Ice crystal recrystallization inhibition of type I antifreeze protein, type III antifreeze protein, and antifreeze glycoprotein: effects of AF(G)Ps concentration and heat treatment
Qingbao Ma, Mario Shibata, Tomoaki Hagiwara
Abstract
This study compared ice recrystallization behaviors of frozen dessert model systems containing type I antifreeze protein (AFP I), type III antifreeze protein (AFP III), and antifreeze glycoprotein (AFGP) at -10 °C. Specifically, effects of AF(G)P concentration and heat treatment (95 °C for 10 min) were examined. The concentration dependence of the ice recrystallization rate constant reasonably well fit a sigmoidal function: the fitting procedure was proposed, along with cooperative coefficient α, and a new index of AF(G)P ice recrystallization inhibition (IRI) activity (C50). After 95 °C heat treatment for 10 min, AFP III lost its ice crystal recrystallization inhibitory activity the most: AFP I was less affected; AFGP was almost entirely unaffected. These different thermal treatment effects might reflect a lower degree of protein aggregation because of hydrophobic interaction after heat treatment or might reflect the simplicity and flexibility of the higher order structures of AFP I and AFGP.