超声处理对菜籽蛋白酶解效果的影响

以双低菜籽饼粕蛋白为原料，以常规酶解为对照，以酶解产物的抑制活性为指标，分别考察了超声预处理蛋白酶、超声预处理蛋白原料和酶解过程前期施加超声3种超声处理方式对双低菜籽蛋白酶解制备ACEI 活性肽效果的影响。结果表明，3种超声辅助方式都能有效地促进菜籽饼粕蛋白的酶解，提高产物的ACE抑制活性，其中超声预处理蛋白原料效果最为明显。这种方式的最佳参数为：超声频率20 kHz、超声时间 30 min、超声功率1250 W、作用时间4 s、间歇时间2 s，该条件下酶解产物对ACE的抑制率从对照组的70.83%提高到92.97%，肽得率从29.6%提高到41.4%，半抑制浓度IC50从3.57 mg/mL降到2.48 mg/mL。这表明脉冲超声辅助酶解法是一种高效制备双低菜籽ACEI肽的方法。

Effect of ultrasonic treatment on rapeseed protein enzymolysis

Angiotensin-Converting Enzyme Inhibitor(ACEI) peptides were prepared from double-low rapeseed protein by pulsed ultrasonic-assisted enzymolysis. Three reaction models, which included ultrasonic pretreatment of proteinase followed by enzymolysis (UPPE), ultrasonic pretreatment of double-low rapeseed protein solution followed by enzymolysis (UPRPE) and ultrasonic-assisted enzymolysis processes during previous period (UAE), were investigated. The inhibitory activity of hydrolysate to Angiotensin-Converting Enzyme(ACE) was the index. Traditional enzymatic hydrolysis (TE) without ultrasonic treatment was conducted as a control test. Results showed that three models all had significant effects, and UPRPE was the best. The optimum parameters of UPRPE obtained by orthogonal experiments were: ultrasonic frequency 20 kHz, ultrasonic treatment time 30 min, ultrasonic power 1250 W, on-time of the pulse 4 s and off-time 2 s. Compared with the traditional enzymatic hydrolysis, the inhibitory activity of the hydrolysate to ACE increased from 70.83% to 92.97%, ACEI peptide output raised from 29.6% to 41.4% and half inhibiting concentration IC50 value decreased from 3.57 mg/mL to 2.48 mg/mL under the optimum UPRPE conditions. These results prov that the pulsed ultrasonic-assisted enzymatic hydrolysis is a highly efficient method for preparing ACEI peptides from double-low rapeseed protein.