DSC Measurement of Frozen Water in Liquid Foods

Abstract

We investigated the state of water in frozen liquid foods, supposed to influence the performance of freeze-drying, by DSC. The amount of unfreezable water in milk was constant irrespective of the initial water content. As expected from the phase equilibrium, the water content of the non-ice part of CAS was constant among the samples with different initial water contents. The volume fraction of ice crystals, which should be known in the analysis of the freeze-drying rate, was significantly smaller at the low initial water content than the one usually estimated with the assumption that the water was all freezable.