紫外分光光度法对嫩肉粉中木瓜蛋白酶活力的测定方法研究

Determination of papain’s enzyme activity in meat tenderizer by UV spectrophotometry

木瓜蛋白酶具有分解蛋白为氨基酸的能力,是市场上嫩肉粉的主要成分。本文通过测定嫩肉粉中木瓜蛋白酶的酶活力大小,为判断嫩肉粉质量优劣提供参考依据。把嫩肉粉溶于盐酸半胱氨酸溶液,取该混合液与酪蛋白溶液反应10min,用紫外分光光度法测得反应所生成酪氨酸的含量。该方法具有较好的准确性和重现性,添加标准回收率为96.8%～105.8%;且步骤简明,所需测试仪器简单。在该方法条件下,每分钟水解酪蛋白生成1μg酪氨酸所需样品的量为1个酶活力单位。此种酶活力表述方式亦为国内关于各种酶活力的表述所常用,便于酶活力数据的比较与换算。通过测定,发现市售各种嫩肉粉中木瓜蛋白酶的酶活力参差不齐,则嫩肉粉对肉类的嫩化能力强弱亦有差别,体现在使用添加量的多少和对肉类浸泡时间的长短上。也有发现酶活力为0的,说明该产品中的木瓜蛋白酶已失去活力,或者根本没有添加木瓜蛋白酶,属于伪劣商品。

Papain can decompose protein into amino acids and is the essential ingredient of meat tenderizer.This paper studied the determination of papain＇s enzyme activity in meat tenderizer.The results can be used for estimating the quality of meat tenderizer.Dissolve meat tenderizer in L-cysteine hydrochloride monohydrate solution,mix the meat tenderizer solution and casein solution for chemical reaction 10 minutes and detect the content of reaction product tyrosine by UV Spectrophotometry.This method just needs simple equipment and is convenient,accurate and practical.The recovery rate was 96.8%～105.8%.Under the conditions,the amount of meat tenderizer for decomposing casein into 1μg tyrosine per minute is defined one enzyme activity unit.This kind of definition about enzyme activity is usually used in home,so the data is convenient for compare and conversion.After determination,we found the enzyme activity of papain in different meat tenderizers sold in market were different,and the tender capability of meat tenderizers were also different.So how much to use and how long to marinate the meat,different meat tenderrizers had different answers.We also found some enzyme activity was zero,that indicated the papain had lost its enzyme activity,or the meat tenderizer had not added papain.