grapefruit

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Grapefruit
Grapefruit, hybrid citrus.
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Sapindales
Family:	Rutaceae
Genus:	Citrus
Species:	C. × paradisi
Binomial name
Citrus × paradisi Macfad.

The grapefruit is a subtropical citrus tree known for its bitter fruit, an 18th-century hybrid first bred in Jamaica.^[1] When found in Barbados it was named the "forbidden fruit";^[2] it is also called the "shaddock", after its creator.

These evergreen trees are usually found at around 5–6 metres (16–20 ft) tall, although they can reach 13–15 metres (43–49 ft). The leaves are dark green, long (up to 150 mm, or 6 inches) and thin. It produces 5 cm (2 in) white four-petaled flowers. The fruit is yellow-orange skinned and largely oblate, and ranges in diameter from 10–15 cm. The flesh is segmented and acidic, varying in color depending on the cultivars, which include white, pink and red pulps of varying sweetness. The 1929 US Ruby Red (of the Redblush variety) has the first grapefruit patent.^[3]

The fruit has only become popular from the late 19th century; before that it was only grown as an ornamental plant. The US quickly became a major producer of the fruit, with orchards in Florida, Texas, Arizona, and California. In Spanish, the fruit is known as toronja or pomelo.

History

One ancestor was the Jamaican sweet orange (Citrus sinensis); the other was the Indonesian pomelo (Citrus maxima). Captain Shaddock brought pumelo seeds to Jamaica and bred the first fruit.^[1]

The hybrid fruit was in 1750 documented by the Rev. Griffith Hughes describing specimens from Barbados.^[4] Currently, the grapefruit is said to be one of the "Seven Wonders of Barbados."^[5] It was brought to Florida by Count Odette Philippe in 1823 in what is now known as Safety Harbor. Further crosses have produced the tangelo (1905), the minneola (1931), and the sweetie (1984). The sweetie has very small genetic and other differences from pomelo.

The grapefruit was known as the shaddock or shattuck until the 1800s. Its current name alludes to clusters of the fruit on the tree, which often appear similar to grapes.^[6] Botanically, it was not distinguished from the pomelo until the 1830s, when it was given the name Citrus paradisi. Its true origins were not determined until the 1940s. This led to the official name being altered to Citrus × paradisi.^[7][8]

The 1929 Ruby Red patent was associated with real commercial success, which came after the discovery of a red grapefruit growing on a pink variety. Only with the introduction of the Ruby Red did the grapefruit transform into a real agricultural success. The Red grapefruit, starting with the Ruby Red, has even become a symbolic fruit of Texas, where white "inferior" grapefruit were eliminated and only red grapefruit were grown for decades. Using radiation to trigger mutations, new varieties were developed to retain the red tones which typically faded to pink,^[9] the Rio Red variety is the current (2007) Texas grapefruit with registered trademarks Rio Star and Ruby-Sweet, also sometimes promoted as "Reddest" and "Texas Choice".

The Florida Department of Citrus stated "the primary varieties of Florida grapefruit are Ruby Red, Pink, Thompson, Marsh and Duncan. The fresh grapefruit season typically runs from October through June."[1]

Production

The United States of America is the top producer of grapefruit and pomelo followed by China and South Africa.

Grapefruit and pomelo output in 2005

Top Ten Grapefruit (inc. pomelos) Producers — 2007
Country	Production (Tonnes)	Footnote
United States	1580000
People's Republic of China	547000	F
South Africa	430000	F
Mexico	390000	F
Syria	290000	F
Israel	245000	*
Turkey	181923
India	178000	F
Argentina	176000	F
Cuba	175000	F
World	5061023	A
No symbol = official figure, P = official figure, F = FAO estimate, * = Unofficial/Semi-official/mirror data, C = Calculated figure A = Aggregate (may include official, semi-official or estimates); Source: Food And Agricultural Organization of United Nations: Economic And Social Department: The Statistical Division

Growing

Grapefruit are an attractive tree to grow, with the added benefit of fruit. They can be kept outdoors as long as you live in a climate that does not freeze in winter. If you do live in a climate that freezes, they can be grown in a pot, and taken outdoors in warmer months. If you are going to grow a potted tree, in order to get fruit, you will most likely need to buy a dwarf variety.

Grapefruit, like many other fruits can be grown from the seed of a store bought fruit, if you are so inclined, but due to modern hybridisation it may not produce fruit, or the kind of fruit that is produced will not likely be similar to that of the parent fruit.

To grow such a seed, extract the seed from the fruit, and make sure not to let it dry out. A common method is to sit it in a glass of water until any noticeable growth, then plant in a pot. Increase the size of the pot as the plant grows. Grapefruit is the type of tree that will want a considerable amount water, and hot summers to produce good fruit.

