Bergamot essential oil

Bergamot essential oil

Bergamot essential oil is a cold-pressed essential oil produced by cells inside the rind of a bergamot orange fruit. It is a common top note in perfumes.

Bergamot essential oil is a major component of the original Eau de Cologne composed by Farina at the beginning of the 18th-century. The first record of bergamot oil as a fragrance ingredient is from 1714, found in the Farina Archive in Cologne. One hundred bergamot oranges will yield about three ounces (85 grams) of bergamot oil.[1] The scent of bergamot essential oil is similar to a sweet light orange peel oil with a floral note.[2]

"Earl Grey tea" is a type of black tea that contains bergamot essential oil as a flavouring.

Production

Bergamot fruits harvested for the production of essential oil.

The sfumatura or slow-folding process was the traditional technique for manually extracting the bergamot oil.[3]

The Macchina calabrese peeler, invented in 1840 by Nicola Barillà

Today the oil is extracted mechanically with machines called "peelers", these machines "scrape" the outside of the fruit under running water to get an emulsion channeled into centrifuges for separating the essence from the water.

Constituents

A clear liquid (sometimes there is a deposit consisting of waxes) in color from green to greenish yellow, bergamot essential oil consists for the most part (average 95%) of a volatile fraction and for the remaining (5%) of a non-volatile fraction (or residual). Chemically it is a highly complex mixture of many classes of organic substances, particularly for the volatile fraction terpenes, esters, alcohols and aldehydes, and for the non-volatile fraction, oxygenated heterocyclic compounds as coumarins and furanocoumarins.

Volatile fraction

The main compounds in the oil are limonene, linalyl acetate, linalool, γ-terpinene and β-pinene,[4] and in smaller quantities geranial and β-bisabolene.

Linalyl acetate and linalool are qualitatively the most important components of the bergamot oil.

Main volatile components of Bergamot essential oil[4]
Compound %
Limonene
  
 37.2%
Linalyl acetate
  
 30.1%
Linalool
  
 8.8%
γ-terpinene
  
 6.8%
β-pinene
  
 2.8%
minor compounds
  
 14.3%
green: terpenes; blue: esters; orange: alcohols; red: minor compounds

Non-volatile fraction

The main compounds are coumarins (citropten, 5-geranyloxy-7-methoxycoumarin) and furanocoumarins (bergapten, bergamottin).[5][6][7][8]

Main non-volatile components of Bergamot essential oil[8]
Compound conc. g/L
Bergamottin
  
 21.42
Citropten
  
 2.58
Bergapten
  
 2.37
5-Geranyloxy-7-methoxycoumarin
  
 1.12
orange: coumarins; green: furanocoumarins
Concentration in grams per liter of essential oil

Adulteration

The bergamot essential oil is particularly subject to adulteration being an essential oil produced in relatively small quantities. Generally adulteration is to "cut" the oil, i.e. adding distilled essences of poor quality and low cost, for example of bitter orange and bergamot mint and/or mixtures of terpenes, natural or synthetic, or "reconstruct" the essence from synthetic chemicals, coloring it with chlorophyll. Worldwide, each year, around three thousand tonnes of declared essence of bergamot are marketed, while the genuine essence of bergamot produced annually amounts to no more than one hundred tons.[9]

Comparison of bergamot oil obtained from the same raw plant material either by cold pressing or by hydrodistillation (Peratoner) using GC-MS analysis with enantiomeric column

Gas chromatography with columns having a chiral stationary phase allows to analyze mixtures of enantiomers. The analysis of the enantiomeric distribution of various compounds, such as linalyl acetate and linalool, allows the characterization of the bergamot oil according to the manufacturing process and allows for the detection of possible adulteration.[10][11][12][13]

The combined use of isotope ratio mass spectrometry and SNIF-NMR (Site-Specific Natural Isotope Fractionation-Nuclear Magnetic Resonance) allows to discover adulteration otherwise undetectable even allowing for the identification of the geographical origin of the essential oil.[14]

The GC-C-IRMS (Gas Chromatography-Combustion – Isotope Ratio Mass Spectrometer) technique, the most recently used, allows to obtain similar results.[15]

