乳清分离蛋白酶解制备抗氧化和ACE抑制活性产物

Antioxidant and ACE inhibition Activity of Hydrolysates Obtained from Whey Protein Isolate

以乳清分离蛋白为原料,通过对肽浓度、游离氨基酸含量及水解度的研究,探讨了碱性蛋白酶Alkaline、中性蛋白酶NPU、肽酶AX和风味蛋白酶Flavourzyme对乳清蛋白酶解的影响。在优化碱性蛋白酶Alkaline水解条件的基础上,考察了中性蛋白酶NPU、风味酶Flavourzyme添加时间,获得了复合酶分步酶解工艺:酶解温度55℃,加入1.5%Alkaline([E/S]),维持pH8.5酶解10 min,待pH7.2时加入1%NPU([E/S]),酶解240 min,加入1%Flavourzyme([E/S])继续酶解20 min。在此条件下,肽浓度达到60 g/L以上,游离氨基酸含量为4348 mg/kg。获得的酶解产物基本无苦味。酶解物分子量主要分布在<1 kDa(69.62%)。酶解产物具有ABTS自由基清除和ACE抑制活性,IC50值分别为1.02(0.377μmol Trolox当量/mg)和1.38 mg/mL。综上,采用复合酶酶解乳清分离蛋白可获得具有抗氧化活性和ACE抑制活性产物,为乳清酶解物在功能食品或保健品领域的运用提供科学参考。

The effects of alkaline,NPU,AX and flavourzyme on the peptide concentration,free amino acid content and degree hydrolysis of the hydrolysates from the WPI(whey protein isolate)were investigated. Based on the optimized conditions of alkaline,the addition time of NPU and flavourzyme were investigated and the optimal conditions of three-step-hydrolysis of composite enzyme were obtained. The optimal conditions of three-step-hydrolysis of composite enzyme were temperature 55 ℃,1.5% alkaline([E/S]),pH8.5,and hydrolysis time 10 min. When pH was 7.2,1% NPU([E/S])was added. After WPI hydrolysis for 240 min with alkaline and NPU,1% flavourzyme([E/S])was added and hydrolysis continued for a further 20 min.The non-bitter WPI hydrolysates contained peptides(>60 g/L)and free amino acids(4348 mg/kg)with molecular weights below 1 kDa(69.52%).The IC50 of ABTS and ACE were 1.02(0.377 μmol Trolox eq/mg)and 1.38 mg/mL,respectively. The WPI could be hydrolyzed by three-step-hydrolysis of composite enzyme to obtain the hydrolysates with antioxidant activity and ACE inhibition activity. This study laid a foundation for whey hydrolysates utilization in functional foods and health foods.