Moisture sorption isotherms of black gram nuggets (bori) at varied temperatures Original Research Article

Adsorption–desorption behaviours of bori nuggets prepared from black gram pulse were studied at different relative humidity (ERH) ranging from 0% and 85% and temperatures at 25, 35, 45 and 55 °C following the static equilibriation technique using the saturated solutions of various salts. These data were analysed and fitted Guggenheim–Anderson–de Boer (GAB) sorption model. The temperature dependence of the respective coefficients revealed that the GAB model is acceptable (r2⩾0.99; MRES ⩽ 0.481) in describing the EMC–ERH relationships of the nuggets. The M0, C and K values were in the range of 8.35–8.24, 82.28–41.04 and 0.74–0.72 for adsorption. The corresponding values for desorption are 9.52–8.77, 107.83–39.68 and 0.74–0.73. The net isosteric heats of sorption estimated from the Clausius–Clapeyron equation, decreased exponentially from 5.94 to 2.52 kJ mol−1 with the increase in moisture content of the sample 5–24% (db) for adsorption. The corresponding values were 8.42 to 3.42 kJ mol−1 for desorption.