Freezing and dehydration are two common food preservation processes,which,in part,function through the modification of the aqueous environment within the food.In both processes,the mobile aqueous phase becomes more concentrated either as freezing progresses,and more ice is formed,or as dehydration progresses,and more water is removed.The roles of concentration and temperature in the evolution of the various stresses experiencedby frozen and dehydrated systems are compared,and the additiona influence of the presence of ice in frozen systems is examined.The mechanisms of the stresses,the results of the stress,and means to minimize these effects are discussed.Factors considered include osmotic stress,ionic strength effects,volumetric stresses,the influence of phase changes,and the roles of non-ionic and polymeric solutes.These factors are discussed both the terms of model systems,and in terms of a variety of food systems preserved by freezing or by dehydration,and the maintenance of viability in biological systems subjected to freezing or dehydration stresses.
展开▼
