Evaluation of thermodynamic properties using GAB model to describe the desorption process of cocoa beans

• Autor(a) principal: Oliveira, Gabriel Henrique Horta de
• Data de Publicação: 2011
• Outros Autores: Corrêa, Paulo Cesar, Santos, Emı́lio de Souza, Treto, Pedro Casanova, Diniz, Mayra Darliane Martins Silva
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2621.2011.02719.x; http://www.locus.ufv.br/handle/123456789/22428
• topic: Entropy; Gibbs free energy; Isosteric heat; Monolayer moisture content; Theobroma cacao

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.