Initial ice growth control mechanism for CMC-Na in model systems

In this study, CMC-Na solutions with different DS and concentrations were frozen at −20 °C and −40 °C. At the macroscopic level, the nucleation temperature and nucleation start time were analysed by freezing curves, and the morphology, size, and quantity of ice crystals after recrystallization were captured dynamically at the microlevel. The results show that CMC-Na can effectively accelerate the nucleation process, shorten the phase transition time, and evenly promote the formation of numerous distributed small ice crystals, and there is no significant difference in the effect of CMC-Na at different freezing temperatures. At the microlevel, a high concentration of CMC-Na can inhibit the recrystallization process more effectively, probably because it is readily attached to the surface of ice crystals, and the reduction in surface tension increases the free energy, which prevents the growth of ice crystals. When CMC-Na is added to the ice cream system, it can reduce the nucleation temperature, increase the degree of supercooling, and promote the internal generation of abundant ice crystals. At the same annealing rate, CMC-Na can effectively inhibit the occurrence of recrystallization, which is consistent with the conclusion of the solution system.