Moisture sorption isotherms of castor beans. Part 2: Thermodynamic properties

Isotermas de sorção de grãos de mamona. Parte 2: Propriedades termodinâmicas

ABSTRACT

Knowledge on the water sorption within agricultural products is extremely important for decision making during post-harvest procedures. In order to improve this knowledge, thermodynamic properties regarding water sorption provide useful data. Thermodynamic properties of castor beans, related to sorption, were determined. Static gravimetric technique under different conditions of temperature (25, 35, 45 and 55 ± 1 °C) was used. Saturated salt solutions in the range of 37-87% ± 2% were utilized to create the required controlled humidity environment. After the sorption procedure, differential enthalpy, differential entropy and Gibbs free energy of this process were calculated and decreased with increased values of equilibrium moisture content.

Key words:
Ricinus communis L.; moisture content; enthalpy–entropy compensation theory