Moisture sorption characteristics of lal peda at different storage temperatures

Abstract

Moisture sorption isotherms of lal peda, a heat-desiccated traditional milk product of Indian sub-continent were determined at 10, 25 and 37°C over a water activity range of 0.113 to 0.868 using standard saturated salt solutions. The isotherms obtained were of sigmoid shape (type II) at all temperatures. Among five sorption models fitted, Guggenheim–Anderson–de Boer (GAB) model was fitted best to the sorption at three temperatures. The monolayer moisture content as calculated by the best fitted GAB model for desorption and adsorption processes at 10, 25 and 37°C were 3.852, 4.551 and 5.235 and 3.214, 4.103 and 5.253% on a dry basis, respectively. The values of isosteric heat of sorption as calculated from Clausius–Clapeyron equation was found to increase with decreasing moisture content at lower moisture content.