限制性酶解改性鲢鱼肌原纤维蛋白功能性质的研究

Functional Properties of Silver Carp Myofibril Protein by Limited Enzymolysis

为了提高肌原纤维蛋白的功能,采用不同酶(胰蛋白酶、中性蛋白酶及复合酶)对鲢鱼肌原纤维蛋白进行限制性酶解改性,在酶解过程中,通过对水解度、蛋白分子量大小、肌原纤维形态学变化及功能性质进行测定与观察,探究其功能性质随改性程度的动态变化规律。结果表明,随着酶解的进行,鲢鱼肌原纤维长度逐渐变短,蛋白的溶解性逐渐增加,酶解80 min时,肌原纤维主要以1~3个肌节形式存在,3组蛋白质的溶解性分别达到61.2%、36.9%和58.4%;3组酶解蛋白的乳化性和起泡性随反应时间的增加均呈先增后减的趋势,其中复合蛋白酶酶解40 min时乳化活性及起泡性最大,分别达到65.5m2·g-1和110%,胰蛋白酶改性20min时蛋白乳化稳定性最好,可达46.6 min,远大于未酶解蛋白的14.7 min。分子量分布及SDS-PAGE图谱显示,蛋白平均分子量均为20~30 k Da,水解度均低于5%。综上,酶的选择对溶解性的改善至关重要,而乳化性及起泡性的改善不仅需要对酶进行筛选,还需对水解度进行严格限制,保持酶解后蛋白具有较大的分子量,避免酶解过度。本研究结果为蛋白质乳化性和起泡性的改性研究提供了参考。

In order to improve the functional properties of silver carp myofibrillar protein,different proteases（ trypsin,neutral protease,and neutral protease-trypsin system） were adopted in the limited enzymatic hydrolysis. The degree of hydrolysis,molecular weight of protein hydrolysate,morphological analysis and functional properties were determined.The dynamic changes of functional properties during enzymatic hydrolysis were revealed. The results were shown that myofibrils were shorten obviously during the hydrolysis of protein. The solubility of hydrolysate also increased rapidly.The sarcomere amount of myofibril protein was mainly 1 to 3 after enzymatic hydrolysis of 80 minutes. The solubility of hydrolysates hydrolyzed by trypsin,neutral protease and protamex after 80 min of hydrolysis reached to 61. 2%,36. 9%,58. 4% respectively. The emulsifying properties and foaming properties have a tendency of firstly increasing and then decreasing. The hydrolysate of protamex at 40 minutes of hydrolysis exhibited maximum emulsifying activity（ 65. 5m2·g- 1） and foaming properties（ 110%）,while the hydrolysate of trypsin exhibited maximum emulsifying stability（ 46. 6 min） at 20 minutes of hydrolysis. SDS-PAGE revealed that all of the myofibril hydrolysates had a 20 ~30 k Da of average molecular weight and a 5% of hydrolysis degree. Screening of protease is essential to the improvement of protein solubility. The controlling of hydrolysis degree to maintain higher molecular weight hydrolysate is necessary for the modification of protein emulsifying properties and foaming properties. The outcome can provide scientific basis for the enzymatic modification of myofibril protein.