|Pistacia vera (Kerman cultivar) fruits ripening|
|Roasted pistachio seed with shell|
The pistachio (//, -//, Persian: پسته ), Pistacia vera, a member of the cashew family, is a small tree originally from Central Asia and the Middle East. Pistachio trees can be found in regions of Iran, Syria, Lebanon, Turkey, Greece, Xinjiang (China), Tunisia, Kyrgyzstan, Tajikistan, Turkmenistan, India, Egypt, Italy (Sicily), Uzbekistan, Afghanistan (especially in the provinces of Samangan and Badghis), and the United States, specifically in California. The tree produces seeds that are widely consumed as food.
However, it is native only to the eastern Mediterranean (Cyprus and Turkey to Israel and Syria), Central Asia (Turkmenistan, Uzbekistan, Afghanistan, Tajikistan, and Kyrgyzstan) and Xinjiang.
Pistacia vera often is confused with other species in the genus Pistacia that are also known as pistachio. These species can be distinguished from P. vera by their geographic distributions (in the wild), and their seeds which are much smaller and have a shell that is soft.
Archaeologists have found evidence from excavations at Jarmo in northeastern Iraq that pistachio seeds were a common food as early as 6750 BC. The Hanging Gardens of Babylon were said to have contained pistachio trees during the reign of King Merodach-Baladan about 700 BC. The modern pistachio P. vera was first cultivated in Western Asia, where it has long been an important crop in cooler parts of Iran and Iraq. It appears in Dioscurides as pistakia πιστάκια, recognizable as P. vera by its comparison to pine nuts. Its cultivation spread into the Mediterranean world by way of Persia from Syria.
Additionally, remains of the Atlantic pistachio and pistachio seed along with nut-cracking tools were discovered by archaeologists at the Gesher Benot Ya'aqov site in Israel's Hula Valley, dated to 78,000 years ago.
Pliny the Elder in his Natural History asserts that pistacia, “well known among us,” was one of the trees unique to Syria, and that the seed was introduced into Italy by the Roman Proconsul in Syria, Lucius Vitellius the Elder (in office in 35 AD) and into Hispania at the same time by Flaccus Pompeius. The early sixth-century manuscript De observatione ciborum (“On the observance of foods”) by Anthimus implies that pistacia remained well known in Europe in Late Antiquity. The pistachio is one of three seeds mentioned in the Bible. The pistachio is mentioned once, in Genesis 43:11, as is the walnut in Song of Songs 6:11, while the almond is mentioned many times.
More recently, the pistachio has been cultivated commercially in many parts of the English-speaking world, in Australia, and in New Mexico and California, of the United States, where it was introduced in 1854 as a garden tree. David Fairchild of the United States Department of Agriculture introduced hardier cultivars collected in China to California in 1904 and 1905, but it was not promoted as a commercial crop until 1929. Walter T. Swingle’s pistachios from Syria had already fruited well at Niles by 1917.
The earliest records of pistachio in English are around roughly year 1400, with the spellings “pistace” and “pistacia”. The word pistachio comes from medieval Italian pistacchio, which is from classical Latin pistacium, which is from ancient Greek pistákion and pistákē, which is generally believed to be from Middle Persian, although unattested in Middle Persian. Later in Persian, the word is attested in Persian as pista. As mentioned, the tree came to the ancient Greeks from Western Asia.
Pistachio is a desert plant, and is highly tolerant of saline soil. It has been reported to grow well when irrigated with water having 3,000–4,000 ppm of soluble salts. Pistachio trees are fairly hardy in the right conditions, and can survive temperatures ranging between −10 °C (14 °F) in winter and 48 °C (118 °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.
The bush grows up to 10 m (33 ft) tall. It has deciduous pinnate leaves 10–20 centimeters (4–8 inches) long. The plants are dioecious, with separate male and female trees. The flowers are apetalous and unisexual, and borne in panicles.
The fruit is a drupe, containing an elongated seed, which is the edible portion. The seed, commonly thought of as a nut, is a culinary nut, not a botanical nut. The fruit has a hard, creamish exterior shell. The seed has a mauvish skin and light green flesh, with a distinctive flavor. When the fruit ripens, the shell changes from green to an autumnal yellow/red, and abruptly splits part way open (see photo). This is known as dehiscence, and happens with an audible pop. The splitting open is a trait that has been selected by humans. Commercial cultivars vary in how consistently they split open.
Each pistachio tree averages around 50 kilograms (110 lb) of seeds, or around 50,000, every two years.
