Solute inclusion during progressive freeze concentration: A state diagram approach

Abstract

We propose a conceptual model for progressive freeze concentration, which predicts solute loss through inclusion in the ice based on the system's phase behaviour as illustrated in a state diagram. We compare the outcomes of the model for sodium chloride, sucrose, and bovine serum albumin (BSA). For ice growth rates in the order 10−2 μm/s there was no solute inclusion for sodium chloride or sucrose, but above this range, local super-cooling gives rise to a freezing zone. In this freezing zone ice and solution co-exist and the resulting uneven advancement of the ice causes inclusions. The model predicts that for macromolecular solutions such as BSA, no inclusion will take place through the proposed mechanism.