Abstract
The glass transition in protamines, mainly salmine (from salmon), in the presence of maltose or dextran has been studied using differential scanning calorimetry. The water activities (Aw) of salmine and its mixtures with maltose or dextran were adjusted from Aw 0.11 to 0.93 and state diagrams showing relationships between glass transition temperature (Tg), Aw and water content were established. The adsorption isotherms and Tg-water content relations were obtained by applying the Guggenheim-Anderson-Deboer equation and the Gordon-Taylor equation, respectively. Salmine used in this study was in a glassy state (Tg=about 140°C at 0% water content) and its Tg value decreased with increasing water content. The Tg values of salmine were reduced in the presence of maltose, while increased by mixing with dextran. The Tg of the maximally freeze-concentrated phase of salmine (Tg') was found out to be -5.8°C.
