Thermodynamic properties of water desorption of forage turnip seeds

• Autor(a) principal: Sousa, Kelly Aparecida
• Data de Publicação: 2014
• Outros Autores: Resende, Osvaldo, Goneli, André Luis Duarte, Smaniotto, Thaís Adriana de Souza, Oliveira, Daniel Emanuel Cabral de
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Acta Scientiarum. Agronomy (Online)
• Texto Completo: http://www.periodicos.uem.br/ojs/index.php/ActaSciAgron/article/view/19333
• topic: hygroscopic equilibrium; isosteric heat; gibbs free energy; compensation theory

The purpose of this study was to determine the thermodynamic properties of the process of water sorption in forage turnip  seeds. The equilibrium moisture content of forage turnip  seeds was determined by the gravimetric-dynamic method for different values of temperature and water activity. According to the results, increasing the moisture content increases the energy required for the evaporation of water in forage turnip seeds, and the values of integral isosteric heat of desorption, within the moisture content range of 3.33 to 11.30 (% d.b.), varies from 4,222.70 to 2,870.34 kJ kg-1. With the elevation in the equilibrium moisture content, there is an increase in differential entropy and Gibbs free energy, which has positive values, demonstrating non-spontaneity in the process of desorption in the seeds. The theory of enthalpy-entropy compensation can be satisfactorily applied to the sorption phenomenon, and the process of water desorption of forage turnip seeds is controlled by enthalpy.