pH对肌原纤维蛋白二级结构及其热诱导凝胶特性的影响

Studies on the Secondary Structure and Heat-Induced Gelation of Pork Myofibrillar Proteins as Affected by pH

【目的】研究pH对猪肉肌原纤维蛋白二级结构α-螺旋及其热诱导凝胶硬度、保水性及微观结构的影响。【方法】采用圆二色谱(circular dichroism,CD)测定不同pH下,猪肉肌原纤维蛋白α-螺旋含量的变化;用物性测试仪测定相应pH下肌原纤维蛋白热诱导凝胶的硬度,用离心法测定其保水性,同时利用扫描电镜拍摄其微观结构。【结果】随着pH偏离肌原纤维蛋白等电点(pI)向中性范围靠近,其α-螺旋含量及其热诱导凝胶的保水性都逐渐增大;而凝胶硬度在pH6.0时达最大值;在远离等电点的中性条件下,肌原纤维蛋白凝胶具有较高有序性的微观结构,而且结构均匀,酸性条件下凝胶的微观结构有序性低,不均匀,且存在聚合物。【结论】猪肉肌原纤维蛋白α-螺旋含量与其热诱导凝胶保水性呈正相关关系;蛋白含天然结构α-螺旋较多时,凝胶微观结构比较有序,反之,凝胶微观结构比较粗糙。

【Objective】 The objective is to study the effect of pH on the secondary structure,α-helix of pork myofibrillar protein,and the hardness,water holding capacity （WHC） and microstructure of its heat-induced gel. 【Method】 The α-helix of pork myofibrillar protein under different pH were measured by circular dichroism （CD）,and the hardness,WHC and microstructure of the heat-induced gel were determined by texture analyzer,centrifugation method and scanning electron microscope （SEM）,respectively. 【Result】 The α-helix of pork myofibrillar protein and WHC of its heat-induced gel increased with pH away from pI,the hardness reached its maximum when pH was 6.0,the gel had a uniform and orderly microstructure in neutral,while it had disorderly and uneven microstructure with polymer in the acidic. 【Conclusion】 The α-helix of myofibrillar protein is positive correlated with the WHC of its heat-induced gelation,and the gel has an orderly microstructure with more α-helix,while rough microstructure with less α-helix.