Water sorption isotherms and air drying kinetics modelling of the brown seaweed Bifurcaria bifurcata

Air drying kinetics at 35, 50, 60 and 75 °C and water adsorption and desorption isotherms at 5, 25, 40 and 55 °C of the brown seaweed Bifurcaria bifurcata were obtained. Water sorption isotherms were modelled by means of the two-parameter Halsey model. A model to estimate equilibrium moisture content of adsorption and desorption processes as function of water activity and temperature simultaneously was obtained by means of linear correlations of Halsey model parameters with temperature. Water sorption isotherms were analysed by a thermodynamic approach to obtain properties such as net isosteric heat of sorption, net equilibrium heat, differential and integral entropy. Monolayer moisture content evaluated by BET model corresponded to the moisture content at which local minimum integral entropy value was observed for sorption processes. Air drying kinetics at different temperatures were modelled using the Page model. The two parameters of the Page model were linearly correlated with temperature. The goodness of the fits was evaluated by evaluation of the coefficients of determination and root mean square errors.