Abstract
Water is an overwhelmingly major component in food so that the freezing behavior is very important in food processing. Effective thermal conductivity of frozen food is strongly dependent on temperature and is described well by the Maxwell-Eucken model with ice phase dispersed. Ice crystal structure size in frozen food is inversely proportional to the advance rate of ice front, reflecting the important role of the molecular diffusion of water in the process of ice crystal growth. In the freezing preservation of living cells, the water permeability in the plasma membrane seriously affects freezing tolerance of cells. Plant cells, in general, have much lower water permeability in the membrane as compared with animal and microbial cells so that the membrane structure of plant cells is easily destroyed by freezing. This lower freezing tolerance of plant cells is applicable to the waste treatment of kitchen refuses such as vegetables and fruits. By controlling the ice crystal structure size very large, the progressive freeze-concentration becomes possible. This method is very effective to make the freeze concentration system much simpler as compared with the conventional method of suspension crystallization to reduce the cost of freeze concentration substantially.
