Monday, November 29, 2010

Healthy Fruit: Peach

The peach tree (Prunus persica) is a species of Prunus native to China that bears an edible juicy fruit called a peach. It is a deciduous tree growing to 4–10 m (13–33 ft) tall, belonging to the subfamily Prunoideae of the family Rosaceae. It is classified with the almond in the subgenus Amygdalus within the genus Prunus, distinguished from the other subgenera by the corrugated seed shell.
The leaves are lanceolate, 7–16 cm (2.8–6.3 in) long, 2–3 cm (0.79–1.2 in) broad, pinnately veined. The flowers are produced in early spring before the leaves; they are solitary or paired, 2.5–3 cm diameter, pink, with five petals. The fruit has yellow or whitish flesh, a delicate aroma, and a skin that is either velvety (peaches) or smooth (nectarines) in different cultivars. The flesh is very delicate and easily bruised in some cultivars, but is fairly firm in some commercial varieties, especially when green. The single, large seed is red-brown, oval shaped, approximately 1.3–2 cm long, and is surrounded by a wood-like husk. Peaches, along with cherries, plums and apricots, are stone fruits (drupes).
The scientific name persica, along with the word "peach" itself and its cognates in many European languages, derives from an early European belief that peaches were native to Persia (now Iran). The modern botanical consensus is that they originate in China, and were introduced to Persia and the Mediterranean region along the Silk Road before Christian times. Cultivated peaches are divided into clingstones and freestones, depending on whether the flesh sticks to the stone or not; both can have either white or yellow flesh. Peaches with white flesh typically are very sweet with little acidity, while yellow-fleshed peaches typically have an acidic tang coupled with sweetness, though this also varies greatly. Both colours often have some red on their skin. Low-acid white-fleshed peaches are the most popular kinds in China, Japan, and neighbouring Asian countries, while Europeans and North Americans have historically favoured the acidic, yellow-fleshed kinds.
Although its botanical name Prunus persica suggests the peach is native to Persia, peaches actually originated in China where they have been cultivated since the early days of Chinese culture. Peaches were mentioned in Chinese writings as far back as the 10th century BC and were a favoured fruit of kings and emperors. Recently, the history of cultivation of peaches in China has been extensively reviewed citing numerous original manuscripts dating back to 1100 B.C.
Its English name derives originally from the Latin Prunus persica, then persica, then pessica, then pesca, then the French peche, then peach in Middle English.
The peach was brought to India and Western Asia in ancient times. Alexander the Great introduced the fruit into Europe after he conquered the Persians. Then it was brought to America by Spanish explorers in the 16th century and eventually made it to England and France in the 17th century, where it was a prized, albeit rare, treat.
California today grows 65% of peaches grown for commercial production in the United States, but the states of Colorado, Michigan, and Washington also grow a significant amount. Italy, China, India and Greece are major producers of peaches outside of the United States.
Peach plants grow very well in a fairly limited range, since they have a chilling requirement that tropical areas cannot satisfy, and they are not very cold-hardy. The trees themselves can usually tolerate temperatures to around -26 to -30 °C (-15 to -22 °F), although the following season's flower buds are usually killed at these temperatures, leading to no crop that summer. Flower bud kill begins to occur between -15 and -25 °C (5 and -13 °F) depending on the cultivar (some are more cold-tolerant than others) and the timing of the cold, with the buds becoming less cold tolerant in late winter. Certain cultivars are more tender and others can tolerate a few degrees colder. In addition, a lot of summer heat is required to mature the crop, with mean temperatures of the hottest month between 20 and 30 °C (68 and 86 °F). Another problematic issue in many peach-growing areas is spring frost. The trees tend to flower fairly early in spring. The blooms often can be damaged or killed by freezes; typically, if temperatures drop below about −4 °C (24.8 °F), most flowers will be killed. However, if the flowers are not fully open, they can tolerate a couple of degrees colder.
Most peach trees sold by nurseries are named cultivars budded or grafted onto a suitable rootstock. It is also possible to grow a tree from either a peach or nectarine seed, but the fruit quality of the resulting tree will be very unpredictable. Peaches should be located in full sun, and with good air flow. This allows cold air to flow away on frosty nights and keeps the area cool in summer. Peaches are best planted in early winter, as this allows time for the roots to establish and to sustain the new spring growth. When planting in rows, plant north–south.
For optimum growth, peach trees require a constant supply of water. This should be increased shortly before the harvest. The best tasting fruit is produced when the peach is watered throughout the season. Drip irrigation is ideal, with at least one dripper per tree. Although it is better to use multiple drippers around the tree, this is not necessary. A quarter of the root being watered is sufficient.
Peaches should be stored at room temperature and refrigeration should be avoided as this can lessen the taste of the peach. Peaches do not ripen after being picked from the tree, so storing for ripening is not necessary.
Peaches are known in China, Japan, Korea, Laos, and Vietnam not only as a popular fruit but for the many folk tales and traditions associated with it.
Nutrition and health
A medium peach 75 g (2.6 oz), has 30 Calories, 7 g of carbohydrates (6 g sugars and 1 g fibre), 1 g of protein, 140 mg of potassium, and 8% of the daily value (DV) for vitamin C.
As with many other members of the rose family, peach seeds contain cyanogenic glycosides, including amygdalin (note the subgenus designation: Amygdalus). These substances are capable of decomposing into a sugar molecule and hydrogen cyanide gas. While peach seeds are not the most toxic within the rose family, that dubious honour going to the bitter almond, large doses of these chemicals from any source are hazardous to human health.
Peach allergy or intolerance is a relatively common form of hypersensitivity to proteins contained in peaches and related fruit (almonds). Symptoms range from local symptoms (e.g. oral allergy syndrome, contact urticaria) to systemic symptoms including anaphylaxis (e.g. urticaria, angioedema, gastrointestinal and respiratory symptoms). Adverse reactions are related to the "freshness" of the fruit: peeled or canned fruit may be tolerated.

