The effect of microwaves on constituents and antioxidant power of essential oils of Zataria multiflora and Syzygium aromaticum

Background: Hydrodistillation is a current method to extract plant essential oils which is time consuming. It has been proposed that use of microwaves instead of direct heat could decrease the time of distillation. In this study, the effect of microwaves on chemical profile and antioxidant activity of Zatariam multiflora and Syzygium aromaticum essential oils in comparison to current hydrodistillation method was evaluated. Materials and methods: In this study, Zataria multiflora and Syzygium aromaticum essential oils were extracted by hydrodistillation and microwave assisted hydrodistillation method. Chemical profile of essential oils were determined by GC MASS. Their antioxidant activity in inhibition of free radicals were evaluated by DPPH method. Results: Microwave decreased the amount of thymol and eugenol in Zataria multiflora and Syzygium aromaticum essential oils respectively. Also, the antioxidant activity of essential oils extracted by microwaves decreased in comparison to current hydrodistillation method. Conclusion: According to the results, it is necessary to evaluate the quality of essential oils before using microwaves to extract essential oils in the food, pharmaceutical and cosmetic industries. However, in order to confirm the effect of microwave waves on plant essential oils, study on more plant samples is essential.