Effect of bovine hide gelatin antifreeze peptides on the quality of frozen dough treated with freeze-thaw cycles and its steamed bread

The structure of frozen dough was damaged due to the recrystallization of ice crystals during freeze-thawing. Therefore, the effect of bovine hide gelatin antifreeze peptides (BgAFPs) on the quality of frozen dough treated with freeze-thaw cycles and its steamed bread was investigated. The results showed that BgAFPs exhibited a high thermal hysteresis activity at 1.64 degrees C and possessed the significant ability to inhibit ice crystals growth due to its -Gly-X-Y- (where X was mostly proline or hydroxyproline, Y was any amino acid) repeating sequences. The decrease in gassing rate of frozen dough without BgAFPs (41.31%) was significantly greater than those of frozen dough with BgAFPs (36.32%, 27.74% and 24.30%), revealing that the BgAFPs had cryoprotective effect on yeast cells. Additionally, BgAFPs maintained a continuous apparent morphology of the frozen dough by inhibiting water migration. Specifically, the freezable water content in the frozen dough with 0% and 1.0% BgAFPs increased from 63.35% and 59.41% to 73.74% and 64.36%, respectively. Furthermore, BgAFPs increased the specific volume and springiness, decreased the hardness of the steamed bread. These results suggested that BgAFPs effectively attenuated the freeze-thaw induced damage to frozen dough and improved the quality of steamed bread.