An Experimental Study of Different Drying Methods on the Quality and Quantity Essential Oil of Myrtus communis L. leaves

Myrtus communis L.is one of the most important aromatic and medicinal plants that used in the food, pharmaceutical and cosmetic industries. The effect of six drying methods (shade, Oven 40oC Oven 60oC, Microwave 700W, Vibro-spouted bed (VSB) 40oC) on yield and chemical composition of essential oil of M. communis leaves was investigated. The oils from fresh and dried leaves were isolated using hydrodistillation in a Clevenger apparatus and analyzed by gas chromatography-mass spectrometry (GC-MS).The highest essential oil yields were obtained by shade (1.87 %) followed by VSB 40oC (1.63 %), oven 40oC (1.35 %),VSB 60oC (1.23 %), microwave (1.05 %), oven 60oC (0.81 %) and fresh (0.47 %). Increasing the drying temperature significantly reduced the essential oil content of in VSB and oven methods. Forty-one components were identified in the oils of M. communis. The major constituents of the essential oil, -pinene (7.04-31.29 %), dl-limonen (14.98-21.58 %), and linalool (1.72-15.47 %), showed considerable variation regarding drying techniques. Tricyclene, as a new component, was only identified in VSB procedure (7.02 % and 8.07 %). -fenchylalcohol also found in VSB 60oC. Furthermore, in the microwave technique 3-cyclohexene-1-methanol (17.31 %) was found, while this component was not present in the other treatments. Therefore, these results showed yield and chemical composition of the essential oil from M. communis varied according to drying methods. Shade and VSB techniques could be considered as the two best drying techniques in term of essential oil yield and bioactive compounds contents. Moreover, VSB drying is desirable because of time saving.