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

摘要

Sorption mechanisms of borojo pulp (BPP), three borojo 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 au); 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. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.