Abstract:This experiment adopted ultrasonic-microwave synergistic method to extract the protein of walnut and optimized the best method.Factors such as ratio of material to liquid，pH，ultrasonic power and microwave power were selected as the factors affecting the extraction rate，comparison of the effect of different single factors on the extraction rate.The isoelectric point of walnut protein，the solubility and denaturation temperature，different protein concentrations，different pH and different temperature conditions were studied.The results showed that the optimum extraction conditions were：the ratio of material to liquid was 1 ∶20（g/mL），pH9.0，ultrasonic power was 400 W，and microwave power was 200 W.Under this condition，the maximum extraction rate was （93.48±1.02）%，The isoelectric point of walnut protein was pH5.0.When the protein concentration was 20 mg/mL，the solubility presented the largest and the optimum solution temperature was 70℃.The solubility was the worst at the isoelectric point of the protein，and the solubility increases with the pH increases.The results of differential calorimetry showed that the walnut protein had an obvious minimum absorption peak at 83.80℃，that was the walnut protein denaturation temperature.