Physical and moisture sorption thermodynamic properties of Sukkari date (Phoenix dactylifera L.) powder

Abstract

Physical properties of Sukkari date powder (SDP) at different particle sizes, namely, moisture content, water activity, tapped and bulk densities, compressibility index, Hausner ratio, water absorption, and solubility indices, swelling capacity, and color parameters were experimentally determined. The SDP moisture sorption experiments were conducted using a dynamic vapor sorption instrument in the relative humidity range 10%–90% at 20, 40, and 60°C. Among the ten tested sorption models, the GAB and modified GAB models best fitted SDP sorption data. The monolayer moisture content decreased with increasing temperature. The differential enthalpy and entropy, and net integral enthalpy and entropy decreased consistently with increasing moisture content. The linear relationship between differential enthalpy and entropy confirmed the applicability of the compensation theory. The estimated values of the isokinetic and harmonic temperatures and the Gibbs free energy change revealed that the sorption process is non-spontaneous and enthalpy driven.