Model comparisons of equilibrium moisture content of prunes in the temperature range of 15-45 degrees C

Moisture equilibrium data for adsorption and desorption of water from prune s (Prunus domestica L.) were investigated at temperatures in the range of 1 5-45 degrees C and water activity ranging from 0.4 to 0.99. The experimenta l procedure used was a gravimetric dynamic method with continuous registrat ion of sample weight changes. A special laboratory drying device has been d eveloped for the purpose. Sorption capacity decreases as temperature increa ses. The differences between equilibrium moisture contents at a constant wa ter activity were small in the temperature range measured. Rehydration of t he dried material results in hysteresis. Four models available in the liter ature (Chung-Pfost, Halsey, Henderson, and Oswin) were evaluated to determi ne the best fit for the experimental data. The modified Halsey equation was a good model for moisture adsorption and desorption of prunes. (C) 1998 El sevier Science Ltd. All rights reserved.