Peaches (edible part) : Nutritional value per 100 g (3.5 oz)
Energy 165 kJ (39 kcal)

Carbohydrates 9.5 g
Sugars 8.4 g | Dietary fiber 1.5 g
Fat 0.3 g | Protein 0.9 g
Vitamin A equiv. 16 μg (2%)
Folate (Vit. B9) 4 μg (1%) | Vitamin C 6.6 mg (11%)
Iron 0.25 mg (2%) | Potassium 190 mg (4%)
Percentages are relative to US recommendations for adults. 
Source: USDA Nutrient database

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Sunday, November 28, 2010

Healthy Fruit: Pear

The pear is a fruit tree of genus Pyrus and also the name of the tree's edible pomaceous fruit. The pear is classified in subtribe Pyrinae within tribe Pyreae and is a perennial. The apple (Malus × domestica), which it resembles in floral structure, is also a member of this subcategory.
The English word “pear” is probably from Common West Germanic *pera, probably a loanword of Vulgar Latin pira, the plural of pirum, akin to Greek apios which is likely of Semitic origin. The place name Perry can indicate the historical presence of pear trees. The term "pyriform" is sometimes used to describe something which is "pear-shaped".
Pears grow in the sublime orchard of Alcinous, in Odyssey vii: "Therein grow trees, tall and luxuriant, pears and pomegranates and apple-trees with their bright fruit, and sweet figs, and luxuriant olives. Of these the fruit perishes not nor fails in winter or in summer, but lasts throughout the year."
Pears have been cultivated in China for approximately 3000 years. The genus is thought to have originated in present-day western China in the foothills of the Tian Shan, a mountain range of Central Asia, and to have spread to the north and south along mountain chains, evolving into a diverse group of over 20 widely recognized primary species. The enormous number of varieties of the cultivated European pear (Pyrus communis subsp. communis), are without doubt derived from one or two wild subspecies (P. communis subsp. pyraster and P. communis subsp. caucasica), widely distributed throughout Europe, and sometimes forming part of the natural vegetation of the forests.
Asian species with medium to large edible fruit include P. pyrifolia, P. ussuriensis, P. × bretschneideri, P. × sinkiangensis, and P. pashia. Other small-fruited species are frequently used as rootstocks for the cultivated forms.
Pears are native to coastal and mildly temperate regions of the Old World, from western Europe and north Africa east right across Asia. They are medium sized trees, reaching 10–17 m tall, often with a tall, narrow crown; a few species are shrubby. The leaves are alternately arranged, simple, 2–12 cm long, glossy green on some species, densely silvery-hairy in some others; leaf shape varies from broad oval to narrow lanceolate. Most pears are deciduous, but one or two species in southeast Asia are evergreen. Most are cold-hardy, withstanding temperatures between −25 °C and −40 °C in winter, except for the evergreen species, which only tolerate temperatures down to about −15 °C. The flowers are white, rarely tinted yellow or pink, 2–4 cm diameter, and have five petals. Like that of the related apple, the pear fruit is a pome, in most wild species 1–4 cm diameter, but in some cultivated forms up to 18 cm long and 8 cm broad; the shape varies in most species from oblate or globose, to the classic pyriform 'pear-shape' of the European Pear with an elongated basal portion and a bulbous end.
The fruit is composed of the receptacle or upper end of the flower-stalk (the so-called calyx tube) greatly dilated. Enclosed within its cellular flesh is the true fruit: five cartilaginous carpels, known colloquially as the "core". From the upper rim of the receptacle are given off the five sepals, the five petals, and the very numerous stamens. The pear is very similar to the apple in cultivation, propagation and pollination. The pear and the apple are also related to the quince.
