Effect of Drying Method and Storage Days on Essential Oil Yield and Quality of Rue (Ruta Chalepensis) leaves

The genus Rue (Ruta chalepensis) is an aromatic medicinal plant used in the folk as an herbal remedy medicine for the treatment of a variety of disorders in Ethiopia. Information about the effects of drying methods and storage days on essential oil physical properties is limited. The fresh leaf of rue was collected from the Wondo Genet Agriculture research center and was subjected to sun and shade drying methods and four storage days (0,5,10, and 15) days for each day's moisture content and essential oil extraction using hydro distillation. The obtained essential oils were analyzed for physical properties (specific gravity and refractive index). The highest value of moisture content in percent was recorded at 0-day storage days with the value of 73.533 and the lowest one was recorded at 15-day sundry with the value of 8.400. The highest and lowest value of essential oil content in volume by weight in percent was 0.673 and 0.174 at 0 day and 10-day sun, respectively. The highest and lowest value of essential oil content weight by weight in percent was 0.996 and 0.287 at 0 day and 15-day sun, respectively. The results showed that the rue dried under shade had a higher level of moisture content, essential oil content, volume by weight and weight by weight, specific gravity, and refractive index compared to the rue leaf dried under sun-drying methods. In the case of storage days in all parameters except refractive index and specific gravity, the rue fresh leaf (0 days) was higher in moisture content and essential oil contents compared to others storage days. This study provides evidence that drying herbs for different storage days and different drying methods affect the essential oil content and physical properties of essential oil.