Resumen de Thermodynamic Analysis of Water Vapour Sorption of Edible Starch Based Films

J.C. Gottifredi, M. Armada, M.A. Bertuzzi

• Moisture sorption isotherms of high amylose corn starch (HACS) films at 5, 25, 35 and 45 ºC within an approximate water activity (aw) range of 0.11-0.85 were obtained using a static gravimetric method. HACS films fitted a type III BET model at all temperatures studied. Water sorption process in high amylose based films was exothermic within the range of water activities investigated. There was a continuous decrease of the affinity between film sorbed structure with moisture as water content increased. Negative values of deltaG in the whole range of moisture content studied were indicative of a spontaneous process. The entropy curve exhibited a well-defined mínimum corresponding at the completion of the monolayer (A)