Development and optimization of microwave-assisted extraction of Satureja bachtiarica Bunge. essential oil using response surface methodology and its comparison with traditional method

Essential oils are one of the most secondary metabolites in therapeutic herbs, rich in oxygenated compounds [1]. The proficiencies of traditional hydro-distillation (THD) and microwave-assisted steam hydro-diffusion (MSHD) techniques in extraction of Bakhtiari savory oil were evaluated. In order to obtain the golden yield and total phenol (TPC) in MSHD method, three factors were examined at 5 levels by applying central composite design under RSM technique: extraction time (15, 25, 35, 45, 55 min), microwave power (200, 400, 600, 800, 1000 W) and water volume to plant ratio (W/P) (0, 0.5, 1.5, 2.5, 3 ml/g) [2, 3] .The results of RSM in THD method showed, extraction time and (W/P) separately affected on yield and TPC without interaction.The best yield was 1.64 V/W% that collected at conditions [54.16 min, 872.42 W, 2.09 ml/g for extraction time, microwave power and (W/P)]. By using folin-ciocalteu method, the maximum of TPC was 344.07 mgGAE/g that was obtained at points [19.7 min, 1000 W, 3 ml/g for time, power and (W/P)] in MSHD technique. The highest amount of oxygenated fraction (63.24 ± 0.442%) were produced in the microwave method. The MSHD method is the economic technique for green extraction of essential oil from pharmaceutical and fragrant herbs [4,5].