Abstract: In order to increase the added value of shrimp processing by-products, this study used protease to hydrolyze shrimp shell protein and prepare a freshness enhancing, and unique flavor umami peptide.The effects of feed liquid ratio, enzyme dosage, enzyme hydrolysis time, and the temperature on the enzymatic hydrolysis efficiency of shrimp shells were studied using protein hydrolysis degree, solid dissolution rate, and soluble calcium ion content as indicators. Based on the single- factor experiment, the optimal enzymatic hydrolysis process conditions were determined through orthogonal optimization, and the free amino acids and volatile flavor components in the enzymatic hydrolysis solution were analyzed.The results showed that under the conditions of a solid-liquid ratio of 1∶2 and an initial pH of 7.0, adding 4 000 U/g of neutral protease resulted in a hydrolysis degree of 18.76% after 5 hours of enzymatic hydrolysis at 50 ℃. Fifteen amino acids were detected in the enzymatic hydrolysate, with glutamic acid accounting for 12.26%, highlighting its distinct flavor characteristics. 24 flavor components with high content were detected in the enzymatic hydrolysis solution, among which pyrazine components accounted for 40.08% and benzaldehyde content was 33.48%, which are characteristic aromas in the enzymatic hydrolysis products of shrimp shells.

Key words: shrimp shell, neutral protease, enzymatic hydrolysis, amino acids, volatile flavor components