挂面在常温储藏过程中品质及麦谷蛋白化学特性的变化

Changes of the quality of noodles and the chemical properties of glutenin in Chinese dried noodles stored at room temperature

为了研究挂面在常温储藏过程中麦谷蛋白化学特性的变化及对面条品质的影响,对两种不同筋力的小麦制作的挂面进行常温储藏并提取麦谷蛋白,对比挂面的品质指标和麦谷蛋白的巯基、二硫键、麦谷蛋白大聚体(GMP)、二级结构以及高分子量亚基(HMW-GS)的变化。结果表明:两种挂面的L∗随着储藏时间的延长均逐渐下降,b∗呈现升高趋势;两种挂面的微观结构随着储存时间的延长均变得越来越松散,面筋蛋白网络的连续性被破坏,导致硬度、弹性等指标和感官评分下降;随着挂面储藏时间的延长,二硫键含量呈现下降趋势,GMP逐渐降解,二级结构的含量变化显著,蛋白质分子的蛋白构象变得混乱,十二烷基酰胺凝胶电泳图显示HMW-GS逐渐发生解聚,面团韧性下降,挂面品质发生劣变从而影响食用品质。综上,挂面在常温储藏过程中麦谷蛋白化学组分的变化与面条食用品质的下降存在一定的相关性。

In order to study the changes of chemical properties for glutenin in Chinese dried noodles stored at room temperature and its effect on the quality of noodles,noodles made from two kinds of wheat with different gluten were stored at room temperature.After the extraction of glutenin,the quality of noodles and sulfhydryl groups(SH),disulphide bonds(SS),glutenin macropolymer(GMP),secondary structures and high molecular weight glutenin subunit(HMW-GS)were determined and analyzed in the study.The results showed that the L∗value of two kinds of Chinese dried noodles decreased gradually with the increase of storage time,which was closely related to the decrease of moisture content in noodles during storage,while b∗value tended to increase,indicating that the brightness of noodles after storage reduced significantly(P<0.05),and Chinese dried noodles gradually became dark and yellow.By SEM characterization,the microstructures of noodles became looser,the continuity of gluten protein network was destroyed and most of the starch granule was exposed,leading to the decrease of hardness,springiness,firmness,breaking force and sensory score,as well as an increasing adhesiveness of Chinese dried noodles.Moreover,with the increase of storage time,GMP was degraded gradually and the quality of protein was reduced because of a lower SS content,which affected the edible quality of flour products.The secondary structures of glutenin was altered remarkably and the protein conformation became chaotic,resulting in the destruction of the protein network structure and the decrease of the quality of cooked noodles.Sodium dodecyl sulfate-polyac-rylamide gel electrophoresis(SDS-PAGE)results revealed that the number of glutenin bands in two kinds of Chinese dried noodles decreased and the color became undertint gradually,and the change was most obvious especially when the storage time reached 180 days,which indicated that HMW-GS was depolymer-ized obviously,leading to the decrease of dough toughness and the quality deterioration of Chinese dried noodles.In summary,changes of chemical properties for glutenin in Chinese dried noodles stored at room temperature were relevant to the poor textural properties and edible quality of Chinese dried noodles to a certain extent,which provided a theoretical basis for the subsequent discussion on the factors influencing the quality of Chinese dried noodles,and also laid a foundation to study the change of glutenin stored at room temperature.