Desorption and adsorption characteristics of bael (Aegle marmelos) pulp and powder

Moisture desorption isotherm of bael (Aegle marmelos) pulp and adsorption isotherm of pulp powder were determined at 20, 30, 40 and 50°C. Static gravimetric method was used by exposing the samples to controlled atmospheres maintained by saturated salt solutions. The isotherms were found to be of type II sigmoid. Experimental data were fitted to four isotherm models viz. Anderson, Guggenheim–Anderson–de Boer (GAB), Oswin and Peleg models. It was found that Peleg model fits best describing equilibrium moisture content and equilibrium relative humidity (EMC–ERH) relationships for both the bael pulp and the powder. The isosteric heat of sorption varied between 47.5 - 44.55 kJ g^-1 mol^-1 at moisture levels 0.5 - 3.5 g/g dry matter for bael pulp and 46.12 - 44.40 kJ g^-1 mol^-1 at moisture level between 0.25 - 1.125 g/g dry matter for powder.