Solar convective drying kinetics and sorption isotherms of Citrus aurantium flowers

Citrus aurantium flowers are high value aromatic and medicinal plants. The storage conditions and quality of dried Citrus aurantium flowers depends on their hygroscopic stability. The equilibrium moisture content was determined at temperatures (from 30 to 60 degrees C), and the sorption phenomenon is well described by Peleg model. The optimal water activity for the storage of the product was estimated at a(wop)=0.373. Afterwards, the net isosteric heat was evaluated in the range of 88 kJ.mol(-1) for small values of the moisture content (X-eq=0.14kg water/kg d.b), and it decreased along with the increase of X-eq. The experimental drying curves showed only a falling rate period. Finally, Midilli-Kucuk model was found to be the more suitable to describe the drying kinetic of Citrus aurantium flowers.