恒温冻藏对面筋蛋白结构及热力学特性的影响

恒温冻藏对面筋蛋白结构及热力学特性的影响

赵雷1，于亚楠1，胡卓炎1，李冰2,3，李琳2,3

（1.华南农业大学食品学院，广东广州 510642）（2.华南理工大学轻工与食品学院，广东广州 510640）

（3.广东省天然产物绿色加工与产品安全重点实验室，广东广州 510640）

摘要：本研究采用凝胶渗透色谱与光散射连用仪（SEC-MALLS ）、扫描电子显微镜（SEM ）和热重分析器（TGA ）探讨了恒温冻藏（-18 ℃）过程中对小麦面筋蛋白分子量及其分布、微观结构与热力学特性的影响。实验发现，随着冻藏时间的增加，由于二硫键的断裂，自由巯基含量增加，面筋蛋白发生了解聚现象，产生了小分子量的蛋白质。分子量较高的面筋蛋白（分子量范围：106 u~4×108 u ），在冻藏120 d 后分子量下降，而分子量较低的面筋蛋白（分子量范围：105 u~106 u ），在冻藏60 d 后分子量就开始发生了明显的下降。冻藏后面筋蛋白的网络状结构明显疏松，冻藏120 d 后有直径超过100 μm 的孔洞的出现，且分布不均一。热分析结果表明，面筋蛋白与麦谷蛋白的裂解温度都随着冻藏时间的增加而呈现下降的趋势，热稳定性下降。说明，冻藏过程中在水分的迁移和重结晶的作用下导致面筋蛋白高聚物发生了解聚现象，造成了面筋蛋白分子间二硫键的断裂，从而使得其网络结构疏松，面筋蛋白与麦谷蛋白热稳定性下降。

关键词：冻藏；面筋蛋白；分子量及其分布；微观结构；热力学特性

文章篇号：1673-9078(2016)5-161-166 DOI: 10.13982/j.mfst.1673-9078.2016.5.025

Effect of the Duration of Frozen Storage on the Structure and

Thermodynamic Properties of Gluten Protein

ZHAO Lei 1, YU Y a-nan 1, HU Zhuo-yan 1, LI Bing 2,3, LI Lin 2,3

(1.College of Food Science, South China Agricultural University, Guangzhou 510642, China) (2.College of Light Industry and Food Sciences, South China University of Technology, Guangzhou 510640, China) (3.Guangdong Province Key

Laboratory for Green Processing of Natural Products and Product, Guangzhou 510640, China)

Abstract: The effects of frozen storage (-18 ℃) on the molecular weight, the distribution of molecular weight, microstructure and thermodynamic properties of wheat gluten protein were studied by size-exclusion chromatography in conjunction with multi-angle laser light scattering (SEC-MALLS), scanning electron microscope (SEM) and thermogravimetric analyzer (TGA). With increasing storage time, free thiol content increased due to the cleavage of disulfide bonds. Depolymerisation of the gluten proteins occurred, and low molecular weight proteins were produced. The molecular weight of the gluten proteins with relatively high molecular weight (106 u ~ 4 × 108 u) was decreased after 120 days of storage, and that of the relatively low molecular weight (105 u ~ 106 u) gluten proteins exhibited a significant decline after 60 days of storage. The mesh like structure of gluten proteins became significantly loose, and unevenly distributed pores with a diameter over 100 μm could be seen after 120 days of storage. Thermal analysis indicated that the degradation temperatures of the gluten and glutenin showed a downward trend with increasing storage time and their thermal stability decreased. To summarize, during frozen storage, moisture migration and recrystallization led to the depolymerization of the gluten polymers, and the disulfide bonds between gluten protein molecules were broken, so that the mesh like structure became loose and the thermal stability of the gluten and glutenin decreased.

Key words: frozen storage; gluten protein; molecular weight and its distribution; microstructure; thermodynamic properties;

目前，在食品行业中，冷冻面制品以其安全、方便并保持食品本身营养价值等优点而得到了迅速发

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收稿日期：2015-10-15

基金项目：国家自然科学基金资助项目（31301412、31130042）；国家科技支撑计划（2012BAD37B01）；广东省自然科学基金资助项目（S2013040014403） 作者简介：赵雷（1982-），男，博士，副教授，研究方向：天然高分子改性 通讯作者：李琳（1962-），男，博士，教授，研究方向：食品与生物化工

展。冷冻面制品的质量很大程度上取决于冷冻面团的

品质[1]。研究表明，构成面团的主要成分面筋蛋白的特性影响着面团的品质。面筋蛋白是自然界中发现的

分子量最大的蛋白质[2]，由醇溶蛋白（gliadin ）

和麦谷蛋白（glutenin ）组成。由这两种蛋白质所形成的面筋蛋白网络结构使面制品具有粘弹性，大分子的谷蛋白聚合物赋予面筋蛋白弹性性能，而单体的醇溶蛋白赋