Microwave-assisted hydrodistillation (MAHD) has recently been attended for the extraction of essential oils from medicinal plants/herbs. In this study, MAHD was investigated for the extraction of essential oils from two genotypes of savory (Satureja hortensis, so-called summer savory, and Satureja montana, socalled winter savory). Three levels of microwave power (220, 440 and 660 W) were selected for the extraction. MAHD resulted in a shorter extraction time compared to that in HD. Total extraction times at 660 W microwave power was 180 min for S. hortensis and 90 min for S. montana. The extraction yield obtained by MAHD was almost equal to that obtained by HD (3.1%, w/w, for S. hortensis and 0.7% for S. Montana). Extraction was more efficient at higher power levels.Keywords: essential oils, microwave-assisted hydrodistillation, Satureja hortensis, Satureja montana, savory *To whom correspondence should be addressed. Email: krezaee@ut.ac.ir IntroductionThe use of herbs and plants in food industry has a long history. The diversity among the components of the plants has resulted in their use in many applications including in flavors and fragrances as well as in medicine. Essential oils are among the secondary metabolites produced within the various organs of medicinal herbs/plants. They are complex mixtures of volatile compounds such as terpenes (mostly monoterpenes and sesquiterpenes), phenolics and alcohols . The conventional method for the extraction of essential oils is hydrodistillation (HD), in which the essential oils are evaporated by heating a mixture of water and plant materials followed by the liquefaction of the vapors in a condenser. However, this method suffers from several disadvantages including losses in the volatile compounds, long extraction time and degradation of some components through thermal and/or hydrolytic effects (Khajeh et al., 2004;. Because of these shortcomings, newer approaches such as microwave-assisted extraction (MAE,) with or without the use of a solvent, have been developed. MAE, for example, has been applied for the extraction of cocaine and benzoylecgonine from coca leaves by using both polar and nonpolar solvents (Brachet et al., 2002). MAE has also been investigated for the extraction of essential oils from several herbs including artemisia (Hao et al., 2002), caraway seeds (Chemat et al., 2005), orange peel (Ferhat et al., 2006), lavender (Chemat et al., 2006, and cardamom (Lucchesi et al., 2007). Another extraction method in this area is microwave assisted hydrodistillation (MAHD,) which is an advanced hydrodistillation method based on the use of a microwave oven. This technique has recently been investigated in the extraction of volatile secondary metabolites from Lippia Alba (Stashenko et al., 2004a) and Xylopia aromatica (Stashenko et al., 2004b). The efficiency of MAHD is strongly dependent on the dielectric constant of water and the matrix (Brachet et al., 2002). MAHD causes the rapid delivery of energy to the total volume of solvent/ sample leading to a rapid rise ...

Antibacterial properties and chemical characterization of the essential oils from summer savory (Satureja hortensis) extracted by microwave-assisted hydrodistillation (MAHD) were compared with those of the essential oils extracted using the traditional hydrodistillation (HD) method. While MAHD at 660 W required half as much time as HD needed, similar antibacterial efficacies were found from the essential oils obtained by the two extraction methods on two food pathogens (Staphylococcus aureus, a gram positive bacterium, and Escherchia coli, a gram negative bacterium). Also, as it was the case with the essential oils extracted by HD, that of MAHD indicated greater influence on S. aureus than on E. coli. The compositions of the extracted essential oils were also studied using GC-MS analysis. The same components with negligible differences in their quantities were found in the extracted essential oils using the two methods outlined above. Overall, to reduce the extraction time, MAHD can be applied at higher microwave levels without any compromise in the antibacterial properties of the essential oils extracted.