超高压及植物油添加量对兔肌球蛋白热凝胶特性的影响

Effects of Ultra-High Pressure Treatment and Vegetable Oil Addition on the Thermal Gelling Properties of Rabbit Myosin

为研究超高压处理及植物油添加量对兔肌球蛋白热凝胶特性的影响,在不同压力条件(100、150、200 MPa)下对兔肌球蛋白进行10℃、2 min超高压处理,然后分别添加不同体积分数(0%、10%、20%、30%)的大豆油和磷酸盐缓冲液制备乳化体系,再利用程序升温(1℃/min)制备凝胶,并以未经高压处理的肌球蛋白作为空白对照。利用流变仪、质构分析仪、扫描电子显微镜、低场核磁共振分析仪等对热凝胶的储能模量G′、损耗模量G″、凝胶强度、保水性、微观结构和弛豫时间等指标进行测定。结果表明:与空白对照组相比,高压处理及添加油脂使兔肌球蛋白热凝胶的G′、G″、凝胶强度、保水性等指标均明显增加;通过扫描电子显微镜观察到经复合处理的凝胶三维网络结构变得更加致密和紧凑,低场核磁共振分析结果显示凝胶基质中的自由水相对含量随着压力的增加逐渐减少,不易流动水质子结合程度增加,结合水组分相对含量明显增多。在相同压力处理条件下,兔肌球蛋白热凝胶的G′、G″、凝胶强度、保水性随着油脂添加量的增加而增大,即0%处理组<10%处理组<20%处理组<30%处理组,且相互之间差异显著(P<0.05);其中,在200 MPa下添加30%油脂时,兔肌球蛋白热凝胶性能最好。综上,适当的高压处理结合油脂的添加,一定程度增强了蛋白质和脂肪的相互作用,改变了肌球蛋白热凝胶的微观结构和水分分布状态,从而表现出相应流变特性、质构特性、保水性等凝胶特性的变化,进而对改善兔肌球蛋白热凝胶的功能特性发挥积极作用。

To investigate the effects of ultra-high pressure(UHP)treatment and vegetable oil addition on its heat-induced gel properties,rabbit myosin was subjected to UHP treatments(10℃/2 min)at different pressure levels(100,150 and 200 MPa),and then mixed with different amounts(0%,10%,20%and 30%)of soybean oil and phosphate buffer to prepare emulsion systems,whose heat-induced gelation was carried out at a programmed heating rate of 1℃/min.Myosin not treated by UHP served as control.The storage modulus G′,loss modulus G″,gel strength,water-holding capacity(WHC),microstructure and relaxation time spectra of heat-induced myosin gels were measured by rheometer,texture analyzer,scanning electron microscope(SEM)and low-field nuclear magnetic resonance spectroscopy(NMR).The results showed that compared with the control group,the storage modulus,loss modulus,gel strength and WHC of heat-induced myosin gels were increased significantly by high pressure treatment and the addition of soybean oil.SEM revealed that the three-dimensional network structure became denser and more compact.The NMR analysis showed that the relative content of free water in the gel matrix gradually decreased with an increase in pressure,and the degree of proton binding of immobilized water and the relative content of bound water significantly increased.Under the same pressure,the G′,G″,gel strength and WHC increased with increasing addition of soybean oil,showing significant differences among addition levels(P<0.05).The 200 MPa+30%soybean oil group had the best heat-induced gel properties.Therefore,appropriate high pressure treatment combined with the addition of soybean oil enhanced the interaction between protein and fat,and changed the microstructure and water distribution state and consequently gel properties such as rheological properties,texture and WHC of heat-induced myosin gels,which played a positive role in improving the functional properties of heat-induced rabbit myosin gels.