Grapefruit, expressed oil

Restrictions for furocoumarin containing essential oils have been recommended for Angelica root oil, Bergamot oil expressed, Bitter orange oil expressed, Cumin oil, Grapefruit oil expressed, Lemon oil cold pressed, Lime oil expressed, Rue oil. 

SYNS GRAPEFRUIT OIL, coldptessed GRAPEFRUIT OIL, expressed OIL OF GRAPEFRUIT OIL OF SHADDOCK... 

Grapefruit Oil, Coldpressed, occurs as a yellow, sometimes red, liquid that often shows a flocculent separation of waxy material. It is the oil obtained by expression from the fresh peel of the grapefruit Citrus paradisi Macfayden (Citrus decu-mana L.) (Fam. Rutaceae). It is soluble in most fixed oils and in mineral oil, often with opalescence or cloudiness. It is slightly soluble in propylene glycol and insoluble in glycerin. It may contain a suitable antioxidant. 

Common/vernacular names Expressed grapefruit oil, cold-pressed grapefruit oil, and shaddock oil. 

SUMMARY In essential oils, most constituents are terpenes and terpenoid molecules. The method of extraction can influence the terpene content. In citrus oils extracted by expression (squeezing or pressing the plant material), the terpenes present are similar to those found in the living plant tissue for example, orange, lemon, mandarin and grapefruit essential oils may be made up of up to 90% of the monoterpene limonene. When extraction is by steam distillation the action of the hot water and steam on thermolabile (heat-sensitive) molecules present in the plant is responsible for the formation of the bulk of the terpene content. Solvent extraction often produces absolutes that are very low in terpenes or do not contain them at all, when compared to a distillation of the same material, for example as found in lavender and rose products. 

Oil of grapefruit (Citrus x paradisi Macfad.), obtained by expression... 

ISO standard 3053 shows character and data for this oil. Pure oils possess as marker the compound nootkatone from traces up to 0.8%, depending on the fruit status. This compound is used for blending, together with n-octanal, w-nonanal, n-decanal, and synthetic citral. Adulteration is performed by orange terpenes and distilled grapefruit residues from expression and limonene—80°. Detection must be done exclusively by multidimensional enantiomeric separation. Dugo and Mondello (2011) published the following chiral data (/ ) (-)-a-pinene (0.3%-0.8%) (5)-(+)-a-pinene (99.2% 99.7%) (/ )-(+) P pinene (62.0% 76.8%) (5) ( ) p-pinene (23.2%-38.0%) (/ )-(+)-sabinene (98.4%-98.5%) (5)-(-)-sabinene (1.5%-1.6%) (5)-(-)-limonene (0.5%-0.6%) (/ )-(+)-limonene... 

The phototoxicity of certain substituted coumarins is well documented (see bergamot). Expressed lime oil contains more of such compounds than the other citrus oils (e.g., bergamot and grapefruit) and has been reported to be phototoxic to humans. 

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