Pistachio

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Pistachio
Pistachio with ripening fruit
Pistachio with ripening fruit
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Sapindales
Family: Anacardiaceae
Genus: Pistacia
Species: P. vera
Binomial name
Pistacia vera
L.

Pistachio is a common name for a small, deciduous tree, Pistacia vera, of western and central Asia, that produces a commercially popular "Pistachio nut." The term also is used for this edible "nut," which is really an greenish seed with a hard shell, enclosed within part of a fleshy fruit called a drupe. That is, it is a nut in the culinary sense, but not the botanical sense. The term pistachio also is used more broadly for any species of the genus Pistacia, a taxon of flowering plants generally placed in the cashew family Anacardiaceae, although sometimes placed in it own family, Pistaciaceae.

Description

Anacardiaceae is a family of 82 genera and over 700 species of flowering plants (Pell 2004). Some species produce the irritant urushiol. The type genus is Anacardium, the cashew, and it is generally known as the "cashew family." Other species included in this family are mango, poison ivy, sumac, smoke tree, and pistachio. Pistachio is sometimes placed in its own family, the Pistaciaceae.

Members of Anacardiaceae, including pistacio, bear fruits that are classified as drupes. A drupe is a fruit in which an outer fleshy part (exocarp, or skin; and mesocarp, or flesh) surrounds a shell (the pit or stone) of hardened endocarp with a seed inside. These fruits develop from a single carpel. The definitive characteristic of a drupe is that the hard, lignified stone (or pit) is derived from the ovary wall of the flower.

Pistacia is a genus of ten species in the family Anacardiaceae, native to the Canary Islands, northwest Africa, southern Europe, central and eastern Asia and southern North America (Mexico, Texas). They are small trees and shrubs, growing to five to fifteen meters tall. The leaves are alternate, pinnately compound, and can be either evergreen or deciduous depending on species.

The most important commercial species is the pistachio, (Pistacia vera), grown for its edible seeds. The seeds of the other species were also eaten in prehistory, but too small to be worth eating today. The mastic, Pistacia lentiscus, is a shrub or small tree of the Mediterranean region with evergreen leaves. The resin mastic is obtained from it, and is often chewed by people in Turkey. Mastic resin is also used in varnishes and in medicine as a mild stimulant. The terebinth, Pistacia terebinthus, a native of the eastern Mediterranean countries, is tapped for turpentine. The Chinese pistache, Pistacia chinensis, is grown as an ornamental tree, valued for its bright red autumn leaf color; it is also the most frost-tolerant species in the genus.

Pistacia vera, known commonly as "pistachio," grows up to ten meters tall and is native to mountainous regions of Iran, Turkmenistan, and western Afghanistan. It has deciduous pinnate leaves ten to twenty centimeters long. The plants are dioecious, with separate male and female trees. The flowers are apetalous and unisexual, and borne in panicles.

The drupaceous fruit contains an elongated seed with a hard, whitish shell and a striking kernel, which has a mauvish skin and pale green flesh, with a distinctive flavor. This seed is known commercially as a "pistachio" or a "pistachio nut." It is not a "nut" in a botanical sense, as this refers specifically to a simple dry fruit with one seed (rarely two) in which the ovary wall becomes very hard (stony or woody) at maturity; The seed remains unattached or unfused with the ovary wall. The pistachio nut is not a simple, dry fruit but rather is the edible seed of a thin-shelled drupe. It is known as a nut in the less restrictive culinary sense as the term can be applied to any large, oily kernel found within a shell and used in food

When the fruit ripens, the husk changes from green to an autumnal yellow/red and the shells split partially open (see photo). This is known as dehiscence, and happens with an audible pop.



Each pistachio nut weighs around 1 gram, [1] and each pistachio tree averages around 50 kg of nuts, or around 50,000, every two years. [2] Pistachios (as part of the pistacia genus) have existed for about 80 million years. [3]

History

Pistachio is often confused with some of the other nine species in the genus Pistacia, such as P. terebinthus and P. lentiscus. These species have a very different distribution, in the Mediterranean and southwest Asia, and have much smaller nuts, lacking the hard shell of P. vera. Their turpentine-flavoured nuts were a popular food in antiquity. Finds of Pistacia from pre-classical archaeological sites, or references in pre-classical texts, always refer to one of these other species (often P. terebinthus).

