Shrinkage and Storage Stability of High-Protein, High-Overrun Frozen Desserts

Shrinkage is a significant quality issue that affects many frozen desserts and is especially prevalent in frozen desserts with increased protein and/or air content. While the mechanism of shrinkage is not well understood, this experiment sought to understand the structural and interfacial role of dairy proteins and other surface-active ingredients in forming and stabilizing the microstructure of the product to identify physicochemical phenomena associated with air phase destabilization. The source of dairy protein and addition of mono- and diglycerides influenced the structure of the ice, air, fat, and serum phases, which, in combination, affected the stability of the product during melting and during temperature-cycled storage. Frozen desserts that had a greater degree of fat destabilization collapsed more slowly at room temperature and had smaller mean ice and air cell size after 6 weeks of storage, in part due to the cooperative structuring effects of mono- and diglycerides, serum proteins, and micellar casein. In frozen desserts made with flexible casein proteins, severe air phase destabilization occurred and facilitated ambient collapse and shrinkage of the product during storage. Proteins and other ingredients are essential to the stepwise development of frozen dessert microstructure. Investigating the role of these structures in foam stability at room temperature and instability during storage is essential to elucidating a mechanism of shrinkage and optimizing frozen desserts to resist this defect. PRACTICAL APPLICATIONS: This research highlights the roles of surface-active ingredients in the development of microstructure during freezing and storage and demonstrates that high-protein, high-overrun frozen desserts can be formulated to resist recrystallization and shrinkage during storage.