Structural and functional differences between ice crystal-dominated and fat network-dominated ice cream

Abstract

In this study, we investigated the effect of overrun, fat destabilization degree and ice crystal size on viscoelastic behavior, hardness and melting properties of ice cream by changing only one parameter at a time. To vary the degree of fat destabilization, we changed the emulsifier type; to modify overrun and ice crystal size, we used either a batch freezer or liquid nitrogen freezing upon whipping. Fat destabilization degree, overrun and ice crystal size were measured to determine the structural differences between the studied samples. Furthermore, viscoelastic behavior upon increasing strain and temperature were evaluated by oscillatory rheology. Hardness and meltdown tests were performed to explore the role of different microstructural elements. Depending on the composition of the ice cream, we identified two main types of structures: one dominated by the ice crystals, and one dominated by a fat network. The results showed that the ice crystal-dominated structure contributed more than the fat network to viscoelastic behavior and hardness, whereas the fat network had a larger effect on the melting process. Only a limited effect of ice crystal size on the properties of the ice cream was seen, independently of the kind of dominated structure. In both types of ice cream, overrun had a large effect on mechanical properties, but only in ice crystal-dominated samples it also affected melting. This research provides a better understanding of the role of multiple structural elements in ice cream, which can be used for its reformulation.