The shell of the pistachio is naturally a beige color, but it is sometimes dyed red or green in commercial pistachios. Originally, dye was applied by importers to hide stains on the shells caused when the seeds were picked by hand. Most pistachios are now picked by machine and the shells remain unstained, making dyeing unnecessary except to meet ingrained consumer expectations. Roasted pistachio seeds can be artificially turned red if they are marinated prior to roasting in a salt and strawberry marinade, or salt and citrus salts.
|Top Ten Pistachio Producers
Iran, the United States and Turkey are the major producers of pistachios. 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 drupe-bearing females. Harvesting in the United States and in Greece is often accomplished by using shaking equipment to shake the drupes off the tree. After hulling and drying, pistachios are sorted according to open mouth and closed mouth shell. Sun drying has been found to be the best method of drying. Then they are roasted or processed by special machines to produce pistachio kernels.
Pistachio trees are vulnerable to a wide variety of diseases (see list of pistachio diseases). Among these is infection by the fungus Botryosphaeria, which causes panicle and shoot blight (i.e., kills flowers and young shoots), and can damage entire pistachio orchards.
In Greece, the cultivated type of pistachios is different. It has an almost-white shell, a sweet taste, a red-green kernel and a little bit more close mouth shell than "Kerman" variety. Most of the production in Greece comes from the island of Aegina and the region of Thessaly - Almyros.
The kernels are often eaten whole, either fresh or roasted and salted, and are also used in pistachio ice cream, kulfi, spumoni, historically in Neapolitan ice cream, pistachio butter, pistachio paste and confections such as baklava, pistachio chocolate, pistachio halva, pistachio lokum or biscotti and cold cuts such as mortadella. Americans make pistachio salad, which includes fresh pistachios or pistachio pudding, whipped cream, and canned fruit.
In July 2003, the Food and Drug Administration (FDA) approved the first qualified health claim specific to seeds lowering the risk of heart disease: "Scientific evidence suggests but does not prove that eating 1.5 ounces (42.5 g) 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".
China is the top pistachio consumer worldwide, with annual consumption of 80,000 tons, while the United States consumes 45,000 tons. Russia (with consumption of 15,000 tons) and India (with consumption of 10,000 tons) are in the third and fourth places.
|Nutritional value per 100 g (3.5 oz)|
|Energy||2,391 kJ (571 kcal)|
|Dietary fiber||10.3 g|
|Vitamin A equiv.||
|Percentages are roughly approximated using US recommendations for adults.
Source: USDA Nutrient Database
The fat profile of pistachios is roughly 14% saturated fat, 54% monounsaturated fat and 32% polyunsaturated fat. A 1-cup serving of pistachio seeds contains 6.143 g (94.80 gr) of saturated palmitic fatty acid, only 0.585 g (9.03 gr) of stearic fatty acid and trace amounts of arachidic and behenic saturated fatty acids.
Toxin and safety concerns
As with other tree seeds, aflatoxin is a toxin found in poorly harvested or processed pistachios. Aflatoxins are potent carcinogenic chemicals produced by molds such as Aspergillus flavus and Aspergillus parasiticus. The mold contamination may occur from soil, poor storage, and spread by pests. High levels of mold growth typically appear as gray to black filament-like growth. It is unsafe to eat mold-infected and aflatoxin-contaminated pistachios. Aflatoxin contamination is a frequent risk, particularly in warmer and humid environments. Food contaminated with aflatoxins has been found as the cause of frequent outbreaks of acute illnesses in parts of the world. In some cases, such as Kenya, this has led to several deaths.
Pistachio shells typically split naturally prior to harvest, with a hull covering the intact seeds. The hull protects the kernel from invasion by molds and insects. But this hull protection can be damaged in the orchard by poor orchard management practices, by birds, or after harvest, which makes it much easier for pistachios to be exposed to contamination. Some pistachios undergo so-called “early split,” wherein both the hull and the shell split. Damage or early splits can lead to aflatoxin contamination. In some cases, a harvest may be treated to keep contamination below strict food safety thresholds; in other cases, an entire batch of pistachios must be destroyed because of aflatoxin contamination. In September 1997, the European Union placed its first ban on pistachio imports from Iran due to high levels of aflatoxin. The ban was lifted in December 1997 after Iran introduced and improved food safety inspections and product quality.
Recycling the shells
Empty pistachio shells can be recycled in several ways. If unsalted, the shells need neither washing nor drying before reuse but washing is simple if this is not the case. Practical uses include as a fire starter, just as crumpled paper is used as kindling; to line the bottom of pots containing houseplants, for drainage and retention of soil for up to two years; as a mulch for shrubs and plants that require acid soils; as a medium for orchids; and as an addition to a compost pile designed for wood items that take longer to decompose than leafy materials, taking up to a year for pistachio shells to decompose unless soil is added to the mix. Shells from salted pistachios can also be placed around the base of plants to deter slugs and snails. Craft uses for the shells include Christmas tree ornaments, jewelry, mosaics, and rattles. Research indicates that pistachio shells may be helpful in cleaning up pollution created by mercury emissions.
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