茶多酚钝化大豆胰蛋白酶抑制因子(STI)的研究

Inactivation of Soybean Trypsin Inhibitor by Tea Polyphenols

探索钝化豆类中胰蛋白酶抑制因子(STI)的生物抑制方法。通过测定胰蛋白酶活性来间接反映大豆STI的活性。在探明STI对胰蛋白酶抑制效果的基础上,进行了茶多酚(TP)在不同浓度、pH值、温度和时间条件下对鲜豆奶中的STI及STI标准品(KSTI及BBI)的钝化效果。结果表明:鲜豆奶中的STI和STI标准品均对胰蛋白酶活性具有很强的抑制作用;当鲜豆奶试液、KSTI及BBI的添加浓度分别为0.5 mg/ml、28.0μg/ml和21.0μg/ml时,对胰蛋白酶活性的抑制程度最大,抑制率分别为86.67%、100.00%和97.94%;当TP试液与鲜豆奶试液的比例为1∶2(体积比)时,TP对STI的钝化效果最好,抑制率为52.30%;当TP∶KSTI为25∶1(质量比)、作用温度45℃、pH4.5、作用时间90 min时,TP对KSTI的抑制率达83.15%;当TP∶BBI为20∶1(质量比)、作用温度40℃、pH4.5、作用时间60 min,TP对BBI的抑制率达76.58%。

A new method to inactivate the activities of the soybean trypsin inhibitor （STI） by tea polyphenols （TP） was developed . The activity of STI was indirectly valued by the activity of trypsin. Based on the inhibition effects of STI on trypsin, the inactivation of TP on STI in fresh soybean milk and on standard STI samples （KSTI and BBI） under various reaction conditions was studied. STI in fresh soybean milk and standard STI samples showed notable inhibition to trypsin. When the concentrations of soybean milk sample solution ,KSTI, and BBI were 0. 5 mg/ml,28. 0 μg/ml,and 21.0 μg/ml, the maxium inhibition to trypsin activity were 86. 67%, 100. 00%, and 97.94%, respectively. The maximum inactivation rate of STI by TP was 52. 30% when the ratio of TP sample solution to soybean milk sample solution was 1 ： 2 （ V/V ）. The maximum inactivation rate of KSTI by TP was 83.15% under the following conditions：the ratio of TP to KSTI（mg/mg） was 25 at pH4. 5 and temperature 45 ℃ for 1.5 h. For BBI,the inactivation rate was 76.58% when the ratio of TP to BBI was 20（mg/mg） ,at pH4. 5 and temperature 40 ℃ for 1 h.