Investigation of optimum conditions for obtain essential oils from mint (Mentha spicata)

Medical and aromatic herbs and essential oils obtained from these herbs are used for various purposes, especially in scientific and commercial areas. In recent years, interest in natural products has led to an increase in demand for essential oils from herbs. In this study, it was aimed to investigate optimum conditions for drying and distillation processes for obtain essential oils from mint (Mentha spicata) leaves. For this reason, the effect of different drying technique (shade-drying, oven-drying at 35°C and 50°C) on moisture content, moisture ratio, drying rate and drying time, effective diffusion coefficient and activation energy of mint leaves were investigated. In addition, six different thin layer drying models (Page, Newton, Diffusion approach, Henderson and Pabis, Modified Henderson and Pabis, Midilli et al.) and artificial neural networks (Three-layer forward feed backward propagation network structure) were used to determine the drying kinetics of the shade-dried and oven-dried (35°C and 50°C) mint samples. Essential oils from the mint samples dried by different methods was obtained by hydrodistillation method using clevenger apparatus. GC/MS analysis was performed to determine the content and composition of mint essential oils. As a result of the analyzes, the highest carvone amount and essential oil ratio were obtained from the shade-dried samples, the experimental design was made only on the shade-dried samples. The essential oils amount and carvone ratio of the shade-dried samples were modeled using the response surface methodology (RSM) with central composite design in the Design Expert-10 (trial) software.