A Versatile Cryoprotection Strategy to Improve Frozen Quality of Food Gels Based on Solvent Displacement Strategy

In this work, a natural zwitterionic, betaine with varied dosages (4%, 6%, 8%, 10%, and 12%, w/v) was used to improve the freeze-thaw stability of frozen surimi gels. Specifically, Group 8B-S (8% betaine, w/v) increased gel strength and storage modulus of frozen surimi gels by 25.03% and 26.86% compared with the control group, respectively. Besides, the findings indicated that betaine also showed a versatile cryoprotection effect on frozen soy protein gels and agar gels, indicated by the relatively high gel strength. Differential scanning calorimetry (DSC) measurements showed that 8% betaine significantly reduced freezing point and freezable water content by 52.03% and 14.94% compared with the control group, respectively. Furthermore, the results of Raman spectroscopy and molecular dynamics simulations demonstrated that the ionic solvation effects of betaine disrupted the network, number, and lifetime of hydrogen bonds within water molecules, thereby improving ice recrystallization inhibition activity. This work establishes a theoretical framework for the creation of phosphorus-free antifreeze agents used in high-quality frozen food gels.