Description
A tree, 9 to 15 m (30 to 50 ft.) tall, having a rounded and conical
head, ovate glabrous leaves, and smooth, gray-brown bark. The
flowers are large, white, and fragrant. The fruits are large, lightlemon
or orange with a thin rind and grayish-yellow or pink flesh.
Historically and botanically, the origin of the grapefruit is uncertain
and appears to have developed from the Shaddok variety native
to the West Indies. The plant is cultivated in the United States
(Florida, California, Texas), East Asia, West Indies, Brazil, and
Nigeria. The Citrus decumana variety yields the largest fruits (up
to 10 kg). The parts used are the fruit and peel. Grapefruit has a
fresh, citrus-like odor and a taste reminiscent of sweet and bitter
orange to some degree.
Grapefruit essential oil is the volatile oil obtained by cold expression
of the fresh peels of the fruit. The oil is a yellow, sometimes
reddish liquid (often showing a flocculent separation of waxy
material) with a pleasant citrus-like odor and flavor.
Its main constituents include limonene (90%), 2 to 3% volatile
fraction containing oxygen compounds and sesquiterpenes, 7 to
8 % waxy fraction, C8 and C10 aldehydes, geraniol, cadinene, small
amounts of citral and dimethyl anthranilate, and acids. A terpeneless
oil can be prepared by vacuum distillation, yielding a more
soluble and more stable concentrated oil. However, a certain
amount of terpenes must be left in the oil to retain the characteristic
freshness of citrus flavor.
A lower grade of essential oil that does not have application in
flavor work is also obtained by steam distillation of the crushed
peels or even from seeds.
The derivatives are juice and extract. Naringin, a bitter, white,
crystalline glucoside, is found in the blossoms and the flavedo of
the fruits. Naringin yields rhamnose and naringenin (C15H12O5) on
hydrolysis. A naringin extract, prepared from the expressed peels,
is used in flavors.
Chemical Properties
Grapefruit oil is obtained by cold-pressing of the outer peels of the fruits of
Citrus x paradisi Macfad. (Rutaceae). It is a greenish-yellow liquid, with an
odor resembling that of sweet orange oil, but more herbaceous and bitter.
d2020 0.852–0.860; n20D 1.4740–1.4790; α20D +91 ° to +96 °; total carbonyl
content calculated as decanal of 0.28–2%; evaporation residue: max. 10.0%.
Usually, grapefruit oil contains more than 90% (+)-limonene (92–96%).
Constituents determining the typical sensory properties are present only in
low concentrations, for example, octanal (0.2–0.8%), decanal (0.1–0.6%),
and 0.01–0.8% nootkatone, which is primarily responsible for the characteristic
aroma of grapefruit oil. The sensory properties vary
with the grapefruit cultivar (e.g., white/pink grapefruits) used for the oil production.
The main producer of the oil is still the United States (Florida), although
the grapefruit cultivation declined drastically after the hurricanes in
2004/2005. Additional oil producers are Cuba, Israel, Argentina, Mexico,
Southern Africa, and so on. Worldwide production was estimated at
～2000 t/yr in 2001/2003.
Grapefruit oil is used mainly for flavoring fruit beverages. As with bergamot
oil, the use of cold-pressed grapefruit oil is restricted in perfume compositions
due to a content of furocoumarins.
Chemical Properties
Grapefruit oil is the volatile component obtained by expression of the fresh peels of the fruit It has a pleasant citrus-like odor and favor A low-grade oil is obtained by steam distillation of the crushed peels or even from seeds, but is not used in favor work In the United States, grapefruit oil is produced mainly in Florida and to a lesser extent in Texas and California.
Physical properties
Its color is yellow, sometimes reddish (often showing a focculent separation of waxy material) It is soluble in most fxed oils, often with opalescence or cloudiness It is slightly soluble in propylene glycol and insoluble in glycerin It may contain.
Occurrence
Found in the fresh peel of the fruit Citrus paradisi Macfayden (Fam. Rutaceae).
Definition
Extractives and their physically modified derivatives. Citrus paradisi, Citrus.
Preparation
By expression of the fresh peel of the fruit.
Essential oil composition
The main constituent of grapefruit oil expressed is limonene
