kiwifruit

Kiwifruit
Kiwifruit
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Ericales
Family:	Actinidiaceae
Genus:	Actinidia
Species:	A. deliciosa
Binomial name
Actinidia deliciosa C.F.Liang.& A.R.Ferguson.

The kiwifruit, often shortened to kiwi in some parts of the world, is the edible berry of a cultivar group of the woody vine Actinidia deliciosa and hybrids between this and other species in the genus Actinidia. The Actinidia is native to South of China.

The most common cultivars of kiwifruit are oval, about the size of a large hen's egg (5–8 cm / 2–3 in long and 4.5–5.5 cm / 1¾–2 in diameter). It has a fibrous, dull brown-green skin and bright green or golden flesh with rows of tiny, black, edible seeds. The fruit has a soft texture and a unique flavour, and today is a commercial crop in several countries, mainly in Italy, China, and New Zealand.

Also known as the Chinese gooseberry,^[1] the fruit was renamed for export marketing reasons in the 1950s; briefly to melonette, and then by New Zealand exporters to kiwifruit. This latter name comes from the kiwi — a flightless bird and New Zealand's national symbol, and also a colloquial name for the New Zealand people.

Names

This fruit had a long history before it was commercialised as kiwifruit and therefore had many other older names.

In Chinese:^[2]

• Macaque peach (獼猴桃 Pinyin: míhóu táo): the most common name
• Macaque pear (獼猴梨 míhóu lí)
• Vine pear (藤梨 téng lí)
• Sunny peach (陽桃 yáng táo), a name originally referring to the Kiwifruit, but often refers to the starfruit
• Wood berry (木子 mù zi)
• Hairy bush fruit (毛木果 máo mù guǒ)
• Unusual fruit or wonder fruit (奇異果 Pinyin: qíyì guǒ, Jyutping: kei4 ji6 gwo2): the most common name in Taiwan and Hong Kong. A quasi-transliteration of "kiwifruit", literally "strange fruit".

Kiwifruit was originally known by its Chinese name, yáng táo (sunny peach) or Mihou Tao (Macaque peach).^[1] After it was introduced to New Zealand by evangelist Isabel Fraser, people in New Zealand thought it had a gooseberry flavour and began to call it the Chinese gooseberry, although it is not related to the Grossulariaceae (gooseberry) family.

New Zealand exported the fruit to the United States in the 1950s. Among the exporters was the prominent produce company Turners and Growers, who were calling the berries melonettes, because the name Chinese gooseberry had political connotations due to the Cold War, and to further distinguish it from real gooseberries, which are prone to a fungus called anthracnose. An American importer, Norman Sondag of San Francisco, complained that melonettes was as bad as Chinese gooseberry because melons and berries were both subject to high import tariffs, and instead asked for a short Maori name that quickly connoted New Zealand.^[1] In June 1959, during a meeting of Turners and Growers management in Auckland, Jack Turner suggested the name kiwifruit which was adopted and later became the industry-wide name.^[3] In the 1960s and 1970s, Frieda Caplan, founder of Los Angeles-based Frieda's Finest (aka Frieda's Inc./Frieda's Specialty Produce) played a key role in popularizing kiwifruit in the United States, convincing supermarket produce managers to carry the odd-looking fruit.^[4]

Most New Zealand kiwifruits are now marketed under the brand-name label Zespri which is trademarked by a marketing company domiciled in New Zealand, ZESPRI International. The branding move also served to distinguish New Zealand kiwifruit from fruit produced by other countries who could cash in on the "Kiwi" name, as it was not trademarked.

History

Kiwifruit output in 2005

Actinidia deliciosa is native to Southern China. Originally known as Yang Tao,^[5] it is declared as the "National Fruit" of the People's Republic of China.^[6] Other species of Actinidia are also found in India and Japan and north into southeastern Siberia. Cultivation spread from China in the early 20th century, when seeds were introduced to New Zealand by Mary Isabel Fraser, the principal of Wanganui Girls' College, who had been visiting mission schools in Yichang, China.^[7] The seeds were planted in 1906 by a Wanganui nurseryman, Alexander Allison, with the vines first fruiting in 1910.

The familiar cultivar Actinidia deliciosa 'Hayward' was developed by Hayward Wright in Avondale, New Zealand around 1924. It was initially grown in domestic gardens, but commercial planting began in the 1940s. Italy is now the leading producer of kiwifruit in the world, followed by New Zealand, Chile, France, Greece, Japan and the United States. In China, kiwifruit was traditionally collected from the wild, but until recently China was not a major producing country.^[8] In China, it is grown mainly in the mountainous area upstream of the Yangtze River. It is also grown in other areas of China, including Sichuan.^[9]

Cultivars

Kiwifruit skin close up

Almost all kiwifruit in commerce belong to a few cultivars of Actinidia deliciosa: 'Hayward', 'Chico', and 'Saanichton 12'. The fruit of these cultivars are practically indistinguishable from each other and match the description of a standard kiwifruit given at the head of this article.

Sliced Golden Kiwifruit

Gold Kiwifruit or "Hinabelle", with yellow flesh and a sweeter, less acidic flavour resembling a tropical fruit salad, is a new Cultivar Group produced by the New Zealand Crown Research Institute, HortResearch and marketed worldwide in increasing volumes. Some wild vines in India have yellow fruit but are small and not commercially viable. Seeds from these plants were imported to New Zealand in 1987 and the company took 11 years to develop the new fruit through cross-pollination and grafting with green kiwifruit vines. Gold Kiwifruit have a smooth, bronze skin, a pointed cap at one end and distinctive golden yellow flesh with a less tart and more tropical flavour than green kiwifruit. It has a higher market price than green kiwifruit. It is less hairy than the green cultivars, so can be eaten whole after rubbing off the thin, fluffy coat. While the skin of kiwifruit is often removed before serving, it is completely edible.

