Subcritical water extraction of Thymol from Ajowan seeds by Taguchi experimental design

In this study، the essential oil of Ajowan seeds was extracted by subcritical water extraction process (SWE). Thymol as the main component of the extracted essential oils was quantified by GC and GC–mass spectrometry. This extraction has been performed using Taguchi design approach under following conditions: temperature (100، 150 and 175 ◦C)، mean particles size (0. 25، 0. 5 and 1 mm) and water flow rates (1. 0، 2. 0 and 4. 0 mL/min). The optimum conditions as obtained from signal-to-noise ratio analysis in terms of amount Thymol were as follows: 175 ◦C، 0. 25 mm and 2. 0 mL/min. The SWE efficiency at optimized conditions was compared with the other conventional methods such as hydrodistillation and Soxhlet extraction. The SWE results showed a higher amount of Thymol (25. 248 mg/g dried sample) than hydrodistillation (13. 992) and Soxhlet extraction (7. 209).