Pears and apples cannot always be distinguished by the form of the fruit; some pears look very much like some apples. One major difference is that the flesh of pear fruit contains stone cells (also called "grit"). Pear trees and apple trees do have several visible differences. Another interesting difference is that apples, when placed carefully in water, will float; pears will sink. There are about 30 primary species, major subspecies, and naturally occurring interspecific hybrids of pears.
Pears may be stored at room temperature until ripe. Pears are ripe when flesh around stem gives to gentle pressure. Ripe pears are optimally stored refrigerated, uncovered in a single layer, where they have a shelf life of 2 to 3 days.
Pears are consumed fresh, canned, as juice, and dried. The juice can also be used in jellies and jams, usually in combination with other fruits or berries. Fermented pear juice is called perry or pear cider.
Pears ripen at room temperature. They will ripen faster if placed next to bananas in a fruit bowl. Refrigerate pears to slow further ripening. Pear Bureau Northwest offers tips on ripening and judging ripeness: While the skin on Bartlett pears changes from green to yellow as they ripen, most varieties show little color change as they ripen. Because pears ripen from the inside out, the best way to judge ripeness is to "Check the Neck." To Check the Neck for ripeness, apply gentle thumb pressure to the neck, or stem end of the pear. If it yields to gentle pressure, then the pear is ripe, sweet, and juicy. If it is firm, leave pear at room temperature and Check the Neck daily for ripeness. Source: Pear Bureau Northwest
Health Benefits
Pears are an excellent source of dietary fiber and a good source of Vitamin C. The nutritional content of a medium-sized fresh pear weighing 166 g (5.9 oz) is as follows: 100 calories, 26 g of carbohydrates (16 g sugars and  6 g fibre), 1 g of protein, 190 mg (5%) of potassium, 2% and 10% of the daily value (DV) for calcium and vitamin C.

Pear, raw : Nutritional value per 100 g (3.5 oz)
Energy 242 kJ (58 kcal) | Carbohydrates 15.46 g
Sugars 9.80 g | Dietary fiber 3.1 g | Protein 0.38 g
Thiamine (Vit. B1) 0.012 mg (1%)
Riboflavin (Vit. B2) 0.025 mg (2%)
Niacin (Vit. B3) 0.157 mg (1%)
Pantothenic acid (B5) 0.048 mg (1%) | Vitamin B6 0.028 mg (2%)
Folate (Vit. B9) 7 μg (2%) | Vitamin C 4.2 mg (7%)
Calcium 9 mg (1%) | Iron 0.17 mg (1%)
Magnesium 7 mg (2%) | Phosphorus 11 mg (2%)
Potassium 119 mg (3%) | Zinc 0.10 mg (1%)
Percentages are relative to US recommendations for adults.
Source: USDA Nutrient database
Pears are less allergenic than many other fruits, and pear juice is therefore sometimes used as the first juice introduced to infants. However, caution is recommended for all fruit juice consumption by infants as studies have suggested a link between excessive fruit juice consumption and reduced nutrient intake as well as a tendency towards obesity. Pears are low in salicylates and benzoates and are therefore recommended in exclusion diets for allergy sufferers. Along with lamb and rice, pears may form part of the strictest exclusion diet for allergy sufferers although allergies to these foods are possible.
Pears can be useful in treating inflammation of mucous membranes, colitis, chronic gallbladder disorders, arthritis, and gout. Pears can also be beneficial in lowering high blood pressure, controlling blood cholesterol levels, and increasing urine acidity. In ancient Greece, pears were used to treat nausea. Most of the fiber is insoluble, making pears a good laxative. The gritty fiber content may cut down on the number of cancerous colon polyps. Most of the vitamin C, as well as the dietary fiber, is contained within the skin of the fruit.

