Applicability of the generalised D’Arcy and Watt model to description of water sorption on pineapple and other foodstuffs

In this paper we adapt (developed by us recently) the Generalised D’Arcy and Watt (GDW) model to the description of water vapour sorption on foodstuffs. We show that this simple formula can successfully describe the set of sorption isotherms measured on pineapple (in the range of temperatures 20–50 °C) and reported in this journal by Hossain et al. [Hossain, M. D., Bala, B. K., Hossain, M. A., & Mondol, M. R. A. (2001). Sorption isotherms and heat of sorption of pineapple. Journal of Food Engineering, 48, 103–107]. Presented model also describes the isosteric enthalpy of sorption reported by those authors. We also show the applicability of GDW model to description of water sorption data on other foodstuffs (macaroni, sardine and pistachio nut paste) and we prove the inconsistency of the modified BET equation. Having strong kinetic basis, our model makes it possible to suggest the mechanism of water adsorption on foodstuffs, and can be successfully applied by researchers who are looking for mathematical equations to describe the sorption isotherms of food materials and/or calculate some parameters characterising water sorption mechanism.