Abstract: The zeta potential, particle size and infrared spectroscopic characteristics of 11S glycinin under different heat treatment conditions were investigated. The absolute value of zeta potential was reduced with increasing heat treatment time at 80 or 90 ℃, while it decreased at first and then increased at 100 ℃. The average particle size of 11S glycinin was increased at all three temperatures. The absolute value of zeta potential was changed more significantly and the average particle size was larger at 100 ℃. The changes in zeta potential and average particle size were related to the alteration in the molecular structure of the protein after heat treatment. For 2% 11S glycinin solution, the transformation of β-turn and random coil structure might offset each other during heat treatment at 80 ℃, and finally α-helix was transformed into β-sheet structure. Heat treatment at 90 ℃ for 30 min resulted in the transformation of α-helix and β-sheet into β-turn structure, and the secondary structures were no longer converted to each other after 30 min. In the first 20 min of heat treatment at 100 ℃, α-helix and β-sheet were rapidly transformed into β-turn and random coil structure, and the secondary structures were not converted to each other from 20 to 45 min of heat treatment. After 45 min, the transformation was further strengthened.

Key words: heat treatment, 11S glycinin, zeta potential, particle size, infrared spectroscopy