10.5937/ratpov51-5077 = Effect of drying methods on essential oil yield, total phenol content and antioxidant capacity of peppermint and dill

Abstract

The present study aimed to estimate the effects of different drying methods on appropriate drying time, essential oil yield, total phenol content and antioxidant capacity of Anethum graveolens L. and Mentha piperita L. Factorial experiment was conducted in completely randomized design at research field and laboratory of agricultural campus of the University of Guilan during 2011-2012. Treatments were: two levels of plant type (peppermint and dill) and four levels of drying methods (oven drying at 60°C and 75°C, drying at natural shade and drying exposed to sunlight). Results indicated that different drying methods had significant effect on all observed characteristics. In this experiment increasing oven temperature lead to reduction of essential oil yield. Minimum and maximum essential oil were obtained when dill and peppermint were oven dried at 75° C (20.11 ml m-2 ) and dried in shading (28.44 ml m-2 ), respectively. Oven drying at 75° C reduced antioxidant capacity of dill while shade-drying increased antioxidant capacity of peppermint. However drying at 60° C may be an appropriate temperature for drying peppermint and dill plant material, due to a significant reduction of drying time with no adverse effects on the essential oil yields.