Selection of fitting models of adsorption and desorption isotherms of rice and optimization of their parameters

In order to evaluate the fitting effects of five most commonly recommended fitting models with adsorption and desorption isotherms of different rice types (indica rice, japonica rice, glutinous rice) of China, and determine the best fitting model and its parameters, non-linear regression analysis was used to determine adsorption and desorption isotherms of different rice types, and to evaluate the fitting effects and determine their parameters. The results show that modified Chung-Pfost model recommended by ASAE is not effective to fit the isotherms of rice, while Strohman-Yoerger model (STYE) fits the adsorption and desorption isotherms of japonica and indica rice and the adsorption isotherms of Zhennuo variety best of the five. But modified-Oswin equation(MONE) is the best one fitting desorption isotherms of Zhennuo variety of the five. The parameters (C₁, C₂, C₃, C₄) of the STYE fitting adsorption isotherms of indica and japonica rice are 1.44871, 0.20898, 7.32345, 0.18647, for desorption isotherms, the parameters are 2.25071, 0.24167, 8.32543, 0.19035, and for adsorption isotherms of Zhennuo variety, the parameters are 1.55680, 0.19179, 6.19676, 0.17155, respectively. The parameters (C₁, C₂, C₃) of the MONE fitting desorption isotherms are 13.63642, -0.05638, 3.60042, respectively. The results provide fundamental data for rice preservation and processing in China.