Quantification of Anethole in Fennel and Anise Essential Oils using Gas Chromatography and 1H-NMR-Spectroscopy

Abstract

Nine essential oils from fennel (seeds and herbs) and anise (seeds) from different origins were analysed for density, refractive index and for a complete composition through GC-MS and 1H-NMR-spectroscopy. Anethole was the main compound identified in fennel and anise essential oils. Anethole content varied between 30 – 90% in fennel oils and between 80 – 99% in anise oils; anethole is often used as flavouring substance in foods with a good antimicrobial activity also. A positive correlation was found between anethole content determined by GC-MS and 1H-NMR (r = 0.8567 for fennel oils and r = 0.6986 for anise oils). The results showed different levels of anethole in oils (values ranged between 30.66 % and 99.24 %). Electronic nose was a very good and rapid method for discrimination of essential oils based on PCA (Principal Component Analysis) with discrimination index above 90 for both essential oils.