大米谷蛋白储藏过程中结构与功能性质变化的研究

为了研究大米储藏过程中谷蛋白结构与功能性质变化及其相关性，将大米在40℃、相对湿度80%的环境中模拟储藏11周，提取不同储藏时间下的谷蛋白，测定二级结构、内源荧光和功能性质的变化。结果表明，储藏的前5周谷蛋白结构展开，表现为α-螺旋含量从17.04%±3.89%降低至13.02%±0.94%，无规则蜷曲从19.40%±3.02%增加至29.04%±0.55%，同时谷蛋白的溶解性、持油性也相应增强；表面疏水性提升了325.73%，从而谷蛋白的乳化性和乳化稳定性、起泡性和起泡稳定性也随之增强，但持水性降低。而随着储藏时间的延长，在6~11周，谷蛋白α-螺旋含量升高，无规则蜷曲降低，内源荧光强度下降，同时蛋白的功能性质也随之下降，但乳化性有所增强。α-螺旋结构与功能性质变化存在显著相关性（P<0.01）。大米储藏过程中谷蛋白的结构变化与功能性质紧密相关。

Changes of Structure and Functional Properties of Glutelin during Rice Storage

We aimed to study the relationship between the structure and functional properties of glutelin of japonica rice during storage.The newly harvested rice was stored at 40℃and a relative humidity of 80%to accelerate the storage process,and glutelin was extracted at different storage times.FTIR(Fourier Transform Infrared)Spectrometer and CD(Circular Dichroism)were used to measure the secondary structure of glutelin.Fluorescence spectroscopy was used to determine the changes in the endogenous fluorescence and hydrophobicity of glutelin.At the same time,functional properties of glutelin were determined.The results showed that,during first 5 weeks of storage,the structure of glutelin was unfolded.The contents ofα-helix decreased from 17.04%±3.89%to 13.02%±0.94%,and random coil increased from 19.40%±3.02%to 29.04%±0.55%.Meanwhile,the solubility and oil-holding capacity of glutelin were enhanced.The surface hydrophobicity was also increased by 325.73%,which led to the increase in emulsification and emulsification stability,foaming and foaming stability of glutelin.However,the water holding capacity was reduced.With the extension of storage,theα-helix content of glutelin increases,but the random coil decreased.Meanwhile the intensity of endogenous fluorescence decreased in 6~11 weeks.The functional properties of glutelin showed a downward trend except for emulsification.Theα-helix structure was significantly related to the functional properties(P<0.01).The structural changes of glutelin were closely related to the functional properties during the storage of rice.