Water desorption and thermodynamic properties of okra seeds.

TLDR: In this paper, the authors determined desorption isotherms of okra seeds for diverse conditions of temperature (10°C to 50°C) and relative humidity (0.11 to 0.96) of the air.

Abstract: The objective of the present work was to determine desorption isotherms of okra seeds for diverse conditions of temperature (10°C to 50°C) and relative humidity (0.11 to 0.96) of the air, as well as determine the values of isosteric heat of desorption, differential entropy, and Gibbs free energy. To obtain the equilibrium moisture content, a static method was used. Experimental data were adjusted to frequently used mathematical models for representation of hygroscopicity of agricultural products. Calculation of the net isosteric heat of desorption was performed based on the Clausius-Clapeyron thermodynamic relation. From the obtained results, it was concluded that equilibrium moisture content of the okra seeds decreased with an increase in temperature at the same relative humidity, as is the case of the majority of agricultural products. Based on statistical parameters, the Chung-Pfost model best represented the hygroscopicity of the okra seeds. Values of the integral isosteric heat of desorption as well as the differential entropy and Gibbs free energy for the okra seeds decreased with an increase in moisture content.