51% - 33.64% (P < 0.05) respectively. While for Cu2 + , chelation by rice protein was 19.84% - 138.84% (P < 0.05) higher than casein and 17.31% - 49.86% (P < 0.05) higher for soybean protein. The in vitro reducing power of rice protein compared with casein, was higher by 49.44% - 59.38% (P < 0.05) and soybean protein was 38.67% - 50.00% higher than casein (P < 0.05). 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 20.83% - 140.00% (P < 0.05) higher than casein. Overall, the different antioxidant responses of the protein hydrolysates under simulated digestion were reliant on the extent of pepsin-pancreatin digestion, and thus the digestibility is an essential factor in modifying the antioxidant activity of proteins.
P05
© The Author(s), 2023
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