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Monday, November 22, 2010

Healthy Fruit: Papaya

The papaya (from Carib via Spanish), papaw or pawpaw is the fruit of the plant Carica papaya, in the genus Carica. It is native to the tropics of the Americas, and was first cultivated in Mexico several centuries before the emergence of the Mesoamerican classic cultures.
It is a large tree-like plant, with a single stem growing from 5 to 10 metres (16 to 33 ft) tall, with spirally arranged leaves confined to the top of the trunk. The lower trunk is conspicuously scarred where leaves and fruit were borne. The leaves are large, 50–70 centimetres (20–28 in) diameter, deeply palmately lobed with 7 lobes. The tree is usually unbranched if unlopped. The flowers are similar in shape to the flowers of the Plumeria but are much smaller and wax-like. They appear on the axils of the leaves, maturing into the large 15–45 centimetres (5.9–18 in) long, 10–30 centimetres (3.9–12 in) diameter fruit. The fruit is ripe when it feels soft (like a ripe avocado or a bit softer) and its skin has attained an amber to orange hue. It is the first fruit tree to have its genome deciphered.
In North America the term pawpaw may also refer to the fruit of trees in the unrelated North American genus Asimina. However, pawpaw and papaw are common synonyms of papaya both in North America and elsewhere. It is sometimes called mugua and is therefore confused with Chaenomeles speciosa or Pseudocydonia sinensis which are called mugua in Traditional Chinese Medicine.
Originally from southern Mexico, particularly Chiapas and Veracruz, Central America and northern South America, the papaya is now cultivated in most tropical countries, such as Brazil, Bangladesh, Pakistan, India, Indonesia, South Africa, Sri Lanka, Vietnam, Philippines and Jamaica. In cultivation, it grows rapidly, fruiting within 3 years. It is, however, highly frost sensitive. The papaya fruit is susceptible to the Fruit Fly. This wasp-like fly lays its eggs in young fruit.
In the 1990s, the papaya ringspot virus threatened to wipe out Hawaii’s papaya industry completely. Two varieties of papaya, SunUp and Rainbow, that had been genetically modified to be resistant to the virus, were introduced into Hawaii. By 2010 80% of Hawaiian papaya was genetically modified. Today there is still no conventional or organic method of controlling the ringspot virus. In 2004, non-genetically modified and organic papayas throughout Hawaii had experienced hybridization with the genetically modified varieties.
Papaya can be used as a food, a cooking aid, and in medicine. The stem and bark are also used in rope production. The ripe fruit is usually eaten raw, without skin or seeds. The unripe green fruit of papaya can be eaten cooked, usually in curries, salads and stews. It has a relatively high amount of pectin, which can be used to make jellies. Green papaya is used in Thai cuisine, both raw and cooked.
The black seeds are edible and have a sharp, spicy taste. They are sometimes ground up and used as a substitute for black pepper. In some parts of Asia the young leaves of papaya are steamed and eaten like spinach. In parts of the world papaya leaves are made into tea as a preventative for malaria, though there is no real scientific evidence for the effectiveness of this treatment.
Green papaya fruit and the tree's latex are both rich in an enzyme called papain, a protease which is useful in tenderizing meat and other proteins. Its ability to break down tough meat fibers was used for thousands of years by indigenous Americans. It is included as a component in powdered meat tenderizers.
Papaya is frequently used as a hair conditioner, but should be used in small amounts. Papaya releases a latex fluid when not quite ripe, which can cause irritation and provoke allergic reaction in some people. The papaya fruit, seeds, latex, and leaves also contains carpaine, an anthelmintic alkaloid (a drug that removes parasitic worms from the body), which can be dangerous in high doses.
It is speculated that unripe papayas may cause miscarriage due to latex content that may cause uterine contractions which may lead to a miscarriage. Papaya seed extracts in large doses have a contraceptive effect on rats and monkeys, but in small doses have no effect on the unborn animals.
Excessive consumption of papaya can cause carotenemia, the yellowing of soles and palms, which is otherwise harmless. However, a very large dose would need to be consumed; papaya contains about 6% of the level of beta carotene found in carrots (the most common cause of carotenemia) per 100g.
The juice has an antiproliferative effect on in vitro liver cancer cells, probably due to its component of lycopene or immune system stimulation. Papaya seed could be used as an antibacterial agent for Escherichia coli, Staphylococcus aureus or Salmonella typhi, although further research is needed before advocating large-scale therapy. Papaya seed extract may be nephroprotective (protect the kidneys) in toxicity-induced kidney failure.
Papaya, raw : Nutritional value per 100 g (3.5 oz)
Energy 163 kJ (39 kcal) | Carbohydrates 9.81 g
Sugars 5.90 g | Dietary fiber 1.8 g
Fat 0.14 g | Protein 0.61 g
Vitamin A equiv. 55 μg (6%) | - beta-carotene 276 μg (3%)
Thiamine (Vit. B1) 0.04 mg (3%)
Riboflavin (Vit. B2) 0.05 mg (3%)
Niacin (Vit. B3) 0.338 mg (2%)
Vitamin B6 0.1 mg (8%) | Vitamin C 61.8 mg (103%)
Calcium 24 mg (2%) | Iron 0.10 mg (1%)
Magnesium 10 mg (3%) | Phosphorus 5 mg (1%)
Potassium 257 mg (5%) | Sodium 3 mg (0%)

