The modern pistachio nut was first selected from wild Pistacia vera trees native to central Asia. The initial selection and improvement was first undertaken in the era of the Persian Empire which spanned from Eastern Mediterranean to central Asia. Ever since, pistachios have been an important crop in cooler parts of Iranian plateau.
Pistachio cultivation spread into the Mediterranean world where it has continuously prospered in Syria, Turkey, Greece and Sicily. Pistachios were already well known in Late Antiquity. Since 1970s, pistachios have become a commercial crop in many countries which fall around the 30th parallel north and south of the equator. These regions include: California, North Africa, New South Wales in Australia, South Africa, Argentina and Chile.
Since 1970s, pistachios have developed from a luxury nut appreciated only by the rich into a supermarket item enjoyed by all.
The pistachio of commerce is the only edible species among the 11 species in the genus Pistacia; all are characterized by their ability to exude turpentine or mastic. Several are referred to as pistachios, but the name is generally reserved for the edible nut of commerce. Its Latin name is Pistacia vera L. A member of the family Anacardiaceae, it is related to the cashew, mango, poison ivy and oak, pepper tree and sumac.
The Pistachio is a relatively small tree mostly grown in the arid parts of the world close to 30th parallel latitude. It grows from sea level (e.g. Attica, Greece) to an altitude of 1800 meter above sea level (e.g. Kerman, Iran). The combination of latitude and altitude should provide enough chilling hours in winter and long hot and sunny summer conditions to produce a viable crop.
Pistachios bear laterally on one-year-old wood. This causes an alternate bearing habit, so prominent in pistachio production with extensive commercial consequences.
Pistachio tree is deciduous, i.e. it loses its leaves in the fall and remains dormant through the winter. The tree is dioecious (i.e. two houses), meaning the male flowers are borne on one tree and the female flowers on another. Therefore, both male and female trees are needed for nut production. The pollen is spread by wind.
The trees have extensive root systems allowing them to mine the soil deeply. Thus, pistachios are adapted to survive long periods of drought. They need a well-drained soil. In such soils, the tree can tolerate relatively high levels of salinity in soil and/or irrigation water.
Pistachios are characterized by a long juvenile period, typically bearing few nuts before six years of age. They achieve full bearing between 15 to 20 years of age.
From Pistachio Production Manual
Nut Morphology and Maturation
The individual pistachio nut grows in fruit clusters of multiple nuts, much like grapes. Botanically, they are drupes, the same classification for almonds, peaches, apricots, cherries and plums. All drupes consist of three parts; an exocarp, a fleshy mesocarp (together called hull) and an endocarp (shell) that encloses a seed (kernel). The difference between nuts and fruits lies in the edible portion. In pistachios and almonds the seed is consumed, rather than the mesocarp as in stone fruit.
Ripening of the fruit, late in summer, is signaled by the loosening and separation of hull from the shell and consequent splitting of the shell inside the loosened hull. In reality, not all nuts split open upon ripening. This depends on the cultivar (variety), weather conditions and irrigation schedule.
In all cultivars there exists a genetic aberration that causes shell splitting before hull separation (early splitting). This causes the splitting of the unripe hull which creates access for Aspergillus Flavus spores to the kernel. Such nuts, if not harvested quickly, may provide a good medium for the growth of Aspergillus and the creation of aflatoxin which is a secondary metabolite in the growth of the fungus. The percentage of early splits produced by the tree at the time of the harvest will differ from one variety to the other; it also varies from year to year depending on the weather and irrigation schedule. Early and quick harvest is the best practice in avoiding high levels of contamination by aflatoxin in the harvested crop.
From Pistachio Production Manual
Uses and Nutrition
Naturally split in-shell pistachios are generally sold as salted roasted product. It is the consumer that shells and eats the kernel. Alternatively, a smaller portion of the product is sold as kernels or peeled kernels to the sausage, confectionary and ice cream industry. In the industrial use, kernels are mostly added as an ingredient to give the product an aura of luxury.
Pistachios are a rich source of vitamins and minerals, fiber, antioxidants and œunsaturated fat for a healthy diet. A serving size of pistachios provides more nutrients than most other nuts and snacks:
28 grams of pistachios contains more dietary fiber than half a cup of broccoli or spinach.
28 grams of pistachios contains four times more vitamin B6 than peanut butter.
28 grams of pistachios contains as much thiamin as half a cup of cooked rice.
28 grams of pistachios has the same amount of potassium as a large banana.
