Bergamot essential oil is a cold-pressed essential oil produced by cells inside the rind of a bergamot orange fruit. It is a common flavoring and top note in perfumes. The scent of bergamot essential oil is similar to a sweet light orange peel oil with a floral note. [1]
The sfumatura or slow-folding process was the traditional technique for manually extracting the bergamot oil. [2] By more modern methods, the oil is extracted mechanically with machines called peelers, which scrape the outside of the fruit under running water to get an emulsion channeled into centrifuges for separating the essence from the water. The rinds of 100 bergamot oranges yield about 3 ounces (85 g) of bergamot oil. [3]
Bergamot essential oil has been used in cosmetics, aromatherapy, and as a flavoring in food and beverages. [4] Its citrus scent makes it a natural flavoring and deodorizing agent. [4] The volatile oils of the bergamot orange are described as flavoring agents in the USP Food Chemicals Codex and are generally recognized as safe for human consumption by the Food and Drug Administration. [5] For example, Earl Grey tea is a type of black tea that may contain bergamot essential oil as a flavoring agent. [4]
Historically, bergamot essential oil was an ingredient in Eau de Cologne, a perfume originally concocted by Johann Maria Farina at the beginning of the 18th century. [6] The first record of bergamot oil used as a fragrance in perfume is from 1714, found in the Farina Archive in Cologne. [7]
A clear liquid (sometimes there is a deposit consisting of waxes) in color from green to greenish yellow, bergamot essential oil consists of a volatile fraction (average 95%) and a non-volatile fraction (5% or residual). Chemically, it is a complex mixture of many classes of organic substances, particularly in the volatile fraction, including terpenes, esters, alcohols and aldehydes, and for the non-volatile fraction, oxygenated heterocyclic compounds as coumarins and furanocoumarins. [8]
The main compounds in the oil are limonene, linalyl acetate, linalool, γ-terpinene and β-pinene, and in smaller quantities geranial and β-bisabolene. [8]
The main non-volatile compounds are coumarins (citropten, 5-geranyloxy-7-methoxycoumarin) and furanocoumarins (bergapten, bergamottin). [9] [10]
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. [11]
Natural source analysis based on the Carbon-14 method can identify adulterated essences by detecting synthetic chemicals manufactured from petroleum that are used to mimic the chemical profile of bergamot oil and other essential oils.[ citation needed ]
Gas chromatography with columns having a chiral stationary phase allows analyzing 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. [12] [13] [14] [15]
The combined use of isotope ratio mass spectrometry and SNIF-NMR (Site-Specific Natural Isotope Fractionation-Nuclear Magnetic Resonance) allows discovering adulteration otherwise undetectable even allowing for the identification of the geographical origin of the essential oil. [16]
The GC-C-IRMS (Gas Chromatography-Combustion – Isotope Ratio Mass Spectrometer) technique, the most recently used, allows obtaining similar results. [17]
Analytical values take as reference for genuinity evaluation of bergamot essential oil by the Experimental Station for the Industry of the Essential oils and Citrus products , in Reggio Calabria, Italy. [18]
| Chemical physical characteristics | Min | Max | Unit |
|---|---|---|---|
| Refractive index at 20 °C (68 °F) | 1.4640 | 1.4690 | adim |
| Optical rotation at 20 °C (68 °F) | +15.0 | +34.0 | ° |
| Relative density at 20 °C (68 °F) | 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 |
The phototoxic effects of bergamot essential oil have been known for more than a century. In 1925, Rosenthal coined the term "Berloque dermatitis" [19] (from the French word "breloque" meaning trinket or charm) to describe the pendant-like streaks of pigmentation observed on the neck, face, and arms of patients. [20] [21] He was unaware that, in 1916, Freund had correctly observed that these pigmentation effects were due to sun exposure after the use of Eau de Cologne, a perfume infused with bergamot oil. [22]
Use of bergamot aromatherapy oil, followed by exposure to ultraviolet light (either sunlight or a tanning bed), has been reported to cause phytophotodermatitis, [23] a serious skin inflammation indicated by painful erythema and bullae on exposed areas of the skin. In one case, six drops of bergamot aromatherapy oil in a bath followed by 20–30 minutes exposure of ultraviolet light from a tanning bed caused a severe burn-like reaction. [24]
Bergamot essential oil contains a significant amount of bergapten, a phototoxic substance that gets its name from the bergamot orange. Bergapten, a linear furanocoumarin derived from psoralen, is often found in plants associated with phytophotodermatitis. [21] Note that bergamot essential oil has a higher concentration of bergapten (3000–3600 mg/kg) than any other Citrus-based essential oil. [25]
When bergamot essential oil is applied directly to the skin via a patch test, followed by exposure to ultraviolet light, a concentration-dependent phototoxic effect is observed. [26] [27] However, if the oil is twice rectified (and therefore bergapten-free), no phototoxic response is observed. [28]
The International Fragrance Association (IFRA) restricts the use of bergamot essential oil due to its phototoxic effects. Specifically, IFRA recommends that leave-on skin products be limited to 0.4% bergamot oil, [4] which is more restrictive than any other Citrus-based essential oil. [5]
Although generally recognized as safe for human consumption, bergamot essential oil contains a significant amount of bergamottin, one of two furanocoumarins believed to be responsible for a number of grapefruit–drug interactions. [29] [30] In one case study, a patient who consumed four liters of Earl Grey tea per day suffered paresthesias, fasciculations and muscle cramps. [31]
Perfume is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent. Perfumes can be defined as substances that emit and diffuse a pleasant and fragrant odor. They consist of manmade mixtures of aromatic chemicals and essential oils. The 1939 Nobel Laureate for Chemistry, Leopold Ružička stated in 1945 that "right from the earliest days of scientific chemistry up to the present time, perfumes have substantially contributed to the development of organic chemistry as regards methods, systematic classification, and theory."
