Water and Molecular Weight Effects on Glass Transitions in Amorphous Carbohydrates and Carbohydrate Solutions

ABSTRACT The effects of water, freeze‐concentration and effective molecular weight (M e ) on glass transition (T g ) of maltose and maltodextrins were studied, and methods to predict T g were used to establish state diagrams. T g of maximally freeze‐concentrated solutes (T′ g ) and onset of ice melting (T′ m ) increased with M e , and for high molecular weight polysaccharides T′ g and T′ m were predicted to have the same temperature value. Ice formation at T′ g <T < T′ m was time dependent. Unfrozen water in maximally freeze‐concentrated matrices was about 20% independently of M e . The state diagrams can be used to evaluate physical state of frozen and dehydrated foods.