Characterization of cold-pressed and processed bergamot oils by using GC-FID, GC-MS, GC-C-IRMS, enantio-GC, MDGC, HPLC and HPLC-MS-IT-TOF

Abstract

Numerous samples of Italian cold-pressed bergamot oils, representative of the industrial production of the last three seasons (2008/09, 2009/10 and 2010/11), as well as several samples of bergapten-free, concentrated and recovered oils, have been extensively investigated in the present study. The samples were analyzed to determine the composition of the volatile fraction, the oxygen heterocyclic compounds, the enantiomeric distribution of twelve volatile components and the isotopic ratios of selected volatiles. Differences from previous studies emerged. The recent improvement in cultural practices is confirmed by the increase of linalool and linalyl acetate, indicative of better quality of the essential oils. The seasonal variation of the enantiomeric excess of α-terpineol, characteristic of cold-pressed bergamot oils, is confirmed. Some oxygen heterocyclic compounds are here quantitatively determined for the first time. The presence of herniarin is confirmed in genuine samples through high-pressure liquid-chromatography–mass spectrometry–ion trap–time of flight (HPLC-MS-IT-TOF). The isotopic ratios herein reported, for all the samples analyzed, represent a useful tool for the evaluation of genuineness of cold-pressed and processed bergamot oils.

Keywords:

• C. bergamia essential oil composition
• enantiomeric distribution
• isotope ratios
• genuineness
• seasonal variation
• herniarin.

Acknowledgements

The authors acknowledge Dr. Maria Restuccia for her contribution during the analyses of the samples and gratefully acknowledge Shimadzu and Sigma-Aldrich/Supelco Corporations for their continuous support.