Effect of drying temperature on essential oil content and composition of sweet wormwood (Artemisia annua) growing wild in Iran.

Studies were conducted to show the effect of different temperatures in the drying process on the amount and quality of essential oils of sweet wormwood (Artemisia annua L.). The sweet wormwood aerial parts were harvested in full blooming time from an area around the Siahkal city in north of Iran in September 2005. In order to complete drying, the aerial parts were placed at shade (room temperature) and in oven at 35, 45, 55 and 65 degrees C temperatures. The aerial parts essential oil was extracted by hydrodistillation in a Clevenger apparatus and analyzed by GC/MS. Results showed that higher drying temperatures decreased the essential oil content, from 1.12% (room temperature) 0.88% (35 degrees C), 0.55% (45 degrees C) to 0.50% (55 degrees C) and 0.37% (65 degrees C). Thirty-five components were determined in essential oils, which were mostly monoterpenes. The drying temperatures had a significant effect on the essential oils composition and proportion of the various components, as when the temperature increased, the monoterpenes content gradually decreased and vice versa for sesquiterpenes. The major components were artemisia ketone and 1, 8 cineol for room and 45 degrees C; artemisia ketone, 1, 8 cineol and camphor for 35 and 55 degrees C and beta-caryophyllene and germacrene D for 65 degrees C temperatures.