超声波预处理酶解制备茶渣蛋白ACE抑制肽及其活性分析

血管紧张素转换酶（Angiotensin-I Converting Enzyme，ACE）在血压调节中扮演重要角色，抑制其活性有利于维持血压平衡。食源性ACE抑制肽具有安全、易吸收的特点，受到广泛关注。本研究旨在从茶渣蛋白中获得一种具有高ACE抑制活性的新肽。以ACE抑制率为指标，通过对三种超声方式的比较，确定最佳超声方式；以单因素实验为基础，进行响应面优化确定最佳超声波预处理参数；酶解液分离纯化运用超滤的方法，并对截留分子量小于3 kDa组分进行稳定性分析。结果表明，超声波预处理为最佳处理方式，得最优条件为超声功率300 W、超声温度45 ℃、超声时间25 min。在最佳超声波预处理条件下，ACE抑制率为64.8%，相比于未超声组54.1%提高了10.7%；当截留分子量小于3 kDa时，ACE抑制肽的抑制率为82.3%，相比于原始酶解液提高了17.5%。当温度30 ℃升温至90 ℃，ACE抑制肽的抑制率从82.3%降低至78.3%，减少了4.3%；酸碱度、盐溶液变化其对ACE抑制率表现稳定；模拟消化环境中8 h后，ACE抑制率从82.3%降为62.3%。

Ultrasonic Pre-treatment for the Preparation of ACE-inhibitory Peptides from the Tea Residue Protein through Enzymatic Hydrolysis and Its Stability

Angiotensin-converting enzyme (ACE) plays an important role in blood pressure regulation, and inhibition of its activity is beneficial to maintain blood pressure balance. Food-derived ACE inhibitory peptides have attracted wide attention due to their safety and easy absorption. This study aimed to obtain a new peptide of high ACE inhibitory activity from tea residue protein. With the ACE inhibitory rate of ACE inhibitory peptides as the index, ultrasonic pre-treatment of tea residue protein was the best method through comparison of three ultrasonic methods. Response surface optimization was used to determine the optimal ultrasonic pretreatment parameters based on the single-factor tests. The enzymatic solution was separated and purified by ultrafiltration, and the stability of components with molecular weight less than 3 kDa was analyzed. The results showed that the optimum ultrasonic pretreatment conditions were ultrasonic power 300 W, ultrasonic temperature 45 °C, ultrasonic time 25 min. Under the optimal conditions, the ACE inhibitory activity was 64.8%, which was 10.7% higher than 54.1% in the control group (without ultrasonic). When the molecular weight cut-off was less than 3 kDa, the inhibition rate of ACE inhibitory peptide was 82.3%, which was 17.5% higher than that of the original hydrolysate. When the temperature rose from 30 to 90 oC, the inhibition rate of ACE inhibitory peptide decreased from 82.3% to 78.3%. The peptide showed stable ACE inhibition rate in pH and salt solution. The inhibition rate of ACE inhibitory peptide decreased from 82.3% to 62.3% after 8 h in simulated digestion environment.