Discrimination of fennel chemotypes applying IR and Raman spectroscopy: discovery of a new γ-asarone chemotype

J Agric Food Chem. 2014 Apr 23;62(16):3537-47. doi: 10.1021/jf405752x. Epub 2014 Apr 14.


Various vibrational spectroscopy methods have been applied to classify different fennel chemotypes according to their individual profile of volatile substances. Intact fennel fruits of different chemotypes could be successfully discriminated by attenuated total reflectance Fourier transform infrared (ATR-FTIR) and near infrared (NIR) spectroscopy. Solvent extracts (CCl4) of the considered fennel fruits showed characteristic fingerprints with marker bands related to the individual volatile components (trans-anethole, fenchone, estragole, piperitenone oxide, γ-asarone, limonene) for ATR-FTIR and FT-Raman spectroscopy. Especially νC═C and νC═O absorption bands contribute to the different spectral profiles. On the basis of hierarchical cluster analysis, the considered fennel accessions were classified according to gas chromatographic (GC) and vibrational spectroscopic data. Furthermore, even a discrimination of "sweet" and "bitter" fennel fruits, both belonging to the trans-anethole chemotype, could be successfully performed. All vibrational spectroscopical techniques used in this study are rapid and easy to apply. Hence, they allow different fennel chemotypes to be reliably distinguished and can also be used for on-site measurement in free nature.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allylbenzene Derivatives
  • Anisoles / chemistry*
  • Discriminant Analysis
  • Foeniculum / chemistry*
  • Molecular Structure
  • Plant Extracts / chemistry*
  • Spectroscopy, Near-Infrared / methods*
  • Spectrum Analysis, Raman / methods*


  • Allylbenzene Derivatives
  • Anisoles
  • Plant Extracts
  • asarone