NaCl对猪肉肌原纤维蛋白乳化体系加工特性的影响

Effect of NaCl on processing properties of pork myofibrillar protein emulsion

研究NaCl浓度对肌原纤维蛋白乳化体系流变特性和保水性的影响。以猪肉肌原纤维蛋白为研究对象,采用流变仪、低场核磁共振分析仪分别测定了用含0.2、0.4和0.6 mol·L-1NaCl的磷酸盐缓冲液配制的猪肉肌原纤维蛋白溶液及其乳化物的流变特性、水分的移动性及分布规律,并观察凝胶微观结构的变化。结果表明:0.6 mol·L-1NaCl肌原纤维蛋白溶液及乳化物的储能模量(G')和损失模量(G″)最大,而0.2 mol·L-1NaCl时G'和G″变化不大,未形成稳定的凝胶网络结构;与0.4和0.6 mol·L-1NaCl相比,低浓度NaCl肌原纤维蛋白乳化物及乳化凝胶的弛豫时间T21和T22明显下降,峰面积下降,而T23峰面积增加;0.6 mol·L-1NaCl肌原纤维蛋白及乳化凝胶结构呈规则有序的三维立体网络,结构更加致密、均匀,其乳化凝胶中油滴的界面蛋白膜光滑、完整,而0.2 mol·L-1NaCl的热诱导凝胶出现很多片状蛋白,凝胶空隙大,油滴界面蛋白膜出现明显破裂,凝胶结构不稳定。结论:随着NaCl浓度的增加,肌原纤维蛋白溶液及其乳化物的凝胶形成能力显著增强;低盐时,水的移动性降低,不易流动水向自由水转移,导致肌原纤维蛋白乳化凝胶汁液流失严重,保水性下降。

The objective of this study was to evaluate the effect of NaCl concentration on rheological properties and water holding capacity of myofibrillar protein emulsion. Myofibrillar proteins were extracted from pork and NaCl was added at 0. 2,0. 4 and 0. 6 mol·L^-1followed by mixing. Rheological properties,water mobility,distribution characteristics and microstructure of the mixture were analyzed.The results showed that 0. 6 mol·L^-1NaCl myofibrillar protein and its emulsion had the greatest storage modulus（ G＇） and loss modulus（ G″）,but G＇ and G″ changed little at 0.2 mol·L^-1NaCl and the stable gel network structure was not formed. Compared to the mixture at 0. 4 and 0. 6 mol·L^-1NaCl,the T21 and T22of myofibrillar protein emulsion and its gel decreased greatly,and its peak area decreased as well,while peak area of T23 increased at 0. 2 mol·L^-1NaCl. The myofibrillar proteins and its emulsion gel at 0. 6 mol·L^-1NaCl had orderly,uniform and compact three-dimensional network,and the interface of protein membrane was smooth and complete,whereas the heat induced gel at 0. 2 mol·L^-1NaCl had a lot of flake protein and big pore,and the interface of protein membrane was ruptured,and as a result,gel structure was unstable. Conclusions： The ability to form emulsion gel became stronger with NaCl concentration increasing. At low salt,the water mobility decreased and the immobilized water went out to be free moisture,resulting in a serious juice loss and the decrease of water-holding capacity.