The grapefruit is a subtropical citrus tree known for its bitter fruit, an 18th-century hybrid first bred in Jamaica. When found in Barbados it was named the “forbidden fruit”; 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.
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.
Colours and Flavours
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. 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. Grapefruit mercaptan, a sulphur-containing terpene, is one of the substances which has a strong influence on the taste and odor of grapefruit, compared with other citrus fruits.
Grapefruit is an excellent source of many nutrients and phytochemicals that contribute to a healthy diet. Grapefruit is a good source of vitamin C, pectin fiber, and the pink and red hues contain the beneficial antioxidant lycopene. Studies have shown grapefruit helps lower cholesterol and there is evidence that the seeds have high levels of antioxidant properties. 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.
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.
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. 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.
Grapefruit peel oil is used in aromatherapy and it is historically known for its aroma.
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.
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.
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