Desorption isotherms for sweet and sour cherry

For sorptional data to be useful in simulation and design purposes, they must be represented by equations valid in a range similar than the used in the industrial practice. In this regard sorptional models accounting for the influence of temperature on equilibrium values or desorption isotherms are most valuable. In this work, water desorption isotherms were experimentally determined, by the gravimetric method, for fresh sweet and sour cherries (X-db = 3.54 and 3.39 respectively). According to the ANOVA test, no significant differences among experimental values of both fruits were found. Seven models were tested to mathematically represent the moisture content as a function of water activity (in the range of 0.11-0.85) and temperature (20, 40 and 60 degreesC), for further use in process simulation. Those more accurate were the three-parameter GAB, the Iglesias & Chirife and the Ratti models. Any of the three models should be used to predict sorptional equilibrium values in the range tested, but the Ratti equation had the best statistical error. (C) 2003 Elsevier Ltd. All rights reserved.