Grapefruit

Grapefruit
Grapefruits
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Subclass: Rosidae Order: Sapindales Family: Rutaceae Genus: Citrus Species: C. paradisi
Binomial name
Citrus paradisi Macfad.

Grapefruit is a relatively large, evergreen citrus tree, Citrus paradisi. The term also refers to the round, edible fruit of this plant, which grows in grape-like bunches and has a yellow rind (outer skin) and typically a juicy, acidic pulp.

Grapefruit belongs to the Citrus genus, a taxa of flowering plants in the family Rutaceae (orange family) and a common name for edible fruits of this genus. Other members of the genus include oranges, lemons, limes, citrons, pomelos (pummelo, pommelo), and mandarins (tangerines). Citrus fruits are a distinctive berry with the internal parts divided into segments. The number of natural species is unclear, as many of the named species are hybrids. The grapefruit is believed to have arisen from the pomelo or shaddock (Citrus grandis) or as a hybrid between pomelo and sweet orange (Bender and Bender 2005).

Overview

All citrus trees are of the single genus Citrus and hybridize very easily. That is, there is only one "superspecies," which includes lemons, limes, grapefruit, pomelos, tangerines, and oranges. Citrus is likely the most widely planted fruit for direct human consumption in the world (Katz and Weaver 2003).

Fruits of all members of the genus Citrus are considered berries because they have many seeds, are fleshy and soft, and derive from a single ovary. The distinctive fruit is a hesperidium in that it is a specialized berry with the internal fleshy parts divided into segments (typically 10 to 16) and surrounded by a separable rind (Katz and Weaver 2003). The citrus herperidium is globose to elongated, 4 to 30 centimeters long, and 4 to 20 centimeters in diameter. The rind is leathery and the segments, or "liths," are filled with pulp vesicles.

Citrus plants are small trees or large shrubs, reaching 5 to 15 meters tall, with spiny shoots and alternately arranged evergreen leaves with an entire margin. The flowers are solitary or in small corymbs (a branched cluster of flowers with lower flowers having longer stems). Each flower is 2 to 4 centimeters in diameter, with five (rarely four) white petals and numerous stamens; they are often very strongly scented.

The taxonomy of the genus is complex and the precise number of natural species is unclear, as many of the named species are clonally-propagated hybrids, and there is genetic evidence that even the wild, true-breeding species are of hybrid origin. Cultivated Citrus may be derived from as few as three or four ancestral species. Katz and Weaver (2003) claim that the generally accepted view is that there were three primordial Citrus species—Citrus medica (citrons), Citrus maxima (pumelos), and Citrus reticulata (mandarins)—and that all other types of citrus rose from single or sequential hybridization events between these species or their offspring. The hybridized types of citrus may or may not be recognized as species according to different taxonomies. Thus, anywhere from 3 to 170 species are recognized, with the commonly used system of Swingle recognizing 16 species (Katz and Weaver 2003).

Pink grapefruit

The grapefruit appears either to have arisen from the pomelo (shaddock or Chinese grapefruit, Citrus maxima) as a genetic mutation (sport) or as a hybrid between pomelo and sweet orange (Citrus sinensis in many taxonomies). Although the Citrus genus originated in Asia, Captain Shaddock had brought seeds of the pomelo to the West Indies in the late 17th century.

Grapefruit trees tend to be larger than most citrus trees. They usually are found at around 5 to 6 meters, but can reach 13 to 15 meters. The leaves are dark green, long (up to 150 millimeters), and thin. It produces 5 centimeter (cm) white four-petaled flowers.

The fruit is yellow-skinned in all varieties, some with a pink blush (Herbst 2001). The fruit is largely oblate and ranges in diameter from 10-15 cm and has an acidic segmented pulp, which may range from yellowish-white, to pale yellow-pink, to pink, to brilliant ruby red (Herbst 2001).

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 (GMF 2007). 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 (GMF 2007). Para-1-menthene-8-thiol, a sulfur-containing terpene, is one of the substances that has a strong influence on the taste and odor of grapefruit, compared with other citrus fruits (Buettner and Schieberle 1999).

The fruit has only become popular from the late 19th century; before that it was only grown as an ornamental plant. The United States 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

Grapefruit and pomelo output in 2005

The fruit was first documented in 1750 by Rev. Griffith Hughes describing specimens from Barbados (Quinion 2007). The fruit was originally named the "forbidden fruit" of Barbados (Morton 1987), in comparison to the Tree of Knowledge of Good and Evil in the Garden of Eden (Quinion 2007). Currently, the grapefruit is claimed by some as one of the "Seven Wonders of Barbados" (Bourne 1996).

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. The name grapefruit first appeared in English in a work by botanist John Lunan, Hortus Jamaicanensis (1814) (Bender and Bender 2005; Quinion 2007. While the name apparently arose because the fruit grows in grape-like clusters, and can imaginatively be looked at as grapes when small and green, Lunan had stated that it was "known by the name of grape-fruit, on account of its resemblance in flavour to the grape."

The grapefruit was brought to Florida by Odette Philippe in 1823. Further crosses have produced the tangelo (1905), the minneola (1931), and the sweetie (1984).

Botanically, the grapefruit 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 (Williamson 1997). Grapefruit peel oil is used in aromatherapy and it is historically known for its aromatic scent (Woodward 1991).

