Abstract:

The changes in structure and functional properties of rice bran protein caused by dry heat treatment were studied
in this research. Results showed that dry heat treatment at 90 ℃ caused obvious denaturation of rice bran protein, which
was manifested by a considerable decrease in β-sheet content and consequently an increase in random coil and β-turn
contents. The α-helix content increased gradually with an increase in heating temperature, while random coil structure and
β-sheet structure did not exhibit an obvious linear trend. The dry heat treatment resulted in the formation of more disordered
structures and promoted the hydration of rice bran protein, in turn improving its solubility. However, rice bran protein
became less soluble after undergoing dry heat treatment at 100 ℃. The overall flexibility of rice bran protein was enhanced
due to the formation of more disordered structures, and the emulsifying activity tended to decrease and then increase with
increasing temperature. Maximum emulsifying activity index (EAI) of 45.56 m2/g was obtained by dry heat treatment at
100 ℃, accompanied with an increase in emulsion stability. The foaming capacity of rice bran protein displayed an upward
and then downward trend with increasing temperature. Heat treatment at 80 ℃ gave maximum foam overrun of 87.36%, and
the foam stability was decreased by increasing temperature.

Key words: dry heat treatment, rice bran protein, protein structure, functional properties