Thermodynamic properties of pepper seeds - variety ‘Cabacinha’

Abstract

Drying is one of the most important steps of the post-harvest of pepper seeds and must be performed carefully so as not to impair the quality of seeds. The study of thermodynamic properties provides information about the behavior of water in agriculture products and the energy requirement for removal thereof during the drying pro­cess. Based on the above, this study aimed to determine and evaluate the thermodynamic properties for different equilibrium moisture contents in pepper seeds of the variety ‘Cabacinha’. Seeds with an initial moisture content of 22.7% on dry basis (d.b.) were subjected to drying at 40 °C, until reaching moisture content of 3.9% (d.b.). Based on the obtained results, it is concluded that the integral isosteric heat of desorption, the Gibbs free energy, the differential enthalpy and entropy increase with the reduction of the moisture content of pepper seeds. The Gibbs free energy showed positive values, indicating that the process of desorption is not spontaneous. The theory of the enthalpy-entropy compensation can be applied to the desorption process, since this is controlled by enthalpy.