Determination and analysis of water desorption and adsorption isotherms of macadamia nut kernel flour

In order to provide technical data for macadamia nut kernel flour drying and preservation, adsorption and desorption isotherms of macadamia nut kernel flour at room temperature (25℃) were determined. Non-linear regression analysis was used to evaluate the fitness of the commonly used models as BET, GAB, Halsey, Henderson, Oswin and Smith based on the experimental data, and to determine the best models and their parameters. The results showed that the obtained desorption isotherm was of type Ⅱ, and the adsorption was of type Ⅲ according to IUPAC classification. The hysteresis loop was of type H3. The best model fitted for desorption isotherm was GAB model, and that for adsorption was Henderson model. The parameters (A, B, C) of GAB model for desorption isotherm were 8.2439, 0.4815 and 1.3545, respectively. The parameters (A, B) of Henderson model for adsorption isotherm were 0.3006 and 0.8682, respectively.