The Research Of Rice Protein Glycosylation Modification Of And Its In Vitro Antioxidant Activity

In this study,the rice protein was used as raw material,under the conditions of hot and humid,pumpkinpolysaccharide?dextran as reference?were used to make products of rice protein glycosylation grafting by Maillard reaction.The reaction process was optimized through response surface analysis method.The functional properties,antioxidant activity,and structureof optimization of the grafts was measured.Then preliminary discussed the protective effect on H₂O₂-induced HUVEC injury of the grafts.Based on the single experiment,used the grefting degree and solubility as the response value,the best conditions of rice protein glycosylation reaction were elected by Box-Behnken response surface analysis method.At last,the results showed optimum conditions of rice protein-pumpkin polysaccharide graft were pH 9.6,35 min,sugar:protein ratio=3:1,80?,under those condition,we received the actual value of solubility was 44.84%,the grefting degree was 29.43%were similared with the predicted value 46.0965%and 31.531%.So,it was the feasibility model.The results also showed optimum conditions of rice protein-dextran graft were pH 10.5,44 min,sugar:protein ratio=3:1,82?,under those condition,we received the actual value of solubility as 54.32%,the grefting degree was 42.31%were similared with the predicted value 53.2183%and 40.5854%.So,it was the feasibility model.It has been shown from the study that the measurement of antioxidant activity on rice proteins and their glycosylation grafts had ability to clear DPPH·?ABTS·+radicals and iron reduction capacity,and increased obviously with its concentration.The ability ordered by rice protein-pumpkin polysaccharide graft,protein-dextran graft and rice protein.At the highest concentration,the DPPH radical scavenging capacity of rice protein-pumpkin polysaccharide graft could be reached 89.33%BHT which was recognized as antioxidants,and 49.83%higher than the rice protein.The ABTS·+radical scavenging capacity of its could be reached 65.2%Vc which was pured,and its iron reduction capacity is a tendency for 0.917 mmol/L of FeSO4 with the concentration of 10 mg/mL.It has been shown from the measurement of functional properties on rice proteins and their glycosylation grafts that the grafts had a obviously improvement in the solubility,and compared with rice protein,they were higher than 32.27%and 41.75%respectively.The Emulsification of two grafts were little upgrade,but also promoted respectively 6.17%and 9.1%.And the foamability of two kinds of grafts were little difference,about 15%higher than that of rice protein.SDS-PAGE analysis found that glycosylation reaction occurs mainly in low molecular weight subunits section,and after glycosylation,the subunit molecular weight of two grafts were increased significantly.DLS analysis discovered that the order of the average particle size between them were rice protein-pumpkin polysaccharide graft?218 nm?,rice protein-dextran graft?162.4 nm?,rice protein?149.6 nm?,those also greater than the pumpkin polysaccharide?172.4 nm?and dextran?33.86 nm?.The data also indirectly proved that after the rice protein glycosylation reaction,the molecular weight of rice protein increased.Through the SEM observant-ions,We learnt that after glycosylation reaction the proein'sstructure became loose and had a lot of honeycomb holes.So,its solubility improved.The FTIR showen that two grafts had the sugar absorption peaks,but also had absorption peaks of protein phthalein amine compounds.It has been shown from the preliminary discussion on protective effects of two grafts through H₂O₂ injury HUVEC that the optimum concentration of H₂O₂ was 300?mol/L.The MTS test result displaied that the best protein concentrration of two grafts and rice protein were0.18mg/mL.Light and fluorescence microscope observa-tion showed,the number of cells of rice protein-dextran graft and rice protein-pumpkin polysaccharide graft between injury group and the control group.Its cell morphology was similar to control group.Several cells was observed with a small amount of damage or apoptosis.Itsillustrated that both of them had protective effect,but the rice protein-pumpkin polysaccharide graft was better than rice protein-dextran graft.Therefore,we launched that rice protein and polysaccharide could happen glycol-sylation reaction.The grafting degree of protein-pumpkin polysaccharide graft was lower than rice protein-dextran graft,but the antioxidant activity of it better than rice protein-dextran graft,and obviously better than that of rice protein.The grafts had an obvious protective effect on HUVEC damage model induced by H₂O₂.This would be provided the based study on the improving functional properties of rice protein and reference for development and a new natural antioxidant.It also provided the theore-tical basis for the application of rice protein in the food and pharmaceutical areas.