Modelling of water vapour adsorption on foods products by a statistical physics treatment using the grand canonical ensemble

Knowledge of water adsorption isotherms is very important with regard to concentration, dehydration and drying of food products as well as determining the quality, stability and the shelf life of foods. A new analytical isotherm equation that can be applicable to water vapour-food systems similar to BET equation but modified is developed using the grand canonical ensemble in statistical physics. The establishment of the expression model is based on a statistical physics treatment and some working hypothesises. We mainly introduce four parameters affecting the adsorption process, namely, the density of water receptor sites N-M, the number of water molecules per site and the water adsorption energies. The proposed model is applied to experimental water adsorption isotherms taken from the literature. The fitting of the experimental curves with this model showed an improvement of the coefficient of determination R-2 in comparison with the BET model and other equations. (C) 2011 Elsevier Ltd. All rights reserved.