Nutrition

Kiwifruit is a rich source of vitamin C, 1.5 times the DRI scale in the US. Its potassium content by weight is slightly less than that of a banana. It also contains vitamin E^[10], and a small amount of vitamin A^[10][11]. The skin is a good source of flavonoid antioxidants. The kiwifruit seed oil contains on average 62% alpha-linolenic acid, an omega-3 fatty acid.^[12] Usually a medium size kiwifruit contains about 46 calories,^[13] 0.3 g fats, 1 g proteins, 11 g carbohydrates, 75 mg vitamins and 2.6 g dietary fiber.

Kiwifruit is often reported to have mild laxative effects, due to the high level of dietary fiber.^[14]

Raw kiwifruit is also rich in the protein-dissolving enzyme actinidin, (in the same family of thiol proteases as papain), which is commercially useful as a meat tenderizer but can be an allergen for some individuals. Specifically, people allergic to latex, papayas or pineapples are likely to also be allergic to kiwifruit. The fruit also contains calcium oxalate crystals in the form of raphides. Reactions to these chemicals include sweating, tingling and sore mouth; swelling of the lips, tongue and face; rash; vomiting and abdominal pain; and, in the most severe cases, breathing difficulties, wheezing and collapse. The most common symptoms are unpleasant itching and soreness of the mouth, with the most common severe symptom being wheezing. Severe symptoms are most likely to occur in young children.

This enzyme makes raw kiwifruit unsuitable for use in desserts containing milk or any other dairy products which are not going to be served within hours, because it soon begins to digest milk proteins. This applies to gelatin-based desserts as well, as the actinidin will dissolve the collagen proteins in gelatin very quickly, either liquifying the dessert, or preventing it from solidifying. However, the U.S. Department of Agriculture suggests that cooking the fruit for a few minutes before adding it to the gelatin will overcome this effect.^[15] Sliced kiwifruit has long been regularly used as a garnish atop whipped cream on New Zealand's national dessert, the pavlova. It can also be used in curry [2]

Kiwifruit also serves as a natural blood thinner. A recent study performed at the University of Oslo in Norway reveals that—similar to popular mainstream aspirin therapy—consuming two to three kiwifruit daily for 28 days significantly thins the blood, reducing the risk of clots, and lowers fat in the blood that can cause blockages.^[16]

The kiwifruit skin is edible and contains high amounts of dietary fiber. In a fully matured kiwifruit one study showed that this as much as tripled the fiber content of the fruit. In addition, as many of the vitamins are stored immediately under the skin, leaving the skin intact greatly increases the vitamin c consumed by eating a single piece of kiwifruit when compared to eating it peeled. As with all fruit, it is recommended that if eating the skin, the fruit be washed prior to consumption.

Kiwifruit is one of the best natural sources of lutein and zeaxanthin.^[17]

Cultivation

Top kiwifruit producers - 2005
(million metric ton)

Italy	0.48
New Zealand	0.28
Chile	0.15
France	0.08
Greece	0.04
Japan	0.04
Iran	0.02
United States	0.02
Canada	0.01
Cambodia	0.01
World Total	1.14
Source: UN Food and Agriculture Organization (FAO)[3]

Young kiwifruit orchard, North Island, New Zealand

Kiwifruit can be grown in most temperate climates with adequate summer heat. Where Actinidia deliciosa is not hardy, other species can be grown as substitutes.

Kiwifruit is commercially grown on sturdy support structures, as it can produce several tonnes per hectare, more than the rather weak vines can support. These are generally equipped with a watering system for irrigation and frost protection in the spring.

Kiwifruit vines require vigorous pruning, similar to that of grapevines. Fruit is borne on one-year-old and older canes, but production declines as each cane ages. Canes should be pruned off and replaced after their third year.

Kiwifruit plants are normally dioecious, meaning that individual plants are male or female. Only female plants bear fruit, and only when pollenized by a male plant. One male pollenizer is required for each three to eight female vines. An exception is the cultivar 'Issai', a hybrid (Actinidia arguta x polygama) from Japan, which produces perfect flowers and can self-pollinate; unfortunately it lacks vigour, is less hardy than most A. arguta forms and is not a large producer.

Kiwifruit is notoriously difficult to pollinate because the flowers are not very attractive to bees. Some producers blow collected pollen over the female flowers. But generally the most successful approach is saturation pollination, where the bee populations are made so large (by placing hives in the orchards) that bees are forced to use this flower because of intense competition for all flowers within flight distance.

Gallery

Kiwifruit orchard in Himachal Pradesh, India	Female flower	Male flowers	Sliced kiwifruit
Kiwifruit.

See also

• Nutrition
• Phytonutrients

Notes

External links

Wikimedia Commons has media related to: Kiwifruit

Wikispecies has information related to: Actinidia deliciosa

• How to grow kiwifruit vines and nutritional data
• Purdue University NewCROP
• Kiwifruits in Australia
• Zespri International Limited company
• Mary Isabel Frasier
• Photos of kiwifruit and alfalfa pollination in California