Model comparisons of equilibrium moisture content of prunes in the temperature range of 15–45°C

Abstract

Moisture equilibrium data for adsorption and desorption of water from prunes ( Prunus domestica L.) were investigated at temperatures in the range of 15–45°C and water activity ranging from 0.4 to 0.99. The experimental procedure used was a gravimetric dynamic method with continuous registration of sample weight changes. A special laboratory drying device has been developed for the purpose. Sorption capacity decreases as temperature increases. The differences between equilibrium moisture contents at a constant water activity were small in the temperature range measured. Rehydration of the dried material results in hysteresis. Four models available in the literature (Chung–Pfost, Halsey, Henderson, and Oswin) were evaluated to determine the best fit for the experimental data. The modified Halsey equation was a good model for moisture adsorption and desorption of prunes.