木糖接枝改性温度对花生蛋白膜物理性质的影响

Effect of Xylose's Grafting Temperature on the Physical Properties of Peanut Protein Film

为改善花生蛋白膜的性能,在不同温度（30~90℃）下利用木糖对花生蛋白进行接枝改性,将改性蛋白制备成膜,分析不同改性温度下花生蛋白膜的微观结构、颜色、耐水性（包括溶解性、膨胀性和表面疏水性）和机械性能（包括拉伸强度和断裂延伸率）,结果表明,随着改性温度的升高,蛋白膜内部逐渐形成网状结构,同时美拉德反应程度的加深使蛋白膜的颜色变暗,且耐水性和机械性能均有所增强,表现为溶解性和膨胀性下降,表面疏水性、拉伸强度和断裂延伸率提高。90℃改性所得花生蛋白膜的综合性能较好,其内部呈紧密的网状结构;溶解性和膨胀性最低,分别为33.64%和359.98%;强度和延伸性最强,分别达9.30 MPa和103.67%;其颜色较深,色差为15.43。高温有利于花生蛋白的糖接枝改性以及蛋白膜性能的提高。本结果为花生蛋白膜的进一步开发利用提供理论基础。

In order to improve the properties of peanut protein films, peanut protein isolate（PPI） extracted from peanut meal was modified by sugar grafting with xylose at different temperature. Peanut protein films made of the modified protein were prepared by casting. And the effects of modification temperature on the physical properties such as microstructure, color, water resistance, including water solubility, swelling properties and surface hydrophobicity, and mechanical properties including tensile strength（TS） and elongation at break（EB） have been studied. The results showed that, with increasing heating temperature, network structure was formed inside the protein film. Moreover, the degree of Maillard reaction between PPI and xylose increased with the increasing temperature, leading to darker color, improved water resistance and better mechanical properties of the films, including decreases in water solubility and swelling properties, and increases in surface hydrophobicity, tensile strength and elongation at break. When peanut protein was modified by sugar grafting with xylose at 90 ℃, the films exhibited superior properties. The cross sectional microstructure of the modified film showed a homogenous and more compact structure. Such films exhibited lowest solubility（33.64%） and swelling properties（359.98%） and highest tensile strength（9.30 MPa） and elongation at break（103.67%）, but showed a dark color with a color difference of 15.43. In conclusion, higher temperature is beneficial for sugar grafting modification of peanut protein and improving the properties of peanut protein films. The improvements of the peanut protein films raise the possibility of employing such innovative films as edible materials in food packaging industry. The results of this research provide the theoretical foundation for the properties improvement and further development of peanut protein film.