Study on the Optimization of the Preparation Process of Walnut Peptide and the Improvement of Memory Function

Objective: Taking walnut meal as raw material, the preparation process optimization of walnut peptide and its improvement of memory function activity were discussed. Methods: The preparation process of walnut peptide was optimized by single factor experiment and orthogonal experiment. At the same time, the water maze test, step-down test and passive avoidance test were used to evaluate the effect of walnut peptide on memory function. Female mice were divided into low, medium and high dose groups and blank control group. The intragastric administration doses were 1.33, 2.66 and 3.99 g/kg BW, respectively, and the control group was treated with distilled water. The mice were intragastrically administered for 30 days. The experiment was started after the last intragastric administration for 24 h. Results: The optimal enzymatic preparation process was as follows: citric acid concentration of pretreatment was 2%, alkaline protease dosage was 4%, solid-liquid ratio was 1:15, and enzymatic hydrolysis time was 4 h. Under these conditions, the yield of walnut peptide was 33.5% and the clarity was good. In the water maze test, the number of animals reaching the end of the middle dose group was significantly higher than that of the blank control group (P<0.05). In the passive avoidance test, the latency time of the high dose group was significantly prolonged, and the number of errors and error response rate were significantly reduced (P<0.01). Walnut peptide had the function of improving memory. Conclusion: In this study, the product clarity was improved while ensuring the quality of walnut peptide products.Meanwhile, the results of functional studies showed that walnut peptide could improve the memory from both active and passive avoidance.