Frozen State Transitions in Freeze-Concentrated Lactose-Protein-Cornstarch Systems

Abstract

Differential scanning calorimetry study of frozen state transitions of mixtures of lactose, proteins, cornstarch, and water revealed that maximum freeze-concentration was achieved by annealing at temperatures T′m-1. The onsets of glass transition of maximally freeze-concentrated solids, T′g, were lower and onsets of ice melting, T′m, were higher for mixtures of proteins and polysaccharide than those of lactose. The established state diagrams showed solids concentrations C′g, of the maximally freeze-concentrated systems of, 82, 78, 78, 78, and 75% for lactose, lactose/albumin, lactose/gelatin, lactose/cornstarch, and lactose/cornstarch/gelatin solutions, respectively. The state diagrams established with experimental and predicted Tg values are useful in characterization of thermal phenomena and physical state of the systems at various water contents and in the freeze-concentrated state.