Impact of Drying Methods on Essential Oil Composition of Ocimum americanum L. From Kumaun Himalayas

The present study was aimed to investigate the effect of drying on the essential oil composition and oil content of Ocimum americanum L. For the study, the aerial parts of the plant were collected from Ranikhet, district Almora and dried using different drying methods until constant weight, i.e., sun-drying (26 degrees C +/- 5 degrees C), shade-drying (20 degrees C +/- 5 degrees C) and oven-drying (at 35 degrees C, 45 degrees C and 55 degrees C). Fresh and dried samples were hydrodistilled using Clevenger apparatus and the essential oil obtained was analyzed by GC and GC/MS. Essential oil content was found to be the highest for sun dried (0.7 %) followed by oven dried at 55 degrees C (0.3 %), shade dried (0.2 %), oven dried at 35 degrees C (0.2 %), oven dried at 45 degrees C (0.1 %) and fresh sample (0.1 %). 1,8-Cineole (9.14-23.67 %), methyl chavicol (5.70-16.34 %), beta-bisabolene (7.78-29.23 %) and (Z)-alpha-bisabolene (2.32-17.49 %) were the common major constituents of all the oils under different drying methods. The essential oil composition and oil yield were greatly affected by drying methods. Sun drying could be used as the most prominent drying method for O. americanum L. A significant amount of camphor (38.34 %) and highest essential oil content was present exclusively in the essential oil of sun dried material.