Reference analytical values

Analytical values take as reference for genuinity evalutation of bergamot essential oil by the Experimental Station for the Industry of the Essential oils and Citrus products, in Reggio Calabria, Italy.[16]

Chemical physical characteristics Min Max Unit
Refractive index (20 °C) 1.4640 1.4690 adim
Optical rotation (20 °C) +15.0 +34.0 °
Relative density (20 °C) 0.875 0.883 adim
Esters (expressed as linalyl acetate) 30 45 %
Evaporation residue 4.50 6.50 %
CD (spectrophotometric analysis) 0.75 1.20 adim
Main volatile fraction components Min Max Unit
Limonene 30 45 %
Linalool 3 15 %
Linalyl acetate 22 36 %
γ-terpinene 6 10 %
β-pinene 4.5 9 %
Δ3-carene trace 0.008 %
Terpinen-4-ol trace 0.06 %
Enantiomeric ratios of main chiral components Min Max Unit
Limonene ((+)-Limonene / (-)-Limonene) (97.4 / 2.6) (98.4 / 1.6) %
Linalool ((+)-Linalool / (-)-Linalool) (0.3 / 99.7) (0.7 / 99.3) %
Linalyl acetate ((+)-Linalyl acetate / (-)-Linalyl acetate) (0.3 / 99.7) (0.6 / 99.4) %
Non volatile residue components Min Max Unit
Bergapten 1800 3800 mg/Kg

Toxicology

Patch test

In several studies, application of some sources of bergamot oil directly to the skin via patch test was shown to have a concentration-dependent phototoxic effect of increasing redness after exposure to ultraviolet light (due to the chemical bergapten, and possibly also citropten, bergamottin, geranial, and neral).[17][18] This is a property shared by many other citrus fruits. Bergapten has also been implicated as a potassium channel blocker; in one case study, a patient who consumed four liters of Earl Grey tea per day suffered paresthesias, fasciculations and muscle cramps.[19]

