热加工过程中鲍鱼腹足蛋白间作用力及其质构特性

Chemical interactions and textural characteristics of abalone pleopod muscle protein during heating

为探究蛋白质形成凝胶过程中其化学作用力的变化规律以及与凝胶特性之间的关系,该文以鲍鱼腹足为原料,采用溶液分级提取方法,并结合扫描电镜和红外光谱法,考察热加工中鲍鱼腹足蛋白间作用力及其质构特性的变化情况。结果表明,随着加热温度升高(60、80、100℃),扫描电镜结果显示,鲍鱼腹足中间部位与边缘和过渡部位形成孔洞较小、排列紧密的网络结构,同时红外结果表明,随温度升高,蛋白二级结构发生明显变化,N-H弯曲和C-N伸缩振动较为明显,α-螺旋变为无规则卷曲结构,肌球蛋白疏水性增加,-S-S-形成。此时,对应离子键、氢键含量均呈下降趋势,疏水键相对含量呈先上升后下降趋势,二硫键、非二硫共价键含量呈上升趋势。进一步研究表明,各化学作用力与蛋白凝胶质构特性具有高度相关性。在较低温度下(60℃)离子键、氢键和疏水键对凝胶稳定性起主要作用,此时形成的凝胶较柔软;在较高温度下(80、100℃)二硫键、非二硫共价键为维持凝胶稳定的主要作用力,此时凝胶特性较佳,富有弹性、较好的凝聚性和回复性。该研究为热加工过程中鲍鱼腹足蛋白质变化的机理提供参考依据。

Abalone （Haliotis discus hannai） is an important commercial seafood species. Pleopod muscle is the edible part of abalone, which is rich in protein and mainly composed of myofibril protein and collagen. The change in conformation and aggregation of protein during heating would affect the quality of the product. Chemical interactions including hydrogen bonds, disulfide bonds, non-disulfide bonds, ionic bonds, and hydrophobicity have shown great effect on textural properties of muscle protein. This study used the method of grading extraction solution, scanning electronic microscopy （SEM）, and Fourier transform infrared （FTIR） to investigate the law of changes in chemical interactions and textural properties of the abalone （Haliotis discus hannai Ino） pleopod muscle protein. The results indicate that as the temperature increases （60℃, 80℃, 100℃）, the changes of chemical interaction in the center and the edge or transition part of the abalone muscle protein were similar. During heating, the content of ionic and hydrogen bonds declined; the content of hydrophobic bonds first increased and then decreased whereas disulfide and non-disulfide bonds increased but the increasing amount differed due to the different composition of protein. The center part is characterized by high amounts of myofibrilllar protein while the edge or transition part contains more collagen. The textural property shows the following change during low temperature （60℃）, the harness, resilience,springiness, cohesiveness, and chewiness of the abalone muscle were low. As the temperature increased, the parameters changed significantly. However, the harness and chewiness of the edge or transition part of the abalone muscle protein decreased slightly when temperature increased to 100℃.The results of SEM suggest that fresh abalone muscle exhibited a porous net structure composed of a vast amount of layers. However, as heating temperature increased （60℃, 80℃, 100℃）, a porous closed-knit structure with a tiny hole was formed both in the center and the edge or transition part of the abalone muscle. FTIR analysis indicates that the secondary structure of protein changed significantly; the N-H bond bended, C-N bond stretched and vibrated,α-helix showed non-regular curved structure, hydrophobicity of myofibrillar protein increased, and disulfide bonds were formed. In addition, there were close correlations between chemical interactions and textural characteristics, which indicate that ionic, hydrogen, and hydrophobic bonds played important roles in the soft gel during the low temperature （60℃） period. However disulfide and non-disulfide bonds were the main chemical interaction for the formation and maintenance of gel with excellent harness, springiness, and cohesiveness at the high temperature period （80℃, 100℃）. Our results not only expose the change of the secondary structure of the abalone muscle protein during the heating-gel forming process but also provide information on the relationship between chemical interactions and textural properties. The study provides useful information on the mechanism of protein changes in the pleopod muscle of abalone during heating and on the processing techniques of the abalone muscle.