Effect Of High Pressure Treatment On Functional And Structural Properties Of Rice Bran Protein

Rice bran protein was extracted from rice bran by the method of alkali extraction,and followed by high pressure treatment.The functional and structural properties of rice bran protein were investigated.The effect of high pressure on glycosylation and the functional properties of rice bran albumin with glucose were investigated as well.The main results were as follows:Comparing with the untreated sample,HP treatment at 100 and 200 MPa significantly improved the solubility,while water absorption capacity and foaming capacity both increased with the increasing of pressure.The oil absorption capacity of rice bran protein under HP treatment was improved and reached the maximum at 200 MPa,while emulsion stability reached the maximum at 400 MPa.The emulsifying activity and foam stability of treated samples were significantly higher and least gelation concentration was lower after treatment,but none of them showed any specific trend with pressure level.The FTIR spectra,circular dichroism spectroscopy,particle size,surface hydrophobicity and intrinsic fluorescence emission spectroscopy were used to detect the structural properties of HP-treated rice bran protein.HP treatment lead to the-OH?-CH?C=O?C-N stretching vibration absorption peaks shifted,a-helix content increased,surface hydrophobicity increased and relative fluorescence intensity first increased then decreased.The HP treatment can partially unfold the rice bran protein structure,leading to more hydrophobic groups exposed and as a result improved the functional properties of rice bran protein.The absorbance of A294 and A420 was used to detect the early and advanced stage of Maillard reaction between rice bran albumin.and glucose.Both the data were reduced after high pressure,indicating that HP treatment suppressed the glycosylation reaction.The same conclusion can be drawn by calculating the content of free amino groups and the degree of graft during the reaction.The functional properties of rice bran albumin and glucose conjugate weremeasured.The solubility of rice bran albumin was improved at 100 MPa,but the solubility decreased with the increasing of pressure.The emulsifying activity and emulsion stability were not significantly different from the control at lower pressure.The foaming capacity and oil absorption capacity increased with the increasing of pressure and reached the maximum at 400 MPa,while water absorption capacity reached the maximum at 300 MPa.