Nutritional properties

Pink Grapefruit in slices.

Grapefruit is an excellent source of many nutrients and phytochemicals for a healthy diet. Grapefruit is a good source of vitamin C (GMF 2007; Fellers et al. 1990), pectin fiber (Cerda et al. 1988), and the pink and red hues contain the beneficial antioxidant lycopene (GMF 2007; Lee 2000). Studies have shown grapefruit helps lower cholesterol (GMF 2007; Platt 2000), and there is evidence that the seeds have low levels of antioxidant properties (Armando et al. 1997). 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 (WMUR 2003).

Grapefruit seed extract has been claimed to be a strong antimicrobial with proven activity against bacteria and fungi. However, studies have shown the efficacy of grapefruit seed extract as an antimicrobial is not demonstrated. Although GSE is promoted as a highly effective plant-based preservative by some natural personal care manufacturers, studies indicate the universal antimicrobial activity associated with GSE preparations is merely due to contamination with synthetic preservatives (Sakamoto et al. 1996; von Woedtke et al. 1999; Talepla et al. 2001; Takeoka et al. 2005; Ganzera et al. 2006).

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 (Monroe et al. 2007).

Drug interactions

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 cytochrome P450 isoform CYP3A4 in the intestine. It is via inhibition of this enzyme that grapefruit increases the effects of buspirone (Buspar), carbamazepine, several statin drugs (such as simvastatin), terfenadine, felodipine, nifedipine, verapamil, estradiol, tacrolimus, dextromethorphan (significant only at recreational doses), benzodiazepines, and ciclosporin (He et al. 1998; Bailey et al. 1998; Garg et al. 1998; Bailey and Dresser 2004; Bressler 2006).

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 (Bakalar 2006).

References

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• Armando, C., S. Maythe, and N. P. Beatriz. 1997. Antioxidant activity of grapefruit seed extract on vegetable oils. Journal of the Science of Food and Agriculture 77(4): 463-467. Retrieved October 9, 2007.

• Bailey, D. G., J. Malcolm, O. Arnold, and J. D. Spence. 1998. Grapefruit juice-drug interactions. Br J Clin Pharmacol. 46(2): 101-110. Comment in Br J Clin Pharmacol. 2001 52(2):216-217. Retrieved October 9, 2007.

• Bailey, D. G., and G. K. Dresser. 2004. Interactions between grapefruit juice and cardiovascular drugs. Am J Cardiovasc Drugs 4(5): 281-297.

• Bakalar, N. 2006. Experts reveal the secret powers of grapefruit juice. New York Times March 21, 2006. Retrieved October 9, 2007.

• Bender, D. A., and A. E. Bender. 2005. A Dictionary of Food and Nutrition. New York: Oxford University Press. ISBN 0198609612.

• Bressler, R. 2006. Grapefruit juice and drug interactions. Exploring mechanisms of this interaction and potential toxicity for certain drugs. Geriatrics 61(11): 12-18. Retrieved October 9, 2007.

• Cerda, J. J., F. L. Robbins, C. W. Burgin, T. G. Baumgartner, and R. W. Rice. 1988. The effects of grapefruit pectin on patients at risk for coronary heart disease without altering diet or lifestyle. Clin Cardiol. 11(9): 589-594. Retrieved October 9, 2007.

• He, K., K. R. Iyer, R. N. Hayes, M. W. Sinz, T. F. Woolf, and P. F. Hollenberg. 1998. Inactivation of cytochrome P450 3A4 by bergamottin, a component of grapefruit juice. Chem Res Toxicol. 11(4): 252-259. Retrieved October 9, 2007.

• Garg, S. K., N. Kumar, V. K. Bhargava, and S. K. Prabhakar. 1998. Effect of grapefruit juice on carbamazepine bioavailability in patients with epilepsy. Clin Pharmacol Ther. 64(3): 286-288. Retrieved October 9, 2007.

• Fellers, P. J., S. Nikdel, and H. S. Lee. 1990. Nutrient content and nutrition labeling of several processed Florida citrus juice products. J Am Diet Assoc. 90(8): 1079-1084. Retrieved October 9, 2007.

• Herbst, S. T. 2001. The New Food Lover's Companion: Comprehensive Definitions of Nearly 6,000 Food, Drink, and Culinary Terms. Barron's Cooking Guide. Hauppauge, NY: Barron's Educational Series. ISBN 0764112589.
• Katz, S. H., and W. W. Weaver. 2003. Encyclopedia of Food and Culture. New York: Schribner. ISBN 0684805685.

Lee_HS">Lee HS. Objective measurement of red grapefruit juice color. J Agric Food Chem. 2000 May;48(5):1507-11. Abstract</ref>

George Mateljan Foundation (GMF). 2007. The World's Healthiest Foods; Grapefruit. The George Mateljan Foundation. Article</ref>

Michael Quinion

Margaret P. M Bourne, 1996 (.

Willamson, J. G. 1997. The grapefruit.

WMUR. 2003. .

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External links

• Graedon's Guide to Grapefruit Interactions.
• Grapefruit from "Fruits of warm climates" by Julia F. Morton.
• World's Northernmost Fruiting Grapefruit? in the Chelsea Physic Garden, London.
• Vegetarians in Paradise/Grapefruit History/Grapefruit Nutrition/Grapefruit Folklore/GrapefruitRecipe.

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