Effects of different drying methods on the chemical compounds profile and antibacterial efficacy of peppermint essential oil against Staphylococcus aureus bacteria in vitro conditions

 Peppermint is one of the valuable medicinal plants with strong anti-microbial and anti-oxidant properties, which has various applications in the food industry.

 Fresh peppermint leaves were processed as a single layer by different drying methods (solar, sun and shade). Then, the effect of different drying methods on the quality and quantity of essential oil compounds was evaluated by GC-MS. Also, the antibacterial efficiency of the noted essential oil against Staphylococcus aureus bacteria was studied by disk diffusion method.

 The results showed that the most important chemical compounds in peppermint essential oil include menthone, menthol, isomenthol, mentofuran, polygon and piperitone. The highest amount of bacterial inhibition zone (IZ) was observed in the case of essential oil extracted from peppermint leaves dried by solar method (IZ=55 mm).

In general, the drying method is one of the main stages of medicinal plants processing, which has a significant effect on the bioactive compounds (extracts and essential oils) of medicinal plants. Therefore, it is necessary to use the suitable drying method.