Colors and flavors

A grapefruit from southern California

Grapefruit comes in many varieties, determinable by color, which is caused by the pigmentation of the fruit in respect of both its state of ripeness and genetic bent.^[10] The most popular varieties cultivated today are red, white, and pink hues, referring to the inside, pulp color of the fruit. The family of flavors range from highly acidic and somewhat bitter to sweet and tart.^[10] Grapefruit mercaptan, a sulfur-containing terpene, is one of the substances which has a strong influence on the taste and odor of grapefruit, compared with other citrus fruits.^[11]

Drug interactions

Grapefruit mercaptan

Grapefruit can have a number of interactions with drugs, often increasing the effective potency of compounds. Grapefruit contains naringin, bergamottin and dihydroxybergamottin, which inhibit the protein isoform CYP3A4 predominately in the small intestine, but at higher doses, hepatic CYP3A4 inhibition is present as well.^[12] It is via inhibition of this enzyme that grapefruit increases the effects of a variety of drugs by increasing their bioavailability.^{[13][14][15][16][17]} The effect of grapefruit juice with regard to drug absorption was originally discovered in 1989. However, the effect became well-publicized after being responsible for a number of deaths due to overdosing on medication.^[18]

Grapefruit juice may be the first documented, but apple and orange juices have been also implicated in interfering with etoposide, a chemotherapy drug, some beta blocker drugs used to treat high blood pressure, and cyclosporine, taken by transplant patients to prevent rejection of their new organs.^[19]

Unlike other fruits grapefruit contains a large amount of naringin, and it can take up to 72 hours before the effects of the naringin on the CYP3A4 enzyme is seen. This is particularly problematic due to the fact that only 4 oz of grapefruit contain enough naringin to inhibit substrates of CYP3A4.

Nutritional properties

Grapefruit is an excellent source of many nutrients and phytochemicals that contribute to a healthy diet. Grapefruit is a good source of vitamin C,^[10][20] pectin fiber,^[21] and the pink and red hues contain the beneficial antioxidant lycopene.^[10][22] Studies have shown grapefruit helps lower cholesterol^[10][23] and there is evidence that the seeds have high levels of antioxidant properties.^[24] Grapefruit forms a core part of the "grapefruit diet", the theory being that the fruit's low glycemic index is able to help the body's metabolism burn fat.^[25]

Grapefruit seed extract has been claimed to have strong antimicrobial properties, with proven activity against bacteria and fungi. However, no studies have demonstrated any efficacy by grapefruit seed extract as an antimicrobial for either bacteria or fungi. Additionally, although GSE is promoted as a highly effective plant-based preservative by some natural personal care manufacturers, studies have shown that the apparent antimicrobial activity associated with GSE preparations is merely due to contamination with synthetic preservatives.^{[26][27][28][29][30]}

A 2007 study found a correlation between eating a quarter of grapefruit daily and a 30% increase in risk for breast cancer in post-menopausal women. The study points to the inhibition of CYP3A4 enzyme by grapefruit, which metabolizes estrogen.^[31] However, there is a study showing that grapefruit consumption may not increase breast cancer risk. Furthermore, related studies showed a significant decrease in breast cancer risk with greater intake of grapefruit in women who never used hormone therapy.^[32]

Grapefruit sweets

In Costa Rica, especially in Atenas, grapefruits are often cooked to remove their sourness, rendering them as sweets; they are also stuffed with dulce de leche, resulting in a dessert called toronja rellena (stuffed grapefruit).

Other uses

Grapefruit peel oil is used in aromatherapy and it is historically known for its aroma.^[33]

Grapefruit has also been investigated in cancer medicine pharmacodynamics. Although it inhibits the metabolism of some drugs, which is generally considered a bad thing, this allows some cancer drugs to be used at a lower dose, because of inhibited metabolism. This requires a smaller amount, which, in principle, can reduce the overall cost of an "effective" dose.^[34]

It also eases constipation, as it causes loosening of the bowels and stimulates defecation (especially true for pink grapefruit).

A grapefruit is cut in half, and the flesh can be sprinkled with a couple of teaspoons of 'household' sugar (optional), and left covered for an hour or two. The flesh is then eaten as normal.^[35]

See also

• Grapefruit juice
• Grapefruit knife
• Grapefruit seed extract
• Grapefruit spoon
• Pomelo

References

External links

• Grapefruit from "Fruits of warm climates" by Julia F. Morton.
• Grapefruit Utensils-Grapefruit Knife & Grapefruit Spoon
• Grapefruit and Drug Interactions