EQUILIBRIUM MOISTURE-CONTENT AND HEAT OF DESORPTION OF SOME VEGETABLES

The equilibrium moisture content of potato, carrot, tomato, green pepper and onion was determined within the range of 10 to 90% water activity at three different temperatures (30, 45 and 60-degrees-C), using the standard static gravimetric method developed by the European Cooperation Project COST 90. The GAB equation was fitted to the experimental data, using the direct nonlinear regression analysis method and the agreement between experimental and calculated values was satisfactory. The net isosteric heat of desorption of water was determined from the equilibrium desorption data, using the Clausius-Clapeyron equation, An empirical exponential relationship between the net isosteric heat of sorption and the moisture content was proposed and validated.