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 of α-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, the α-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. The α-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.