Cryoprotective effects of silver carp muscle hydrolysate on frozen dough subjected to multiple freeze-thaw cycles and their underlying mechanisms

This study was aimed to investigate the cryoprotective effects of silver carp muscle hydrolysate (SCMH, 14% degree of hydrolysis) on frozen dough subjected to 0-6 freeze-thaw cycles, using trehalose as a reference. The results showed that the addition of SCMH in dough led to significant increase (p < 0.05) of the survival rates (79-93%) and relative fermentation capacity (59-95%) of yeast in dough subjected to 2-6 freeze-thaw cycles as compared to the control (survival rates: 43-59%; relative fermentation capacity: 29-58%) and trehalose (survival rates: 61-71%; relative fermentation capacity: 48-73%) treated counterparts. The presence of SCMH in dough also led to an increase in the specific volume of the resulting bread as well as decreases in the hardness, adhesiveness, and chewiness of bread, indicating that SCMH has a good cryoprotective effect on frozen dough. Further analysis found that the freezable water content of frozen dough with SCMH increased by only 5% after 6 freeze-thaw cycles, significantly less (p < 0.05) than the control (increased by 11%) and trehalose treated dough (increased by 9%). Accordingly, frozen dough that included SCMH showed less starch granule deformation and a more complete gluten structure, while the resulting bread was characterized by larger gas-cell density and smaller average cell area. These findings could be interpreted as the consequences of reduced formation and recrystallization of ice crystals due to decreased freezable water content, as well as the subsequent reduction in freeze-damage to the frozen dough.

Automated summary

The study found that the addition of SCMH to frozen dough significantly improved yeast survival rates and fermentation capacity, resulting in bread with increased specific volume and reduced hardness. SCMH also led to a lower increase in freezable water content after freeze-thaw cycles compared to control and trehalose treated dough, indicating its role in reducing freeze-damage and maintaining gluten structure.