Effect of anti-freeze agents on ice crystal size and physical properties of model frozen desserts

Replacing sugar in frozen desserts is a strategy to reduce sugar content, but the role of different anti-freeze agents in the structural development and properties is not yet fully understood. In our study, we examined how sucrose, glucose, xylitol, and ethanol affected ice crystal formation in a simplified frozen dessert system. Through microscopy analysis, we found that anti-freeze agents with small molecular weight resulted in significantly larger ice crystals. In contrast, smaller ice crystals were formed when ice content was reduced. Due to differences in molecular weight, the lower-molecular-weight agents also decreased serum phase viscosity. To be able to distinguish the individual effects of ice crystal size and viscosity on hardness and melting behaviour, frozen dessert systems with constant serum phase viscosity and varying ice crystal radius were prepared. Samples with smaller ice crystals were harder and showed a higher storage modulus due to higher ice crystal connectivity. By testing the core temperature of melting samples, we confirmed that small ice crystals delayed the heat transfer process during melting, and thus melted more slowly. Melting rate was not influenced by serum phase viscosity, indicating that the melting was mostly dominated by the melting of the ice crystals, and not an effect of the serum phase. However, serum phase viscosity did prolong the lag time, and thus delayed the start of the melting process. These results show that different anti-freeze agents control both the structural and physical properties of model frozen desserts and give new tools for the formulation of low-sugar products. • Ice crystal size was influenced by freezing point and Mw of anti-freezing agents. • Smaller ice crystals led to harder texture due to increased ice connectivity. • Serum phase viscosity influenced hardness only in samples with small ice crystals. • Larger ice crystals increased melting rate by faster serum flow and heat transfer. • Ice crystal network was the dominant factor governing texture and rheology.