Hydroxyl radical-induced early stage oxidation improves the foaming and emulsifying properties of ovalbumin

As the most abundant protein in chicken eggs, ovalbumin plays an important role in the processing of high value-added poultry products. The present study investigated the effects of hydroxyl radical-induced early stage oxidation on the physicochemical and interfacial properties of chicken egg white ovalbumin. Protein carbonyl content of ovalbumin increased (from 0.78 to 1.13 nmol/mg) with the oxidation time (0-5 h), while free sulfhydryl content (from 0.43 to 0.09 nmol/mg) and free amino group content (from 0.49 to 0.43 nmol/mg) decreased. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed that the exposure of ovalbumin to hydroxyl radicals caused self-cross-linking and resulted in the formation of dimers and trimers. Accompanied by these changes, the surface hydrophobicity of ovalbumin was enhanced about 1.5-fold with the deepening of oxidation, and the value of zeta potential became more negative (from -7.15 to -20.51 mv). About 2 h of moderate oxidation improved the foaming and emulsifying properties of ovalbumin (1.2-fold to 1.8-fold), while excessive oxidation (3 h) decreased these interface properties. Hydroxyl radical-induced oxidation changed the surface chemical groups and structures of ovalbumin, thereby affecting the surface properties. The foaming and emulsifying properties of ovalbumin could be improved by oxidation, increasing the application possibilities of ovalbumin in the food interface system.