In the paper, there were determined and described the water vapour adsorption isotherms of dried orange and purple carrots using BET, GAB, Lewicki, Oswin, Halsey, and Peleg mathematical models. The orange carrots of Bolero cultivar and purple carrots of Deep Purple cultivar were dried using four methods: convective, infrared-convective, microwave-convective, and freeze drying. A static-desiccator method was applied to determine the sorption isotherms. The usefulness of models for describing isotherms was assessed on the basis of root mean square error (RMS). According to the BET classification, the water adsorption isotherms of dried orange and purple carrots were characterized by a III isotherm type characteristic for high sugar content products. The pattern of isotherms depended on the drying method applied. The GAB model was the best to describe the sorption isotherms; however, only the freeze-dried orange and purple carrot isotherms were well matched, and, in this case, the RMS error values were 0.07 and 0.09, respectively. All other RMS error values of mathematical models describing the absorption isotherms exceeded 0.25; it means that those models cannot be used to describe the water vapour adsorption pattern of the dried carrots investigated. Regardless of the used model, the best fit of models were for freeze dried samples (Ve = 3,3 – 8,5 %). The dried purple carrots were characterized by a higher equilibrium water content in the monolayer; therefore, their storage stability was potentially higher than that of the dried orange carrots.
drying, carrot, adsorption isotherms, mathematic models