关键词: 米糠, 贮藏, 米糠球蛋白, 蛋白质氧化, 聚集体

Abstract: Rice bran globulin was prepared from defatted rice bran stored for different periods, and its structure was
investigated as a function of storage time of the starting raw material. The results showed that as the storage time increased,
the lipid in rice bran was gradually hydrolyzed and oxidized, and consequently protein carbonyl and disulfide contents of
rice bran globulin increased, along with a decrease in free sulphydryl content of rice bran globulin, which indicated that the
storage of rice bran could lead to the oxidation of rice bran globulin. As the storage time of rice bran was increased from day
0 to day 10, the intrinsic fluorescence intensity of rice bran globulin significantly declined, accompanied by blue shift of the
maximum emission wavelength. Meanwhile, the surface hydrophobicity gradually decreased, and the proportion and size of
protein aggregates in the molecular weight distribution of rice bran globulin increased, indicating that the storage of rice bran
could lead to the aggregation of rice bran globulin. The analysis of Fourier transform infrared spectroscopy indicated that the
contents of α-helix and β-sheet in rice bran globulin decreased, and the contents of β-turn and random-coil increased after
storage of rice bran. Electrophoresis indicated that protein oxidation could lead to the formation of oxidative aggregates of
rice bran globulin with the involvement of disulfide and a small amount of non-disulfide covalent bonds.

Key words: rice bran, storage, rice bran globulin, protein oxidation, aggregation