冻融冻藏中卡拉胶对面筋蛋白分子量及超微结构的影响

Effects of carrageenan on the molecular weight and microstructure of gluten during freeze- thaw cycles storage

实验采用空间排阻色谱和多角度激发光光散射联用（SEC-MALLS）、聚丙烯酰胺凝胶电泳（SDS-PAGE）以及扫描电镜（SEM）研究面筋蛋白在冻融冻藏（以10 d作为一个冻融周期,在每个冻融周期的第5 d,将冷冻在-18℃的样品升温至0℃,并在此温度下保持12 h后降温至-18℃继续冻藏）中添加卡拉胶对面筋蛋白分子量及其分布、蛋白质亚基、自由巯基含量及超微结构的影响。结果表明,随着冻融时间的延长,面筋蛋白的分子量下降,主要集中在105-106u,添加卡拉胶明显减缓了分子量下降。冻融过程中,面筋蛋白亚基没有发生变化,自由巯基含量增加,相同时间下添加卡拉胶组面筋蛋白的自由巯基含量低于空白组,冻融120 d后空白组为4.89μmol/g而卡拉胶添加组为4.13μmol/g。通过SEM观察超微结构,冻融过程中空白组面筋蛋白网络结构明显弱化,冻融120 d后有直径50μm的孔洞出现,而卡拉胶添加组孔洞大小相对均一。说明添加卡拉胶能有效减缓冰晶对面筋蛋白的破坏,抑制面筋蛋白解聚作用。

In this paper,the effects of freeze- thaw cycles（ frozen at- 18 ℃ with cycling to 0 ℃ for 12 h and then back to- 18 ℃ per 10 days） on molecular weight and distribution,protein subunits,free sulfhydryl group and microscopic property of gluten with carrageenan were studied by the multiangle laser light scattering（ MALLS） in combination with size exclusion chromatography（ SEC）,sodium dodecyl sulfate- polyacrylamide gel electrophoresis（ SDS- PAGE） and scanning electron microscopy（ SEM）.The results showed that during the freeze- thaw cycles,the molecular weight of the gluten was significantly decreased,especially in 105- 106 u,while the molecular weight of the gluten added carrageenan descreased slightly contrast with the control. The SDS- PAGE profiles revealed that there were no remarkable difference and relative mobilities of band for the gluten protein subunits.The free sulphydryl group content increased during the storage,the 4.89 μmol / g for control compared with4.13 μmol / g for the gluten added carrageenan stored for 120 days,which implying the carrageenan can offer protection to the disulfide bonds.SEM photographs showed that the network was weakened with increasing freeze- thaw cycles storage time,the pore size of the control sample was increased to 50 μm after stored for 120 days,while the gluten added carrageenan was highly uniform in size. These results indicated that the addition of carrageenan could reduce the depolymerisation caused by recrystallization and protect the structure of gluten.