Effects of rice bran rancidity on oxidation, structural characteristics and interfacial properties of rice bran globulin

Rice bran globulin was prepared by rice bran with different storage periods and evaluated for its oxidation degree, structural characteristics and interfacial properties. As storage time of rice bran extended, protein carbonyl content gradually increased from 1.68 to 11.20 nmol/mg, and sulfhydryl content decreased from 21.10 to 6.40 nmol/mg, indicating rice bran rancidity caused rice bran globulin oxidation. Other structural indexes showed rice bran globulin oxidation caused significant changes in secondary structure of rice bran globulin, and strengthening disulfide bonds induced rice bran globulin further aggregation and cross-link. Besides, increasing storage time of rice bran led to the loss of foaming capacity, foam stability, emulsifying activity and emulsion stability of rice bran globulin. Correlation analysis between interfacial properties and oxidation extent along with structural characteristics of rice bran globulin revealed that protein oxidation extent, surface hydrophobicity, protein solubility and zeta potential were highly related with the interfacial properties of rice bran globulin.