Equilibrium Sorption Isotherms of Damask (Rosa Damascena Mill.) Rose Flowers

Products from Rosa Damascena Mill. (Damask rose) have a very wide use in medicine, food, cosmetics, skin care, aroma therapy, and beverage fields. In recent years, the international demand for "dried damask rose petals or whole flower petals" is increasing. Optimum drying air temperature and relative humidity should be determined to ensure proper storage conditions for Damask rose. The equilibrium moisture content of Damask rose whole flower petals or "Damask rose" was determined by static gravimetric method at 25, 30, 35, and 40 degrees C. Five different mathematical models including Oswin, Peleg, Henderson, Iglesias-Chirife, and Smith describing the sorption isotherms of Damask rose were used to predict the experimental data. The results showed that at the same water activity, equilibrium moisture content increased with a decrease in temperature. On the other side, at the same temperature, the equilibrium moisture content increased with an increase in water activity. Hysteresis effect was dominant for the Damask rose obtained at 25 degrees C at water activity ranging from 0.2 and 0.8. The highest predictive performance was acquired by the Peleg model for the experimentally obtained desorption and adsorption isotherms of Damask rose.