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

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.