Pistachio (in the sense of P. vera) was first cultivated in Western Asia. It reached the Mediterranean world by way of central Iran, where it has long been an important crop. Although known to the Romans, the pistachio nut appears not to have reached the Mediterranean or most of the Near East in any quantity before medieval times. More recently pistachio has been cultivated in California (first commercial harvest in 1976) and Australia. The word pistachio is a Persian loanword, coming into English through Italian, and is a cognate to the Modern Persian word پسته Peste'.

Cultivation and uses

Pistachio nuts in and out of the shell

The kernels are often eaten whole, either fresh or roasted and salted, and are also used in ice cream and confections such as baklava. In July 2003, the Food and Drug Administration (FDA) approved the first qualified health claim specific to nuts lowering the risk of heart disease: "Scientific evidence suggests but does not prove that eating 1.5 ounces (42.5g) per day of most nuts, such as pistachios, as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease".[1]. In research at Pennsylvania State University, pistachios in particular significantly reduced levels of LDL, the 'bad' cholesterol, in the blood of volunteers.[2] Pennsylvania State University's Department of Nutrition and Sciences has also conducted related research on other health benefits of pistachios, including an April 2007 study concluding that pistachios may calm acute stress reaction,[3] and a June 2007 study on the cardiovascular health benefits of eating pistachios.[4]

On the Greek island of Chios, the husk or flesh of the pistachio fruit surrounding the shell is cooked and preserved in syrup.

The shell of the pistachio is naturally a beige colour, but it is sometimes dyed red or green in commercial pistachios. Originally the dye was applied by importers to hide stains on the shells caused when the nuts were picked by hand. However most pistachios are now picked by machine and the shells remain unstained, making dyeing unnecessary (except that some consumers have been led to expect coloured pistachios). Roasted pistachio nuts can be artificially turned red if they are marinated prior to roasting in a salt and strawberry marinade, or salt and citrus salts.

The trees are planted in orchards, and take approximately seven to ten years to reach significant production. Production is alternate bearing or biennial bearing, meaning the harvest is heavier in alternate years. Peak production is reached at approximately 20 years. Trees are usually pruned to size to make the harvest easier. One male tree produces enough pollen for eight to twelve nut-bearing females. Pistachio orchards can be damaged by the fungal disease Botryosphaeria panicle and shoot blight, which kills the flowers and young shoots.

Pistachio trees are fairly hardy in the right conditions, and can survive temperature ranges between −10°C (14°F) in winter to 40°C (104°F) in summer. They need a sunny position and well-drained soil. Pistachio trees do poorly in conditions of high humidity, and are susceptible to root rot in winter if they get too much water and the soil is not sufficiently free draining. Long hot summers are required for proper ripening of the fruit.

Pistachio nuts are highly flammable when stored in large quantities, and are prone to self heating and spontaneous combustion.[5]

Worldwide production

Pistachio output in 2005

Share of a total 2005 worldwide production of 501 thousand metric tonnes[6]:

Country Production
(tonnes)
Iran 190 000
U.S. 140 000
Turkey 60 000
Syria 60 000
China 34 000
Greece 9 500
Italy 2 400
Uzbekistan 1 000
Tunisia 800
Pakistan 200
Madagascar 160
Kyrgyzstan 100
Morocco 50
Cyprus 15
Mexico 7
Mauritius 5

California produces almost all U.S. pistachios, and about half of these are exported, mainly to China, Japan, Europe and Canada. Almost all California pistachios are of the cultivar 'Kerman'. The tree is grafted to a rootstock when the rootstock is one year old. Only a few years after California growers started growing pistachios, the 1979 crisis in Iran would give stronger commercial impetus to the American-based pistachio nut industry. Previous to that time, most Westerners were familiar with only the slightly smaller, deeply red-hued (dyed) nuts produced mainly in Iran, where it is the second largest export after oil. [citation needed]

Notes and references

External links

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  1. FDA Office of Nutritional Products, Labeling and Dietary Supplements, Center for Food Safety and Applied Nutrition (July 2003) “Qualified Health Claims: Letter of Enforcement Discretion - Nuts and Coronary Heart Disease” (Docket No 02P-0505)
  2. Daily Telegraph (London) 2 May 2007
  3. DailyScience.com, via PistachioHealth.com, link and copy of April 2007 Pennsylvania State University research study
  4. PistachioHealth.com link to PDF copy of June 2007 Pennsylvania State University Cardiovascular Health Pistachio study
  5. http://www.containerhandbuch.de/chb_e/scha/index.html?/chb_e/scha/scha_13_06.html Cargo container's handbook].
  6. Food & Agricultural Organization of the UN estimates