The effect of encapsulants on the heat of sorption in vacuum-dried cajá powder

Abstract

Equilibrium moisture data from the powdered pulp of Spondias mombin, L., both with and withoutadditives -58% maltodextrin (MD) or 58% gum arabic (GA) -were determined at 20, 30, 40 and 50 °C, using the staticgravimetric method for a water activity range of 0.06 to 0.90. The resulting isotherms were sigmoidal and typical TypeIII, with the Guggenheim-Anderson-de-Boer model (GAB) adjusted to the experimental data for equilibrium moisturevs water activity. The addition of additives was shown to affect the isotherms in such a way that, for the same wateractivity, samples of CP+GA and CP+MD showed a lower equilibrium moisture content and were not affected by thevariations in temperature. The isosteric heat of sorption for the cajá powder with additives was greater (less negative)than that of the cajá powder with no additives, suggesting that polar sites in the product without the addition of GA orMD are more active. An empirical exponential relationship can describe the dependence of the heat of sorption as afunction of the moisture content of the material.