Freezing and Ice Recrystallization Properties of Sucrose Solutions Containing Ice Structuring Proteins from Cold-Acclimated Winter Wheat Grass Extract

Abstract

The freezing properties of sucrose solutions containing ice structuring proteins (ISPs) from cold-acclimated winter wheat grass extract (AWWE) were evaluated. Neither significant ice nucleation nor thermal hysteresis activity in unpurified AWWE were detected (P > 0.05). Ice recrystallization in sucrose solutions was assessed by bright field microscopy. Ice crystal growth was significantly reduced with the addition of more than 0.05% total protein from AWWE in 23% sucrose solutions frozen under static conditions and temperature cycled under long periods of time (60 min). Ice recrystallization inhibition was not evident when the samples were temperature cycled for shorter periods of time (10 min), indicating that an adsorption time may be required for the ISPs to be significantly active. The ice recrystallization was reduced with the increased on ISP concentration until reaching a plateau after adding 0.13% total protein from AWWE, representing a surface coverage of 9 mg protein/m2 ice (assuming 100% adsorption). The reduction of ice crystal growth was as high as 74% compared with the control. This ice recrystallization inhibition offers significant opportunity for the use of ISPs from AWWE in frozen foods.