低场NMR研究pH对肌原纤维蛋白热诱导凝胶的影响

 【目的】探讨pH对猪肉肌原纤维蛋白热诱导凝胶保水性及水的移动性影响。【方法】从猪肉中提取肌原纤维蛋白,用低场NMR（nuclear magnetic resonance）研究pH对肌原纤维蛋白热诱导凝胶中水的T2弛豫性质的影响。同时用离心法测量pH对肌原纤维蛋白凝胶保水性（water holding capacity,WHC）影响。【结果】NMR结果拟合后得到水有4个组分,合并为对应水的3种状态即不可移动水、可移动水和自由水。随着pH升高,pH偏离肌原纤维蛋白的等电点（pI）,代表可移动水的T2弛豫时间显著增加,其所占峰的面积和凝胶的WHC也随之增加。主成分分析结果发现,处于等电点附近的样品在样品评分图上与其它pH样品显著不同。【结论】凝胶保水性的增加主要是可移动水的增加,凝胶WHC增加的原因可能是肌原纤维凝胶后孔径增加,从而可以容纳更多的水。

Heat-Induced Gelation of Myofibrillar Proteins as Affected by pH-A Low Field NMR Study

【Objective】 The objective of this study is to discuss the effect of pH on the water holding capacity (WHC) and water mobility of pork myofibrillar protein heat-induced gelation. 【Method】 Myo?brillar proteins were extracted from porcine muscle, and their heat-induced gelation water properties were characterized using low-?eld nuclear magnetic resonance (NMR) T2 relaxometry. The WHC of the system was determined by centrifugation method. 【Result】 The NMR data was fitted to four components, which were merged into three states of water, i.e. immobile, mobile and free water. T2 relaxation time, peak area, and WHC which attribute to mobile water increased as pH away from pI, the principal components analysis result showed that the sample near pI clustered differently from others. 【Conclusion】 Improvement of WHC could be ascribed to the increasing of the mobile water, and the possible increase of the myo?brilar protein gel network pore diameter may leads to more water could be entrapped.