花生蛋白高水分挤压组织化过程中的化学键变化

 【目的】从挤压产品微观结构、化学键变化和蛋白质酰化改性等方面，探讨花生蛋白高水分挤压组织化结构的形成机理。【方法】采用扫描电子显微镜观察挤压产品的微观结构，利用物性测定仪分析挤压产品的质构特性，用化学分析方法对蛋白质中的总巯基和二硫键含量进行分析，采用琥珀酰化的方法对花生蛋白进行酰化处理。【结果】蛋白质溶解度试验结果显示，随挤压温度的升高，花生蛋白的溶解度迅速降低，在含2%SDS和2%SDS+2%2-ME缓冲液中的溶解度显著增加，最高达76.89%（140℃），说明挤压产品中以非共价键结合的蛋白质含量显著增加。随挤压温度的增加，二硫键含量在140～150℃范围内呈缓慢下降趋势，在155℃时显著降低。花生蛋白质酰化后，挤压产品的硬度、咀嚼度和组织化度等显著降低，相应的微观结构也显示出显著的变化。【结论】在花生蛋白高水分挤压组织化过程中，疏水作用和氢键起主要作用，其次是二硫键。在挤压过程中，花生蛋白分子内原有的二硫键含量降低，可能发生了部分断裂，高温会加速该反应的进行。酰化改性明显干扰了蛋白质分子间的相互作用，不利于挤压产品良好组织化结构的形成。

Changes of Chemical Bonds in Peanut Protein High Moisture Extrusion Texturization

Abstract: 【Objective】The effects of extrusion temperature on the microstructure of extrudates, protein solubility in 5 solvents, total sulphhydryl and disulfide bonds contents of extrudates were investigaged, and the effects of succinylated modification before extrusion on the structures and rheology properties of extrudates were also discussed in this paper, and aimed to grope for the mechanisms of peanut protein high moisture extrusion texturization. 【Method】The microstructures of extrudates observed by scanning electron microscope, the rheology properties of extrudates analysed by texture profile analyzer, and the conventional chemical methods were used to determined the total sulphhydryl and disulfide bonds contents of extrudates and succinylation of peanut protein. 【Result】(1) The solubility of peanut protein was greatly decreased with extrusion temperature increasing, but the protein solubility obviously increased when buffer contained sodium dodecyl sulphate (SDS), alone or combination with 2-mercaptoethanol (2-ME); The changes of total sulphhydryl contents among extrudates were not significant, disulphide contents of extrudates slightly decreased at 140-150℃, and decreased significantly at 155℃. (2)The hardness, chewiness and texturized degrees of extrudates were significantly decreased with peanut protein succinylated modification before extrusion. The microstructure of extrudates identified the changes of the rheology properties.【Conclusion】(1) Hydrophobic interactions and hydrogen bonds played the main function, and disulphide bonds was the second during peanut protein texturization. (2) Disulfide bonds in peanut protein molecules were cleaved during extrusion, and the higher temperature could accelerate this reaction. (3) Succinylated modification could disturbed the interactions between protein molecules and hindered the fibrous structure formation during extrusion texturization.