碱性蛋白酶水解大豆蛋白过程的拟合及水解产物性质的研究

Analog of SPI hydrolysis by Alcalase and properties of hydrolysates

采用Alcalase碱性蛋白酶在50、60℃下以不同酶底比(1∶100、2∶100和3∶100)分别制备水解度(DH)为5%、10%和15%的大豆蛋白水解产物。考察水解反应动力学以及水解产物的DPPH自由基清除率和三氯乙酸可溶性氮含量,并且采用HPLC表征水解产物相对分子质量变化。结果表明:碱性蛋白酶在所考察的条件下水解大豆蛋白,符合指数形式动力学方程;水解产物水解度从5%增加到15%,DPPH自由基清除率和三氯乙酸可溶性氮含量分别由17.07%、16.28%增加到31.84%、64.85%;大豆蛋白经碱性蛋白酶水解至相同水解度时,在同一温度下,随着酶底比的增加,水解产物的DPPH自由基清除率和三氯乙酸可溶性氮含量增加,水解产物中相对分子质量大于10 k D的肽段比例逐渐减小,小于0.5 k D的肽段比例逐渐增大。同一种酶水解同一种蛋白质,虽然水解反应动力学均符合指数形式动力学方程,但是当大豆蛋白被水解至相同水解度时,不同条件下制备的水解产物的性质与结构均有显著性差异。

Soybean protein hydrolysates with degree of hydrolysis （DH） 5% ,10% and 15% were pre- pared respectively by Alcalase at 50 ℃ and 60 ℃ with different enzyme - substrate ratios （ 1 ： 100, 2： 100, 3：100）. Hydrolysis reaction kinetics, DPPH free radical scavenging rate and trichloroacetic acid （TCA） soluble nitrogen content of the hydrolysates were studied, and the change of relative molecular weight of the hydrolysates was characterized by HPLC. The results showed that soybean protein hydrolyzed by Alca- lase under the experimental conditions was in line with the exponential kinetic equation. With the degree of hydrolysis of hydrolysates increased from 5% to 15% , DPPH free radical scavenging rate and TCA sol- uble nitrogen content increased from 17.07% ,16.28% to 31.84%, 64.85%, respectively. When soy- bean protein was hydrolyzed by Alcalase to the same degree of hydrolysis, at the same temperature, DPPH free radical scavenging rate and TCA soluble nitrogen content of hydrolysates increased and the proportionof peptides with relative molecular weight above 10 kD in hydrolysates decreased, while the proportion of peptides with relative molecular weight below 0. 5 kD increased with the enzyme - substrate ratio increased. Although hydrolysis re- action kinetics was in line with the exponential ki-netic equation, the properties and molecular structure of hydrolysates prepared under different conditions were significantly different when soybean protein was hydrolyzed to the same degree of hydrolysis.