Effect of freeze–thaw cycles on the molecular weight and size distribution of gluten
Effect of freeze–thaw cycles on the molecular weight and size distribution of gluten
复制标题
DOI：
10.1016/j.foodres.2013.04.013
复制
发表时间：
2013-08
影响因子：
8.1
通讯作者：
Lei Zhao;Lin Li;Guoqin Liu;Ling Chen;Xingxun Liu;Jie Zhu;Bing Li
中科院分区：
文献类型：
--
作者：
Lei Zhao;Lin Li;Guoqin Liu;Ling Chen;Xingxun Liu;Jie Zhu;Bing Li
冷冻加工在食品工业中得到了广泛的应用，但一些关键的科学问题仍不清楚。采用体积排阻色谱结合多角度激光光散射(SEC-MALLS)、分光光度法和原子力显微镜(AFM)研究了冻融循环对面筋蛋白的相对分子质量、转动半径、游离氨基含量、游离基含量和分子构象的影响。结果表明，在冻融循环中(在−-18℃下冷冻，每10天循环到0℃12小时，然后回到−-18℃)，面筋蛋白的相对分子质量和回转半径随着冻融循环的增加而减小，这意味着面筋蛋白的高相对分子质量部分发生了解聚。面筋中游离氨基含量变化不大，面筋中游离硫基的含量从对照的9.8kgMol/g增加到12次冻融循环的13.87nμμ/g，说明面筋在冻融循环过程中的解聚是由于二硫键断裂所致。AFM图像显示，面筋蛋白链形成了纤维状的支链网络，随着冻融循环储存时间的增加，这种支化网络逐渐减弱。在AFM图像中也观察到面筋素链的聚集。
Freezing processing is widely used in food industry, but some key scientific issue is still unclear. In this paper, the effects of freeze–thaw cycles on the molecular weight, radius of gyration, free amino group content, free sulphydryl group content and molecular conformation of gluten were investigated by size-exclusion chromatography in conjunction with multi-angle laser light scattering (SEC–MALLS), spectrophotometry and atomic force microscopy (AFM). The results showed that during the freeze–thaw cycles (frozen at − 18 °C with cycling to 0 °C for 12 h and then back to − 18 °C per 10 days) the molecular weight and radius of gyration of the gluten proteins decreased with the increase in freeze–thaw cycles, implying a depolymerisation in the high-molecular-weight fraction of the gluten. The free amino group content changed only slightly, and the free sulphydryl group content of the gluten increased from 9.8 μmol/g for the control to 13.87 μmol/g for the gluten stored for 120 days and submitted to 12 times freeze–thaw cycling, indicating that the depolymerisation of the gluten during freeze–thaw cycling was due to the breakage of disulphide bonds. AFM images showed that the gluten chain formed a fibril-like branched network which was weakened with increasing freeze–thaw cycles storage time. Some aggregation of the gluten chains was also observed in the AFM images.