Volatilomic analysis based on headspace–gas chromatography–mass spectrometry (HS-GC–MS) combined with chemometrics for the authentication of fennel (Foeniculum vulgare) essential oil

Fennel (Foeniculum vulgare) is a native plant from the Mediterranean area that has spread worldwide, including tropical Indonesia. As an important product for various industries, fennel essential oil is prone to adulteration to increase profit. In this study, we characterized the volatile profile of fennel essential oil from fennel grown in Indonesia using headspace–gas chromatography–mass spectrometry (HS–GC–MS) for simple and fast analysis and further applied this method, in combination with chemometrics, to detect the adulteration. The major constituents of essential oil extracted from Indonesian fresh fennel fruits were fenchone (39.61 ± 2.00%), estragole (17.47 ± 1.60%), limonene (14.21 ± 4.35%), and anethole (11.65 ± 1.75%). The commercial fennel oils had varied volatile profiles. The PCA model showed that some commercial samples had a similar volatile profile with pure fennel oil, indicating that the samples indeed contained fennel oil. On the other hand, adulterated fennel oils with carrier oil showed a very similar volatile profile to pure fennel oils, making it difficult to pinpoint the adulterated samples. In the PCA model, the adulterated fennel oils were distinguishable from the pure fennel oils and clustered in an area different from those of pure fennel oils. Thus, HS–GC–MS combined with chemometrics has been successfully applied to detect adulteration in fennel essential oils.