Impact of various drying technologies for evaluation of drying kinetics, energy consumption, physical and bioactive properties of Rose flower.

The process after harvesting medicinal plants, such as drying, is very important in the production cycle of these plants. The study's objective is to evaluate the effect of different drying methods on some thermodynamic properties, qualitative and bioactive attributes, and yield of rose essential oil in form of a completely randomized design. The treatments of this study included drying in refractance window (RW), infrared (IR), and convective (CV) at three drying temperatures of 50, 60, and 70 °C, as well as fresh plants. The results showed that different drying methods and temperatures significantly affected the essential oil, thermodynamic, qualitative, bioactive, and yield characteristics. The lowest drying time, energy consumption, and the highest energy efficiency and rehydration ratio in the dried rose samples were related to the drying temperature of 70 °C in the RW method. The reduction of drying time by RW method compared to IR and CV methods was between 11.1-21.40 and 45.9-50%, respectively. The highest amount of antioxidant activity, total phenol, flavonoid and essential oil yield was observed in the RW drying method and at the drying temperature of 60 °C. This study showed that compared to other drying methods, the RW method showed a high quality in drying Rose flowers.