Moisture Adsorption Isotherms and Isosteric Heat of A Variety of ‘Deglet Nour’ Dates Harvested in the Guerrara (Ghardaïa, Algeria) Region

The objective of this study is to determine the sorption isotherms and thermodynamic properties of the Deglet Nour variety of dates harvested in the Guerrara region (Algeria), through experimental and mathematical analysis following thermal treatments at different temperatures (20 °C, 30 °C, 40 °C, and 50 °C) and water activity (aw) ranged from 0.06 and 96.44 %. Specifically, we aim to establish the relationship between the water activity (aw) and the equilibrium moisture content (EMC) of the tested product. The gravimetric method using sulfuric acid solutions has been selected as the preferred technique. To model and predict the hygroscopic behavior during the processes of drying and storage, a total of nine mathematical models have been employed, namely the GAB, BET, Smith, Henreson, Halsey, Igesias, Oswin, Caurie and Peleg. The best-fitting equations were Oswin, Caurie and Peleg. The outcomes of this investigation hold the potential for identifying distinctive drying curves and establishing optimal storage conditions.