微波致米蛋白的自由基生成及氧化特性研究

The Radical Production and Oxidative Properties of Rice Protein under Microwave Radiatio

摘要:

本文研究了大米蛋白在微波场中自由基生成及氧化特性之间的关系。以电子自旋共振（ESR）为检测手段，对微波处理大米蛋白产生的自由基进行研究，验证了大米蛋白在微波处理后产生以碳为中心的自由基。对比实验结果可知，自由基不仅在微波加热后产生，原样本身也存在少量自由基。在微波场中，自由基信号随着水分活度的降低和微波功率的增加而逐渐增大。随处理时间延长，自由基信号强度增加，且增长速率递增。通过测定羰基、巯基、游离氨基及表面疏水性等蛋白氧化指标发现，微波处理过程中蛋白受热分解，内部疏水侧链暴露且部分肽链断裂，结合微波加热过程自由基的生成情况，可推测微波加热至80 ℃以上，以C为中心自由基的增长速率显著上升，且与氧化特性变化结果相符。

Abstract:

The relationship between radical production and oxidative properties of rice protein under microwave irradiation was investigated. Electron spin resonance (ESR) studies proved that the radicals produced in the microwaved rice protein samples were carbon-centered. Comparative studies revealed that radicals were not only produced in thermally treated materials, but also in small quantities in native samples of rice protein. Under microwave irradiation, the ESR signals for radicals gradually increased with the reduction of water activity as well as with the increase of microwave power. With the increase of irradiation time, the intensities increased, and the rate of increase of intensities of radical signals also increased. By measuring the surface hydrophobicity and the contents of carbonyl, sulfhydryl, and free amino groups, it was found that the internal hydrophobic side-chains of the protein were exposed and some of the peptide bonds were broken. Combined with the production of radicals during microwave irradiation, it was proposed that when microwaved to over 80 °C, the increase rate of production of carbon-centered radicals would be significantly higher, and was consistent with oxidation characteristics.