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.
