Effect of Different Drying Methods on Some Biochemical Properties of Iranian Ox-tongue (Echium amoenum Fisch. & Mey.)

Iranian ox-tongue (Echium amoenum Fisch. & Mey.) is an endemic Iranian medicinal plant belongs to Boraginaceae family. The violet-blue petals of this plant have been used in traditional medicine. Drying is one of the most critical and fundamental operations in the post-harvest processing of medicinal plants. This research was carried out in Islamic Azad University, Isfahan (Khorasgan) branch in 2015. The experiment was arranged based on completely randomized design with three repetitions. Drying methods are including sun and shade drying, oven-drying (45, 65 and 85∘C) and microwave drying (200, 300 and 400 W). Drying time of Iranian Ox-tongue petals and some biochemical properties such as total chlorophyll, the amount of carotenoids, anthocyanin content and total flavonoids were measured. The results showed that different drying methods had significant effects on drying time, chlorophyll, carotenoids, total flavonoid and anthocyanin contents of Iranian ox-tongue petals. The maximum and minimum drying times were measured in shade drying and microwave 400 W, respectively. The anthocyanin content gradually decreased with the increase of oven temperatures and microwave powers. Also shade drying method had the highest amount of total chlorophyll and carotenoids. Generally, regarding the biochemical composition, traditional shade drying is the optimum method for dying of Iranian ox-tongue petals.  According to this study, shade drying could be recommended in terms of qualitative characteristics of mentioned medicinal plant.