冻融冻藏过程中κ-卡拉胶对面筋蛋白流变学特性及微观结构的影响

Effects of κ-Carrageenan on the Rheological Characteristics and Structure of Gluten during the Frozen-thaw Storage

利用流变仪、傅里叶变换红外光谱(FT-IR)、激光共聚显微镜(CLSM)探讨添加卡拉胶后对面筋蛋白在冻融过程中流变特性、和结构的影响。结果表明在冻融过程中,面筋蛋白的储能模量(G')、损耗模量(G')和二级结构随冻融时间的延长其变化分为三个阶段:从冻融开始到30 d为第一个阶段,面筋蛋白的G'、G'随着时间的延长明显下降,二级结构中1629 cm^(-1)处β折叠含量上升%,同时1656 cm^(-1)处α螺旋含量相对下降;冻融30 d到90 d为第二个阶段,面筋蛋白的流变特性和结构变化相对不太明显;冻融90 d到120 d为第三个阶段,G'、G'进一步下降,而1613 cm^(-1)处β折叠含量上升,对应的1656 cm^(-1)处α螺旋含量相应下降。CLSM显示冻融0 d时卡拉胶的分布主要集中在面筋蛋白网络结构的边缘,随着冻融时间的延长卡拉胶与面筋蛋白充分混合,形成蛋白多糖络合物增强面筋蛋白的凝胶特性,而当冻融时间达90 d后,面筋蛋白网络结构进一步破坏,出现了大量不规则的孔洞。

In this paper, the effects of k-carrageenan on the rheological properties, secondary structure and microscopic property of gluten during the frozen-thaw storage were studied by Rheometer, Fourier Transform Infrared Spectroscopy （FTIR） and Confocal Laser Scanning Microscope （CLSM）. The results showed that the changes of the storage modulus （G＇）, loss modulus （G＂） and the secondary structure of the gluten were divided into three stages during the frozen-thaw storage. The first stage was form 0 d to 30 d, where the G＇ and G＂ of the gluten decreased dramatically, and the content of fl-sheet （1629 crn1） increased significantly with decreasing the content of a-helix （1656 cm＂l） simultaneously. The second stage was form 30 d to 90 d, where the changes of rheometer parameters and secondary structure were not significant. During the third stage from 90 d to 120 d, the G＇ and G＂ of the gluten dropt again, while the content offl-sheet （ 1613 cm^-1） increased significantly with the decrease of a-helixcontent simultaneously （1656 cm^-l）. CLSM photographs showed that the distribution of carrageenan mainly concentrated on the edge of gluten network on the frozen-thaw 0 d, and then the carrageenan fully mixed with wheat gluten during the storage, which led to enhance gel properties of gluten. However, the gluten network structure was further damaged and a large number of irregular hole emerged up to 90 d.