γ-聚谷氨酸对冻藏谷蛋白水合及结构的影响

Effect of γ-Polyglutamic Acid on Hydration and Structure of Frozen Glutenin

为有效抑制冻藏期间谷蛋白的劣变,采用核磁共振成像仪、傅里叶红外仪、差示扫描量热仪、动态流变仪和扫描电子显微镜等研究冻藏期间γ-聚谷氨酸对谷蛋白水合及结构的影响。结果表明:添加γ-聚谷氨酸能有效提高谷蛋白保水能力,使谷蛋白中2%的自由水含量转化为弱结合水,并显著改善冻藏引发的谷蛋白水分迁移。同时抑制谷蛋白二级结构中β-折叠含量的降低及无规则卷曲含量的升高。热力学结果表明:γ-聚谷氨酸使冻藏7周的谷蛋白变性温度提升4℃,减弱了冻藏期间热焓值的降低,并明显改善谷蛋白冻藏期间弹性性能的下降趋势。冻藏期间添加γ-聚谷氨酸的谷蛋白网络破坏较小,比未添加γ-聚谷氨酸的谷蛋白有更多的交联,体现出更为完整的网络结构。

In order to inhibit effectively the deterioration of glutenin during freezing.The effects ofγ-polyglutamic acid on hydration and structure of glutenin during frozen storage were studied by magnetic resonance imaging,Fourier infrared,differential scanning calorimetry,dynamic rheometer and scanning electron microscopy.The results showed that the addition ofγ-polyglutamic acid can effectively improve the water retention capacity of glutenin,and convert 2%free water content of glutenin into weakly bound water,and significantly improve the moisture migration of glutenin induced by frozen storage.At the same time,the decrease ofβ-sheet content and the increase of random curl content in the secondary structure of glutenin were inhibited.The thermodynamic results showed thatγ-polyglutamic acid increased the denaturation temperature of glutenin during 7 weeks of freezing to 4℃,which reduced the decrease of thermal enthalpy during the freezing period and significantly improved the decline of elastic properties during glutenin freezing.The glutenin network withγ-polyglutamic acid added has less damage to the space network during its frozen storage,and it shows a more complete network than without adding more cross-linking.