Influence of extraction procedure on the aroma composition of Thymus zygis L. and Mentha pulegium L.

The present work compares the results of two extraction procedures (Clevenger distillation and compressed CO2 extraction) on the yield and composition of the aromatic extracts. A RSM was applied in order to determine the best extraction conditions by compressed CO2. The matrix was established for the following ranges: time 60-180 min, temperature 40-50 degrees C and pressure 9-20 MPa. All the extracts were analysed by GC and GCMS. The results showed that the yields are generally higher for compressed CO2: 2.1% for Mentha pulegium and about 3% for Thymus, compared to a value of 0.9% and 1% by distillation. The main compound found in M. pulegium is pulegeone. In T. zygis the main compounds are thymol, geraniol and geranyl acetate.