油酸与甘油对玉米醇溶蛋白膜机械性能的影响及机理探讨

Effect of oleic acid and glycerol on mechanical properties of zein film and its mechanism investigation

主要研究了两种性质不同的增塑剂(油酸和甘油)对玉米醇溶蛋白(zein)膜机械性能的影响和可能的机理,以抗拉伸强度(TS)、伸长率(E)、透水率(WVP)为指标,结果发现油酸和甘油都能显著改善zein膜的机械性能,且添加量都以20%(g/g zein)最优;复合增塑研究发现,当添加20%混合增塑液对zein膜进行增塑时,以油酸∶甘油为3∶1复合增塑的效果最好,其中与未增塑的zein膜相比,TS提高190%,E提高70%。进一步统计学分析表明,油酸与甘油在对zein膜增塑时有正协同作用。对未增塑、20%油酸增塑、20%甘油增塑及20%复合增塑(油酸∶甘油为3∶1)zein膜的玻璃态转化温度(Tg)及红外光谱(FT-IR)分析发现,增塑后的zein膜Tg有所下降,其中复合增塑降幅最大;FT-IR图谱分析发现,复合增塑时甘油的特征峰向高波长方向移动,显示增塑作用加强;蛋白二级结构分析发现,复合增塑后,二级结构虽有小幅改变,但并未达到显著水平,因此增塑剂与zein之间的非共价键相互作用(疏水力和氢键)可能是其增塑的化学基础。

The effect of two kinds of different nature plasticizer （oleic acid and glycerol） on zein membrane mechanical properties and possible mechanisms was studied according to the index of tensile strength, elongation,water permeability. It was found that oleic acid and glycerol could significantly improve the mechanical properties of zein films,and the optimal quantity was 20% （g/g zein）;compound plasticized study found that when added 20% mixed plasticizer into zein film,the best ratio of oleic acid and glycerol was 3：1 ,whose tensile strength had increased 190%,elongation had increased 70% compared to non-plasticized zein films. Further statistical analysis showed that oleic acid and glycerol had synergy in plasticized zein films. Glass transition temperature（Tg） and infrared spectroscopy（FT-IR） analysis found that the Tg of zein film decreased after plasticized,and the largest decline was found in the film which was plasticized by plasticized compound （oleic acid：glycerol=3：1）by FT-IR spectra analysis,it was found that when the zein film was plasticized by 20% plasticized compound,the characteristic peak of glycerol moved to higher wavelengths,which indicated plasticization had been strengthened. By secondary structure analysis of zein films,it was found that,although slight changes could be found in secondary structure after the zein film was plasticized by compound plasticizer,significant levels had not be reached,so,the chemical mechanism of the plastication of zein film was likely to be based on the non-covalent interactions （hydrophobic force and hydrogen bonding） between plasticizers and zein.