Antiplasticization effect of water in amorphous foods. A review

摘要

Water is the most effective plasticizer in food matrices, decreasing glass transition temperature (T_g) and mechanical resistance and determining a softening effect with the increasing of its concentration. However an opposite effect (i.e. hardening, toughening) could be observed in some food and in specific moisture or a_w range and this is referred to an anti-plasticization effect. Several are the possible causes for this phenomenon and various are the factors that have been recognized to affect its occurrence in a food matrix: mechanical testing method, mechanical parameter tested, type of food (composition and micro-macrostructure). In this paper, several studies on anti-plasticization effect of water are reviewed by focusing the attention on the interactions water-food matrix and in particular to those occurring in amorphous cell foods. The different chemical and physical factors that affect this phenomenon are also discussed. The simultaneous occurrence of a plasticization and anti-plasticization effect of water, even if in different a_w range, and the results of studies on amorphous food matrices may suggest an important effect of water-matrix interaction on the textural properties.