Artigo
Evaluation of thermodynamic properties using GAB model to describe the desorption process of cocoa beans
Autor
Oliveira, Gabriel Henrique Horta de
Corrêa, Paulo Cesar
Santos, Emı́lio de Souza
Treto, Pedro Casanova
Diniz, Mayra Darliane Martins Silva
Institución
Resumen
The desorption isotherms and thermodynamic properties of cocoa beans were obtained during the drying process of this product. The isotherms were determined by dynamic method for various temperature (25, 35,45 and 55 C) and relative humidity (RH) conditions (30, 40, 50, 60, 70 and 80%). Equilibrium moisture content data were correlated by the Guggenheim–Anderson–de Boer (GAB) model, which presented good fit to the data, according to statistical procedures. Equilibrium moisture content ranged from 5.90 to 16.67 d.b.; it increased with an increment in the RH and decreased with increased temperature at a constant RH.Enthalpy values for each model coefficient were encountered, ranging from )90.05 to 545.96 kJ kg )1 . The integral isosteric heat of desorption and differential entropy increased with decreased equilibrium moisture content, a tendency also found for Gibbs free energy.