为了深入了解蛋白氧化对凝胶特性的影响,文中研究了氧化对乳清蛋白凝胶质地和流变学特性变化的影响,以此探讨乳清蛋白氧化对其功能性质的影响机制。试验采用羟基自由基氧化体系,在不同H2O2浓度(1-20mmol/L)及不同FeCl3浓度(0.1-1mmol/L)对乳清蛋白分别氧化3h,通过质构仪和流变仪对凝胶特性进行研究。结果显示:同未氧化乳清蛋白相比,在所有氧化条件下,凝胶硬度降低90%以上,贮藏模量(G′)值降低17%以上,复合模量(G*)值降低20%以上;高浓度氧化条件下,弹性降低20%以上,凝胶形成温度明显降低。结果表明,氧化对蛋白凝胶质地和凝胶形成能力起着很大的破坏作用,因此,必须控制蛋白氧化的发生。

In order to understand the effects of protein oxidation on gels properties and the mechanism of the changes of protein functionality,we studied gels texture and rheological properties of WPI gels. In this paper,Whey protein isolate (WPI) was exposed to a hydroxyl radical-generating system (HRGS) at different concentration of H2O2(1-20 mmol/L)or FeCl3(0.1-1 mmol/L)for 3 h. The results revealed that the hardness of gels decreased more than 90%,the storage modulus(G' value) decreased more than 17%,and the complex modulus (G* value) decreased more than 20% in all oxidative conditions compared with non-oxidized protein gels; under higher concentration of oxidants,the gels springiness decreased more than 20% and gel forming temperature decreased remarkably. These experiments suggested that oxidative damage to the gels texture and the gels formation ability of WPI was significant. Therefore,protein oxidation should be controlled.