Sorption isotherms and thermodynamic properties of peppermint tea (Mentha piperita) after thermal and biochemical treatment

Moisture sorption isotherms of peppermint tea treated by thermal and biochemical process were determined at 30, 40 and 50°C using the static gravimetric method. GAB model found to be the most suitable model for describing the sorption curves among three well-known tested equations. Thermodynamic properties such as differential enthalpy and entropy of sorption were determined from moisture adsorption and desorption data, using the Clausius-Clapeyron equation. The experimental data showed that enthalpy-entropy compensation theory was applicable to the moisture sorption behaviour of peppermint tea.