关键词: 大米, 谷蛋白, 碱处理, 结构, 性质

Abstract: The changes in the structure and properties of rice glutelin after alkali treatment were explored. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), automatic amino acid analyzer, differential scanning calorimetry (DSC), surface hydrophobicity analysis, scanning electron microscopy (SEM) and deamidization analysis were applied to elucidate the structure of rice glutelin, and solubility, emulsifying properties and foamability were determined to clarify the change of its properties. The results from SDS-PAGE and DSC showed that rice glutelin was denaturated completely, when the concentration of sodium hydride was 0.08 mol/L or higher, causing considerable degradation of subunits and the formation of macromolecular aggregates. When pH was 12.0 or higher, glutelin solubility increased significantly and reached 80% at pH 13.0. Alkali at high concentration above 0.1 mol/L caused deamidization, leading to a significant increase of glutamate content in the glutelin molecule, and the degree of deamidization was correlated with solubility and surface hydrophobicity. Results from SEM showed that alkali treatment led to the degradation and more loose structure of rice glutelin. Appropriate alkali treatment improved the emulsifying properties and foamability of rice glutelin, and the optimum condition was treatment of rice glutelin for 120 min with 0.5 mol/L NaOH solution, but excessive alkali treatment could destroy its emulsification properties and foamability. Proper alkali treatment changed the structure of rice glutelin and accordingly improved its solubility, emulsifying properties and foamability, which is expected to be effectively utilized in food or related fields.

Key words: rice, glutelin, alkali treatment, structure, properties