Notes

  1. ↑ Brannt, William Theodore; Schaedler, Karl. A Practical Treatise on Animal and Vegetable Fats and Oils
  2. ↑ http://www.fragrantica.com/notes/Bergamot-75.html
  3. ↑ Angelo Di Giacomo e Biagio Mincione (1994). Gli Olii Essenziali Agrumari in Italia (in Italian). Reggio Calabria: Laruffa Editore.
  4. 1 2 Sawamura, Masayoshi; Onishi, Yuji; Ikemoto, Junko; Tu, Nguyen Thi Minh; Phi, Nguyen Thi Lan (2006). "Characteristic odour components of bergamot (Citrus bergamia Risso) essential oil". Flavour and Fragrance Journal 21 (4): 609–615. doi:10.1002/ffj.1604. ISSN 0882-5734.
  5. ↑ Benincasa, M.; Buiarelli, F.; Cartoni, G. P.; Coccioli, F. (1990). "Analysis of lemon and bergamot essential oils by HPLC with microbore columns". Chromatographia 30 (5–6): 271–276. doi:10.1007/BF02319706. ISSN 0009-5893.
  6. ↑ Mondello, Luigi; Stagno d'Alcontres, Ildefonsa; Del Duce, Rosa; Crispo, Francesco (1993). "On the genuineness of citrus essential oils. Part XL. The composition of the coumarins and psoralens of Calabrian bergamot essential oil (Citrus bergamia Risso)". Flavour and Fragrance Journal 8 (1): 17–24. doi:10.1002/ffj.2730080105. ISSN 0882-5734.
  7. ↑ Cavazza, A.; Bartle, K. D.; Dugo, P.; Mondello, L. (2001). "Analysis of oxygen heterocyclic compounds in citrus essential oils by capillary electrochromatography and comparison with HPLC". Chromatographia 53 (1–2): 57–62. doi:10.1007/BF02492428. ISSN 0009-5893.
  8. 1 2 Dugo, Paola; Piperno, Anna; Romeo, Roberto; Cambria, Maria; Russo, Marina; Carnovale, Caterina; Mondello, Luigi (2009). "Determination of Oxygen Heterocyclic Components in Citrus Products by HPLC with UV Detection". Journal of Agricultural and Food Chemistry 57 (15): 6543–6551. doi:10.1021/jf901209r. ISSN 0021-8561.
  9. ↑ (Italian) Tonio Licordari La riflessione Valorizzare ora questa risorsa sulla scia dell'onda... profumata Gazzetta del Sud Cronaca di Reggio 18-02-2010
  10. ↑ Mondello, Luigi; Verzera, Antonella; Previti, Piero; Crispo, Francesco; Dugo, Giovanni (1998). "Multidimensional Capillary GC−GC for the Analysis of Complex Samples. 5. Enantiomeric Distribution of Monoterpene Hydrocarbons, Monoterpene Alcohols, and Linalyl Acetate of Bergamot (Citrus bergamia Risso et Poiteau) Oils". Journal of Agricultural and Food Chemistry 46 (10): 4275–4282. doi:10.1021/jf980228u. ISSN 0021-8561.
  11. ↑ Eleni, Melliou; Antonios, Michaelakis; George, Koliopoulos; Alexios-Leandros, Skaltsounis; Prokopios, Magiatis (2009). "High Quality Bergamot Oil from Greece: Chemical Analysis Using Chiral Gas Chromatography and Larvicidal Activity against the West Nile Virus Vector". Molecules 14 (2): 839–849. doi:10.3390/molecules14020839. ISSN 1420-3049.
  12. ↑ Burfield, Tony. "The Adulteration of Essential Oils – and the Consequences to Aromatherapy & Natural Perfumery Practice.". Presented to the International Federation of Aromatherapists Annual AGM London Oct 11th 2003. Retrieved 16 June 2013.
  13. ↑ Cotroneo, Antonella; Stagno d'Alcontres, Ildefonsa; Trozzi, Alessandra (1992). "On the genuineness of citrus essential oils. Part XXXIV. Detection of added reconstituted bergamot oil in genuine bergamot essential oil by high resolution gas chromatography with chiral capillary columns". Flavour and Fragrance Journal 7 (1): 15–17. doi:10.1002/ffj.2730070104. ISSN 0882-5734.
  14. ↑ Hanneguelle, Sophie.; Thibault, Jean Noel.; Naulet, Norbert.; Martin, Gerard J. (1992). "Authentication of essential oils containing linalool and linalyl acetate by isotopic methods". Journal of Agricultural and Food Chemistry 40 (1): 81–87. doi:10.1021/jf00013a016. ISSN 0021-8561.
  15. ↑ Luisa Schipilliti, G. Dugo, L. Santi, P. Dugo and L. Mondello (2011). "Authentication of Bergamot Essential Oil by Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometer (GC-C-IRMS)". Journal of Essential Oil Research 23 (2): 60–71. doi:10.1080/10412905.2011.9700447.
  16. ↑ (Italian) (English) Francesco Gionfriddo e Domenico Castaldo (2004). "Ridefinizione dei parametri analico-composizionali dell'olio essenziale di bergamotto estratto a freddo / Ridefinition of analitycal compositional parameters for "cold pressed" bergamot essential oil". Essenze Derivati Agrumari (74): 151–152.
  17. ↑ Girard J, Unkovic J, Delahayes J, Lafille C (1979). "Phototoxicity of Bergamot oil. Comparison between humans and guinea pigs". Dermatologica (in French) 158 (4): 229–43. doi:10.1159/000250763. PMID 428611.
  18. ↑ Kejlova K, Jirova D, Bendova H, Kandarova H, Weidenhoffer Z, Kolarova H, Liebsch M (2007). "Phototoxicity of bergamot oil assessed by in vitro techniques in combination with human patch tests". Toxicology in Vitro 21 (7): 1298–1303. doi:10.1016/j.tiv.2007.05.016. PMID 17669618.
  19. ↑ Finsterer, J (2002). "Earl Grey tea intoxication". Lancet 359 (9316): 1484. doi:10.1016/S0140-6736(02)08436-2. PMID 11988248.

Bibliography

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