Citrus hystrix, called the kaffir lime or makrut lime, is a citrus fruit native to tropical Southeast Asia.
An essential oil is a concentrated hydrophobic liquid containing volatile chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the oil of the plant from which they were extracted, such as oil of clove. An essential oil is essential in the sense that it contains the essence of the plant's fragrance—the characteristic fragrance of the plant from which it is derived. The term "essential" used here does not mean indispensable or usable by the human body, as with the terms essential amino acid or essential fatty acid, which are so called because they are nutritionally required by a living organism.
Lavender oil is an essential oil obtained by distillation from the flower spikes of certain species of lavender. There are over 400 types of lavender worldwide with different scents and qualities. Two forms of lavender oil are distinguished, lavender flower oil, a colorless oil, insoluble in water, having a density of 0.885 g/mL; and lavender spike oil, a distillate from the herb Lavandula latifolia, having a density of 0.905 g/mL. Like all essential oils, it is not a pure compound; it is a complex mixture of phytochemicals, including linalool and linalyl acetate.
Linalool refers to two enantiomers of a naturally occurring terpene alcohol found in many flowers and spice plants. Linalool has multiple commercial applications, the majority of which are based on its pleasant scent. A colorless oil, linalool is classified as an acyclic monoterpenoid. In plants, it is a metabolite, a volatile oil component, an antimicrobial agent, and an aroma compound. Linalool has uses in manufacturing of soaps, fragrances, food additives as flavors, household products, and insecticides. Esters of linalool are referred to as linalyl, e.g. linalyl pyrophosphate, an isomer of geranyl pyrophosphate.
Citrus bergamia, the bergamot orange, is a fragrant citrus fruit the size of an orange, with a yellow or green color similar to a lime, depending on ripeness.
Fragrance oils, also known as aroma oils, aromatic oils, and flavor oils, are blended synthetic aroma compounds or natural essential oils that are diluted with a carrier like propylene glycol, vegetable oil, or mineral oil.
Phototoxicity, also called photoirritation, is a chemically induced skin irritation, requiring light, that does not involve the immune system. It is a type of photosensitivity.
Camphene is a bicyclic organic compound. It is one of the most pervasive monoterpenes. As with other terpenes, it is insoluble in water, flammable, colorless, and has a pungent smell. It is a minor constituent of many essential oils such as turpentine, cypress oil, camphor oil, citronella oil, neroli, ginger oil, valerian, and mango. It is produced industrially by isomerization of the more common alpha-pinene using a solid acid catalyst such as titanium dioxide.
The terpinenes are a group of isomeric hydrocarbons that are classified as monoterpenes. They each have the same molecular formula and carbon framework, but they differ in the position of carbon-carbon double bonds. α-Terpinene has been isolated from cardamom and marjoram oils, and from other natural sources. β-Terpinene has no known natural source but has been prepared from sabinene. γ-Terpinene and δ-terpinene have been isolated from a variety of plant sources. They are all colorless liquids with a turpentine-like odor.
Methyl anthranilate, also known as MA, methyl 2-aminobenzoate, or carbomethoxyaniline, is an ester of anthranilic acid. Its chemical formula is C8H9NO2. It has a strong and fruity grape smell, and one of its key uses is as a flavoring agent.
Phytophotodermatitis, also known as berloque dermatitis or margarita photodermatitis, is a cutaneous phototoxic inflammatory reaction resulting from contact with a light-sensitizing botanical agent followed by exposure to ultraviolet light. Symptoms include erythema, edema, blisters, and delayed hyperpigmentation. Heat and moisture tend to exacerbate the reaction.
Linalyl acetate is an organic compound, the acetate ester of linalool and a phytochemical found in many flowers and spice plants. It is one of the principal components of the essential oils of bergamot and lavender. It often occurs together with linalool and is a widely used fragrance.
Bergapten (5-methoxypsoralen) is a naturally-occurring organic chemical compound produced by numerous plant species, especially from the carrot family Apiaceae and the citrus family Rutaceae. For example, bergapten has been extracted from 24 species of the genus Heracleum in the family Apiaceae. In the family Rutaceae, various Citrus species contain significant amounts of bergapten, especially the bergamot orange, the micrantha, and certain varieties of lime and bitter orange.
Aromatherapy is based on the use of aromatic materials, including essential oils and other aroma compounds, with claims for improving psychological well-being. It is offered as a complementary therapy or as a form of alternative medicine. Fragrances used in aromatherapy are not approved as prescription drugs in the United States.
The micrantha is a wild citrus from the papeda group, native to southern Philippines, particularly islands of Cebu and Bohol. Two varieties are recognized: small-flowered papeda, locally known as biasong, and small-fruited papeda or samuyao.
5-Geranyloxy-7-methoxycoumarin is a natural coumarin with the molecular formula C20H24O4. It is found in the essential oils of citrus such as bergamot.
Melitidin is a flavanone glycoside. Melitidin was discovered in bergamot orange juice and exhibits statin-like properties so the juice seems to have hypolipidemic activity.
Brutieridin is a flavanone glycoside. Brutieridin was discovered in bergamot orange juice and exhibits statin-like properties as well as an anticholesterolaemic effect. As a result, the juice seems to have hypolipidemic (lipid-lowering) activity.