Cryo-protective effect of ice-binding peptides derived from collagen hydrolysates on the frozen dough and its ice-binding mechanisms

Ice-bonding collagen peptides (IBCPs) from bovine bone collagen hydrolysates were isolated by an improved iceaffinity adsorption system. Then its breadmaking performance in the frozen dough and ice-binding mechanism were investigated. The results showed that the isolation time of IBCPs was shortened to 6 h using the improved ice-affinity adsorption system. IBCPs with the molecular mass distribution of 3000-5000 Da exhibited the highest thermal hysteresis (TH) activity (5.77 degrees C), which can be classified as hyperactive. When the IBCPs of 0.25% was added in the frozen dough, the distribution of water molecules was significantly changed with a decrease in freezing time (43.93%) and thawing time (37.25%). The addition of IBCPs also considerably increased the survival rate of yeast and thereby improved the texture of the steamed bread. Further study showed that the crystals grew in the IBCPs solution perpendicularly to the c axis of the crystal with a low crystals growth rate (k value of 149.50 mu m(2) S-1), and then produced unusual six-pointed-star shapes. Moreover, the binding of oxygen triad plane of IBCPs to the primary and secondary prism faces of ice appears to be the mechanism by which IBCPs inhibited ice crystal growth.