米糠贮藏不同时间脱脂制备米糠蛋白，研究米糠贮藏时间对米糠蛋白结构的影响。结果表明：随着米糠贮藏时间的延长，米糠脂质逐渐水解和氧化，米糠蛋白羰基和二硫键含量分别从1.76和5.69 nmol/mg增加到9.16和8.25 nmol/mg，游离巯基含量从7.58下降到1.22 nmol/mg，表明米糠贮藏期间米糠蛋白发生了氧化。当米糠贮藏时间由0 d增加到10 d，米糠蛋白内源荧光强度下降，最大荧光峰位蓝移，表面疏水性下降，米糠蛋白分子量分布图中蛋白质聚集体比例和粒径增加，表明米糠贮藏期间米糠蛋白逐渐形成氧化聚集体；傅里叶红外分析表明蛋白质氧化导致米糠蛋白α-螺旋和β-折叠含量下降，β-转角和无规卷曲含量上升。电泳分析表明，蛋白质氧化导致米糠蛋白形成了氧化聚集体，二硫键和非二硫共价键参与了氧化聚集体的形成。表明米糠酸败可诱导米糠蛋白氧化，导致米糠蛋白结构改变和形成氧化聚集体。

Rice bran stored for different periods before defatting and preparing rice bran protein were used to analyze the effect of storage time on the structure of rice bran proteins. The results showed that, as storage time increased, rice bran lipids were gradually hydrolyzed and oxidized. The protein carbonyl and disulfide content of rice bran protein increased from 1.76 and 5.69 nmol/mg and 9.16 and 8.25 nmol/mg, respectively, while free sulfhydryl content decreased from 7.58 to 1.22 nmol/mg, which indicated that storage of rice bran caused oxidation of the rice bran proteins. As storage time of rice bran increased from zero to ten days, a decrease in the intrinsic fluorescence intensity of rice bran protein was accompanied by a blue shift of the wavelength of maximum emission. A gradual decrease in surface hydrophobicity and an increase in the ratio of protein aggregates in molecular weight distribution profiles of rice bran proteins were also observed, which indicated that storage of rice bran led to the aggregation of rice bran proteins. Fourier transform infrared spectroscopic analysis indicated that the α-helix and β-sheet content decreased, while the β-turn and random-coil content increased during storage. The results of electrophoresis also indicated that protein oxidation led to the formation of oxidative aggregates of rice bran proteins, and that disulfide as well as non-disulfide covalent bonds participated in the formation of these aggregates. The results of this study indicated that the rancidity-induced oxidation of rice bran proteins changed their structure and caused the formation of oxidative aggregates.

公益性行业（农业）科研专项(201303071)；湖南省教育厅项目（14C1181）