Solar drying, hygroscopic equilibrium and biochemical quality of Punica granatum legrelliae’s flowers

Punica granatum Legrelliae is a valuable medicinal plant that is widely planted in Morocco. The equilibrium moisture content was investigated. Peleg model was found the most suitable to describe the sorption phenomenon. The drying kinetic of Punica granatum Legrelliae’s flowers was investigated by using a convection solar dryer. Midilli-Kucuk model described well the drying curves’ trend. The effective moisture diffusivity values were obtained. The Arrhenius relation, with an activation energy value of 92.91 kJ.mol-1 expressed the temperature effect on the diffusion coefficient. Finally, the effect of drying these flowers at different temperatures on their quality was investigated. To assess the quality of the product after solar drying; the color, polyphenols content, antioxidant activity, and polyphenoloxydase and peroxydase activities were considered. 40 °C was the best drying temperature for the preservation of color and bioactive molecules with antioxidant property.