The major chemical constituents of bergamot oil are linalyl acetate, limonene, linalool, and γ-terpinene. The components chiefly responsible for its flavor are linalool, citral, and linalyl acetate. Other constituents include β-pinene, α-pinene, sabinene, caryophyllene, geranyl acetate, and geranial, as well as nonvolatile compounds, such as pigments, waxes, coumarins and psoralens.
| Constituent | Description | Percentage by weight |
|---|---|---|
| Limonene | Monoterpene hydrocarbon | 30–50% |
| Linalyl acetate | Monoterpene ester | 23–35% |
| γ-terpinene | Monoterpene hydrocarbon | 6–19% |
| Linalool | Monoterpene alcohol | 6–15% |
| β-pinene | Monoterpene hydrocarbon | 5–10% |
| All other components each less than 1% by weight |
(Table adapted from Calapai, G. et al. Assessment report on Citrus bergamia Risso et Poiteau, aetheroleum. European Union: European Medicines Agency Committee on Herbal Medicinal Products (HMPC). 2012.)
The oil’s composition depends on the method of extraction. Vacuum-distilled bergamot essential oil is psoralen-free, while cold-pressed bergamot oil contains phototoxic psoralens, notably bergapten (5-methoxypsoralen, or 5-MOP) and bergamottin (5-geranyloxypsoralen).[1][2]
The International Standards Organization (ISO) has established a technical standard for the composition of bergamot essential oil;[3] however, not all consumer samples of bergamot oil meet that standard.[4]