Investigating Hysteresis Effect and Monolayer Moisture Adsorption of Canola

Canola is a prominent oil seed crop with a very high production potential in Iran and the production process of which needs to be optimized. Drying is an important part of the processing of the crop with EMC values playing a vital role in the process. In this research adsorption and desorption experiments were conducted in an environmental chamber for Licord variety of canola. The thin layer experiments were run in three replications at constant air temperature of 55? and relative humidity between 7% and 84% (8 points). The thermodynamic conditions (temperature and relative humidity) were maintained in the environmental chamber. Temperature was kept constant at 55? via an accurate thermostat and relative humidities were controlled using saturated salt solutions. Referring to the isotherm sigmoid shape curves for adsorption and desorption showed that the desorption EMC ones were more than the adsorption EMC values at constant temperature. The hysteresis effect can be clearly shown through adsorption-desorption curves. In order to find the best predictive EMC model, thirteen mathematical models namely, Oswin, Modified Smith, Modified Oswin, Modified Henderson, Modified Halsey, Modified Chung- pfost, Modified BET, Chung-pfost, Kuhn, Henderson, Halsey, GAB and Caurie were selected for fitting the experimental data. The goodness of fit was evaluated by coefficient of determination (R2), chi-square (?2) and root of mean square error (RMSE). The GAB model showed the best results for both desorption and adsorption processes. The values of coefficient of determination (R2), chi-square (? 2) and root of mean square error (RMSE) were 0.997, 0.023 and 0.120 for adsorption and 0.994, 0.031 and 0.140 for desorption processes respectively. The adsorption monolayer moisture content (m0) was evaluated using BET equation. The monolayer moisture content was calculated 1.555 (%d.b.) and the corresponding constant value in the BET equation was found as -10.371.