Moisture adsorption isotherms of the borojó fruit (Borojoa patinoi. Cuatrecasas) and gum arabic powders

• The GAB model provided a good representation of the moisture adsorption of powders.
• Monolayer values were close to corresponding to minimum integral entropy.
• The adsorption process was driven by enthalpic mechanisms due to high sugar content.
• The addition of gums to borojó powders modifies the water adsorption during storage.

Sorption mechanisms of borojó pulp (BPP), three borojó phases (liquid phase (LP), medium phase (MP) and solid phase (SP)), gum arabic (GA), and a mixture of these (BP) produced by freeze-drying were interpreted through adsorption isotherms. The adsorption models adequately describe the experimental data over the entire measured range of aw; R2 was close to 1 for the studied conditions. For the thermodynamic properties, the differential and integral enthalpy of BP showed a synergic effect of the combined components. This shows that using a combination of polymers increases the interaction energy of water molecules with the surface of the material. The monolayers from the BET and GAB models showed similar moisture content values that corresponded to the minimum integral entropy. Finally, the behavior of the enthalpy–entropy compensation of water adsorption for the SP, MP and GA powders at low moisture contents demonstrated that the content is controlled by an entropic mechanism, for BP, BPP and LP powders, the water adsorption may be considered as mainly enthalpy-driven.