Experimental determination of the sorption isotherms of mint

The equilibrium water content of a product to be dried is essential during storage and solar drying operation by forced convection. These values are often taken from the so-called sorption isotherm graphs. The determination of these isotherms is an essential step to knowing the distribution and the intensity of the water bonds in the products in use. They allow determining the final water content to be reached to optimize the drying conditions of these products and give valuable information on the hygroscopic equilibrium. Therefore, the present work proposes to determine experimentally the desorption isotherms of a medicinal and aromatic agricultural product (mint), using the saturated saline solution method. The experiment is carried out for four different values of temperature: 20°C, 35°C, 45°C and 55°C to study the influence of temperature on the equilibrium graphs of the product and to describe the desorption isotherm of mint for each temperature using a polynomial regression of the experimental points found. Finally it was compared with the Henderson model.