Effects of heat and ultrasonic treatments on the structure and processing characteristics of walnut protein

This study aimed to enhance the utilization efficiency of walnut protein (WP) and expand its application scope in the food industry. The impact of heat and ultrasonic treatments on the structure and processing characteristics of WP was investigated. Under processing treatments (dry-heat, moist-heat, microwave, ultrasound), sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed no significant alterations in polypeptide composition or formula weight distribution of the treated WP. Intrinsic fluorescence spectroscopy and scanning electron microscopy analyses demonstrated that heat and ultrasonic treatments stabilized the WP structure through disruption and reorganization of its tertiary conformation and surface morphology. After moist-heat treatment, the emulsifying activity, foaming capacity, and oil holding capacity of WP reached 87.66%, 85.30%, and 2.10 g/g, respectively. These values represent significant increases of 12.7%, 68%, and 12.9% compared to the untreated sample. After ultrasonic treatment, the foam stability of WP increased to 90.67%, representing an increase of 14.6% improvement compared to the untreated sample. These results indicate that heat treatment and ultrasonic treatment can significantly improve the processing characteristics of WP.