Production of thymol rich extracts from ajwain (Carum copticum L.) and thyme (Thymus vulgaris L.) using supercritical CO2

Supercritical fluid extraction is the most efficient technique to extract flavor and fragrance compounds. This study aims to obtain thymol rich extracts by supercritical fluid CO2-extraction (SFE) of Carton copticum L. (ajwain) and Thymus vulgaris L. (thyme). The yield, chemical constituents analyzed by gas chromatography-mass spectrometry and sensory characteristics of the extracts were compared with their volatile oil counterparts extracted by hydrodistillation (HD). The SFE extracts were obtained at a low temperature (40 degrees C) and two pressures (10.4 and 16.7 MPa). The yield of the ajwain and thyme extracts reached 2.78 +/- 0.04 and 1.28 +/- 0.15 % (w/w), respectively, at 16.7 MPa. The SFE successfully increased the thymol relative amount in the ajwain and thyme extracts by 1.7 and 2.49 fold compared with its level in the hydrodistilled essential oils, respectively. The extract obtained at high pressure exhibited the most valued sensory characteristics (spicy, pungent, aromatic/herbaceous, phenol-like and absence of burnt note).