ABSTRACT
This chapter discusses water plasticization occurring in food and related systems and, in particular, in amorphous sugars and starch, emphasizing the relationships between glass transition, water plasticization, and time-dependent changes in crystallinity. Temperatures of the glass transition ranges of biomaterials and foods are particularly dependent on the presence and amount of water, which is the main plasticizer of carbohydrates, proteins, and other water-soluble or water-miscible compounds. The glass transition is one of the most important changes in the physical state of concentrated biological and food materials. The ascending translational mobility of molecules over and above the glass transition temperature range is likely to affect material flow and rates of changes occurring in foods. As a result of plasticization to the glass transition, that is, in supercooled liquid state, the viscosity decreases dramatically, allowing an increase in molecular mobility and translational motions.
