J. Phys. IV France 122 (2004) 235-240
Experimental study and modelling of water sorption/desorption isotherms on two agricultural products: Apple and carrotS. Timoumi1, F. Zagrouba1, D. Mihoubi1 and M.M. Tlili2
1 Laboratoire d'Énergétique et des Procédés Thermiques, Institut National de Recherche Scientifique et Technique, BP. 95, 2050 Hammam-Lif, Tunisie
2 Laboratoire de Géochimie et de Physico-Chimie de l'Eau, Institut National de Recherche Scientifique et Technique, BP. 95, 2050 Hammam-Lif, Tunisie
This work is focused on some properties of dried apple (Red Chief) and carrot (Misky). Water sorption isotherms of carrot and apple were investigated at three temperatures: 30, 40 and 60°C, corresponding to drying temperatures, by the static method consisting of the use of different sulphuric acid solutions. Guggenheim-Anderson-de Boer (G.A.B) model is found to describe the experimental curves better than Henderson, Hasley and Oswin models with a correlation coefficient superior to 0.97 for both products. The hysteresis phenomenon was clearly observed in the case of apple isotherms. The experimental data were also used to determine the isosteric enthalpy of desorption of apple and carrot. The isosteric enthalpy of desorption decreased with increase in moisture content and the trend became asymptotic.
© EDP Sciences 2004