Moisture Isotherms and Heat of Desorption of Pistachio (Kaleghochi Var.)

Abstract

Moisture desorption isotherms (EMC/ERH) of Iranian pistachio variety of Kaleghochi were determined at 45, 60, 75 and 90°C using the standard gravimetric static method over a range of relative humidity from 10% to 82%. The experimental desorption curves were fitted under the following different equations: modified Henderson, modified Chung-Pfost, modified Halsaey and modified Oswin. The modified Oswin model was found to be a suitable model for describing the desorption isotherms of pistachio. The net isosteric heat of desorption of pistachio was also determined from the equilibrium data at different temperatures. Furthermore, the net isosteric heat of desorption of pistachio varied between 13.2 – 2.2kJ/mol at moisture varying between 2.5 – 15% (d.b).