Percentages are relative to US
recommendations for adults.
Source: USDA Nutrient database

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Wednesday, November 17, 2010

Healthy Fruit: Orange

An orange—specifically, the sweet orange—is the citrus Citrus × sinensis (syn. Citrus aurantium L. var. dulcis L., or Citrus aurantium Risso) and its fruit. The orange is a hybrid of ancient cultivated origin, possibly between pomelo (Citrus maxima) and mandarin (Citrus reticulata). It is a small flowering tree growing to about 10 m tall with evergreen leaves, which are arranged alternately, of ovate shape with crenulate margins and 4–10 cm long. The orange fruit is a hesperidium, a type of berry.
Oranges originated in Southeast Asia. The fruit of Citrus sinensis is called sweet orange to distinguish it from Citrus aurantium, the bitter orange. The name is thought to ultimately derive from the Sanskrit for the orange tree, with its final form developing after passing through numerous intermediate languages. In a number of languages, it is known as a "Chinese apple" (e.g. Dutch Sinaasappel, "China's apple").
All citrus trees are of the single genus, Citrus, and remain largely interbreedable; that is, there is only one "superspecies" which includes grapefruits, lemons, limes, and oranges. Nevertheless, names have been given to the various members of the genus, oranges often being referred to as Citrus sinensis and Citrus aurantium. Fruits of all members of the genus Citrus are considered berries because they have many seeds, are fleshy, soft, and derive from a single ovary. An orange seed is called a pip. The white thread-like material attached to the inside of the peel is called pith.
Blood orange
Blood oranges are a natural variety of C. sinensis derived from abnormal pigmentation of the fruit, that gives its pulp a streaking red colour. The juice produced from such oranges is often dark burgundy, hence reminiscent of blood. Original blood oranges were first discovered and cultivated in the 15th century in Sicily, however since then their cultivation became worldwide, and most blood oranges today are hybrids.
The fruit has found a niche as an interesting ingredient variation on traditional Seville marmalade, with its striking red streaks and distinct flavour. The scarlet navel is a variety with the same dual-fruit mutation as the navel orange.
Navel orange
According to Dorsett, Shamel, and Popenoe (1917) of the U.S. Department of Agriculture who conducted a study at first hand, a single mutation in 1810 to 1820 in a Selecta orange tree planted at a monastery near Bahia in Brazil, probably yielded the navel orange, also known as the Washington, Riverside, or Bahia navel. However, a researcher at the University of California, Riverside, believes that the parent variety was more likely the Portuguese navel (Umbigo) orange described by Risso and Poiteau (1818-22). The mutation causes the orange to develop a second orange at the base of the original fruit, opposite the stem, as a conjoined twin in a set of smaller segments embedded within the peel of the larger orange. From the outside, it looks similar to the human navel, hence its name.
Because the mutation left the fruit seedless, and therefore sterile, the only means available to cultivate more of this new variety is to graft cuttings onto other varieties of citrus tree. It was introduced into Australia in 1824 and Florida in 1835. Twelve such cuttings of the original tree were transplanted to Riverside, California in 1870, which eventually led to worldwide popularity. The California Citrus State Historic Park preserves this history in Riverside, California, as does the Orcutt Ranch Horticulture Center in Los Angeles County, California.
