Determination of EMC isotherms and appropriate mathematical models for canola

Canola seed needs to be dried to minimize damage during subsequent unit operations. In order to optimize the drying and storage processes of seeds it is necessary to know the equilibrium moisture content at different air equilibrium relative humidities and temperatures. In the present work adsorption equilibrium moisture content isotherms were determined for a specific local canola variety at 25, 40 and 55 °C and seven air relative humidifies within the range of 11–90%. Experimental data were used to model the adsorption isotherm process using non-linear regression analysis. Thirteen available mathematical and semi empirical models were employed to find the best fit isotherm curve model. The Halsey model showed the best results at 25 and 40 °C and the values of coefficient of determination (R2), chi-square (χ2) and root of mean square error (RMSE) were 0.993, 0.122 and 0.295 at 25 °C and 0.994, 0.042 and 0.174 at 40 °C. Another best fit mode was the GAB model at 55 °C which resulted in the values of 0.997, 0.023 and 0.120 for R2, χ2 and RMSE respectively. The adsorption monolayer moisture content (m0) was also evaluated using BET equation. The m0 values at 25 °C, 40 °C and 55 °C were 0.017, 0.016 and 0.015 g H2O/g solid and the corresponding constant values of the BET equation were found to be −4.733, −5.129 and −10.299 respectively.

Research highlights▶ Canola EMC determination at 25, 40 and 55 °C. ▶ Canola monolayer moisture content determination at 25, 40 and 55 °C. ▶ Best fit isotherm models for canola adsorption.