薏苡仁醇溶蛋白水解工艺优化及其ACE 抑制活性的研究

目的：对薏苡仁中含量最丰富的醇溶蛋白水解条件进行优化，并对其水解产物进行血管紧张素转化酶（ACE）体外活性评价。方法：利用胃蛋白酶水解薏苡仁醇溶蛋白，邻苯二甲醛法测定水解度，通过正交实验优化醇溶蛋白酶解条件。酶解液超滤（截留分子量3 kD）冻干得到小分子量多肽，采用高效液相色谱法对其ACE 抑制活性进行测定。结果：薏苡仁醇溶蛋白酶解的最佳条件为：底物浓度1%，酶与底物浓度比1颐5，水解时间48 h；酶解物在0.1 mg·mL-1 浓度下体外ACE 抑制率为83.40%依0.93%。结论：醇溶蛋白水解产物表现出较强的体外ACE 抑制作用，为薏苡仁降压作用的进一步研究及功能食品的开发提供了理论支持。

Optimization on Hydrolysis Conditions of Coix Prolamin and Angiotensin-converting Enzyme Inhibitory Activity of Hydrolysates

This study was aimed to optimize the hydrolysis conditions of Coix prolamin, which occupied the highest content in total protein of it, and then evaluate the angiotensin-converting enzyme (ACE) inhibitory activity of the corresponding hydrolysates. Pepsin was used to hydrolyze prolamin and OPA method was applied to determine the degree of hydrolysis. The optimum conditions of hydrolyzing prolamin were obtained by orthogonal design subsequently. The ACE inhibitory activity of small molecular weight (less than 3 kD) peptides gained by ultrafiltration of the hydrolysates was assayed by RP-HPLC method. The result showed that the optimized hydrolysis conditions were substrate concentration of 1%, enzyme-to-substrate ratio of 1:5 and hydrolysis duration for 48 h. The hydrolysates exhibited an ACE inhibitory ratio of (83.40 ±0.93)% at the concentration of 0.1 mg·mL-1. It was concluded that prolamin hydrolysates displayed a high ACE inhibitory activity in vitro, which provided guidance for further research of antihypertensive component and development of functional food from Coix.