虾肉蛋白在乳酸菌发酵过程中的降解及其体外抗氧化活性的动态变化

Degradation of Shrimp Proteins during Fermentation with Lactic Acid Bacteria and Dynamic Changes in Their in Vitro Antioxidant Activity

本实验探究了在乳酸肠球菌发酵过程中虾肉肌原纤维蛋白和肌浆蛋白的降解及其产物(肽)抗氧化活性变化。结果表明,与未发酵时相比,随发酵时间的延长,两种蛋白的pH值均显著下降(P<0.05),蛋白酶活力均显著升高(P<0.05)。凝胶电泳结果表明,发酵使两种蛋白质均发生了降解,其中肌浆蛋白的降解程度更为明显。发酵后两种蛋白体系的2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)(2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid),ABTS)阳离子自由基清除率、1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率、Fe^(3+)还原力均显著增强(P<0.05),其中肌浆蛋白降解产物(肽)的抗氧化能力显著高于肌原纤维蛋白降解产物(P<0.05)。相关性分析显示,蛋白酶活力与肌浆蛋白的水解度及其产物的ABTS阳离子自由基清除率、DPPH自由基清除率以及Fe^(3+)还原能力呈显著正相关(P<0.05、P<0.01)。综上,通过乳酸肠球菌发酵虾肉蛋白,尤其是肌浆蛋白可得到具有较高抗氧化能力的肽。本研究可为水产加工(如鱼糜)过程中产生肌浆蛋白的充分利用和抗氧化活性肽的开发提供理论依据。

This study aimed to investigate the degradation of myofibrillar protein(MP)and sarcoplasmic protein(SP)during the fermentation of shrimp meat with Enterococcus lactis as well as the changes in antioxidant activity of the degradation products(peptides).The findings revealed that for both protein extracts,the pH significantly decreased with fermentation time(P<0.05),and the protease activity significantly increased(P<0.05)compared to that before fermentation.The results of gel electrophoresis showed that the fermentation resulted in degradation of both proteins,with more pronounced degradation of SP being noted compared to MP.The scavenging capacity against 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)radical cation and 1,1-diphenyl-2-picrylhydrazyl(DPPH)radical as well as Fe3+reducing power of the two protein extracts were significantly enhanced after the fermentation(P<0.05),and the antioxidant capacity of the peptides derived from SP was significantly higher than that of the peptides derived from MP(P<0.05).Correlation analysis showed a significantly positive correlation(P<0.05,and P<0.01)between protease activity and the degree of SP hydrolysis and the antioxidant activity of its degradation products.The results of this study indicated that peptides with high antioxidant capacity could be obtained from fermented shrimp proteins with E.lactis,and the peptides derived from SP had higher antioxidant activity.This study provides a theoretical basis for the full utilization of sarcoplasmic proteins produced during aquatic products processing(e.g.surimi)and the development of antioxidant peptides.