糖質におけるガラス転移特性の制御と食品の品質設計

抄録

The glass transition property of carbohydrate materials and its practical significance for the quality control of food are reviewed. Carbohydrate materials exist, at least partially, in an amorphous state and thus a glass transition occurs during dehydration/rehydration and/or freeze/thaw processing. Since rheological properties are changed drastically by the glass transition, it is of practical importance to understand the glass transition temperature (T_g) and freeze-concentrated glass transition temperature (T_g'). The T_g of carbohydrate materials increases with an increase in the molecular weight depending on the types of monomer and chemical bond, and decreases with increase in the moisture content. Semi-crystalline carbohydrate polymers have slightly higher T_g than amorphous carbohydrate polymers. Effect of molecular weight on the T_g' is a roughly similar trend to the T_g. It is well known that a cookie is a typical carbohydrate enriched glassy food. The T_g of a cookie decreases with an increase in water content. In addition sugar composition plays an important role in the T_g of cookie products; the T_g of a cookie increases sensitively with an increase in the T_g of sugar composition used. This suggests that physical properties of a cookie is governed by the amorphous sugar matrix, and that the texture and storage stability of a cookie can be designed by the T_g based on the sugar composition.