Today, navel oranges continue to be produced via cutting and grafting. This does not allow for the usual selective breeding methodologies, and so not only do the navel oranges of today have exactly the same genetic makeup as the original tree, and are therefore clones, all navel oranges can be considered to be the fruit of that single nearly two hundred year-old tree. This is similar to the common yellow seedless banana, the Cavendish. On rare occasions, however, further mutations can lead to new varieties
Persian orange
The Persian orange, grown widely in southern Europe after its introduction to Italy in the 11th century, was bitter. Sweet oranges brought to Europe in the 15th century from India by Portuguese traders quickly displaced the bitter, and are now the most common variety of orange cultivated. The sweet orange will grow to different sizes and colours according to local conditions, most commonly with ten carpels, or segments, inside.
Some South East Indo-European tongues name the orange after Portugal, which was formerly the main source of imports of sweet oranges. Examples are Bulgarian portokal, Greek portokali, Persian porteqal, Albanian "portokall", Macedonian portokal, and Romanian portocala. Also in South Italian dialects (Neapolitan), orange is named portogallo or purtualle, literally "the Portuguese one". Related names can also be found in other languages: Turkish Portakal, Arabic al-burtuqal, Amharic birtukan, and Georgian phortokhali.
Portuguese, Spanish, Arab, and Dutch sailors planted citrus trees along trade routes to prevent scurvy. On his second voyage in 1493, Christopher Columbus brought the seeds of oranges, lemons and citrons to Haiti and the Caribbean. They were introduced in Florida (along with lemons) in 1513 by Spanish explorer Juan Ponce de Leon, and were introduced to Hawaii in 1792.
Valencia orange
The Valencia or Murcia orange is one of the sweet oranges used for juice extraction. It is a late-season fruit, and therefore a popular variety when the navel oranges are out of season. For this reason, the orange was chosen to be the official mascot of the 1982 FIFA World Cup, which was held in Spain. The mascot was called "Naranjito" ("little orange"), and wore the colours of the Spanish football team uniform.
Like all citrus fruits, the orange is acidic, with a pH level of around 2.5-3; depending on the age, size and variety of the fruit. Although this is not, on average, as strong as the lemon, it is still quite acidic on the pH scale – as acidic as household vinegar.
Orange, raw, Florida : Nutritional value per 100 g (3.5 oz)
Energy 192 kJ (46 kcal) | Carbohydrates 11.54 g
Sugars 9.14 g | Dietary fiber 2.4 g
Fat 0.21 g | Protein 0.70 g
Thiamine (Vit. B1) 0.100 mg (8%)
Riboflavin (Vit. B2) 0.040 mg (3%)
Niacin (Vit. B3) 0.400 mg (3%)
Pantothenic acid (B5) 0.250 mg (5%)
Vitamin B6 0.051 mg (4%) | Folate (Vit. B9) 17 μg (4%)
Vitamin C 45 mg (75%)
Calcium 43 mg (4%) | Iron 0.09 mg (1%)
Magnesium 10 mg (3%) | Phosphorus 12 mg (2%)
Potassium 169 mg (4%) | Zinc 0.08 mg (1%)
Percentages are relative to US recommendations for adults.
Source: USDA Nutrient database

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