Water agar-agar equilibrium: determination and correlation of sorption isotherms.

Summary Water activity in hygroscopic solids determines the behaviour of many materials in storage as well as in drying and freezing operations. Available data concerning phycocolloid gels, such as those of agar-agar and derivatives, are scarce in spite of their interest for pharmacology and the food industry. Thus, we have determined the isotherms of adsorption and desorption of agar-water gels by means of a gravimetric procedure, at 25, 40, 60 and 80 °C, determining the effect of temperature on the heat of desorption by the isosteric heat method, using the Henderson model. [ABSTRACT FROM AUTHOR]