28 grams of pistachios has 15 grams of fat, of which only 1.5 grams is saturated. Most of the fat in pistachios is unsaturated, similar to olive oil.
|Serving Size: 100 gr||Energy: 594 kcal|
|Dietary Fiber||1.9 g|
|Fat, Total||56 g|
|Vitamin A||22 µg|
|Thiamin (Vitamin B1)||0.67 mg|
|Vitamin B6||1.7 mg|
|Folate (Vitamin B9)||67 µg|
|Vitamin E||4.6 mg|
Source: Shacker Ardakani, A, “Pistachio Kernel and Its Role in Nutrition and Health” (Ministry of Agriculture, Agricultural Research and Education Organization, Iran Pistachio Research Institute, 2006)
Health Benefits of Pistachios
There have been numerous studies highlighting the health benefits of pistachios:
FDA published a statement in 2003 approving that scientific evidence suggests that eating 1.5 ounces per day of pistachios, as part of a dietlow in saturated fat and cholesterol, may reduce the risk of heart disease. Pistachios may help curb less-than-ideal levels of LDL “bad”cholesterol, according to another study published in 2008. In research at Pennsylvania State University, pistachios in particular significantly reduced levels of low-density lipoprotein (LDL cholesterol) while increasing antioxidant levels in the serum of volunteers.
Reducing Risk of Lung Cancer
According to data presented at the American Association for Cancer Research Frontiers in Cancer Prevention Research Conference, a diet that incorporates a daily dose of pistachios may help reduce the risk of lung cancer.According to the research, pistachios are a good source of gamma-Tocopherol, which is a form of vitamin E, and it is known that vitamin E provides a degree of protection against certain forms of cancer. Therefore it is thought that eating pistachios increases the intake of gamma-Tocopherol, so pistachios may help to decrease lung cancer risk.
Research published in Molecular Nutrition & Food Research shows that pistachio oil decreases levels of an inflammatory marker known as “Ifit-2”. Inflammation is a biological response to harmful stimuli, pathogens, damaged cells or irritants, and it underlies functional changes associated with many chronic diseases, such as obesity and cancer. The finding that pistachios decrease inflammation, a newly discovered risk factor, for cardiovascular disease as well as other diseases is further support for the key nutrition message about including pistachios in a healthy diet for chronic disease risk reduction.
In December 2008, Dr. James Painter, a behavioral eating expert professor and chair of School of Family and Consumer Sciences at Eastern Illinois University, described the Pistachio Principle. The Pistachio Principle describes methods of “fooling” one’s body into eating less. One example used is that the act of de-shelling and eating pistachios one by one slows one’s consumption allowing one to feel full faster after having eaten less.
Why Iranian pistachios
Iranian pistachios offer various advantages that set them apart from competitors. Greater choice is offered to customers through four main commercial varieties. Additionally, higher meat content offers better value for money. Iranian pistachios have a world-famous taste that is unrivalled. This taste advantage is enhanced by roasting Iranian pistachios at higher temperatures, made possible by higher unsaturated oil content. This high temperature roasting eliminates any bacterial contamination, which may be present in raw product. The following list details the five major advantages of Iranian pistachios:
Variety There are many different varieties (cultivars) of Iranian pistachios. The following four go into international trade: Fandoghi (40% of pistachio orchards), Kalleh-Ghouchi (20%), Akbari (15%) and Ahmad-Aghaei (12%), with the last two on the rise. Each variety has its own differing properties and flavor.
Higher Kernel to In-Shell Ratio Iranian pistachios have a high kernel to in-shell ratio, meaning you are buying a higher amount of the edible kernels for the same amount of pistachios you buy.
Roastability Due to their higher unsaturated oil content, Iranian pistachios have the capacity to be roasted at between 160 to 180°C (hot air stream temperature). Good roasting brings out the unique flavor of the nut, while eliminating any live bacteria from the roasted product. It is obvious that lower roasting temperatures of around 120°C recommended by some suppliers will not achieve the two above benefits.
Taste Over a long period, consumers around the world have shown a preference for the taste of Iranian pistachios. All four commercial varieties of Iranian pistachios each have a rich, unique and distinctive flavor. In this regard, Iranian pistachios offer a combination of unparalleled flavors which gives the consumer choice and variety.
Tradability The large number of producers, buyers, exporters and importers of Iranian pistachios makes for conditions of perfect competition in the market. As a result, fairer trading opportunities present themselves to those engaged in buying and selling Iranian pistachios. In the absence of conditions of perfect competition, the market may face price fixing and market manipulation by influential players.
The Iranian Pistachio Industry
The pistachio industry in Iran is made up of three main sectors: farming, post harvest processing and trade; each is explained in more detail below:
Due to the botanical characteristics of the pistachio tree, there are limited geographical locations on the planet with favorable climatic conditions for economically-viable pistachio production. Pistachios have been cultivated in Iran for thousands of years. Commercial cultivation of pistachios in Iran started expanding about one hundred years ago. The upward trend of production has continued ever since.
It is estimated that the amount of pistachios produced in Iran rose from around 2,000 tons in 1950s to about 25,000 tons in 1975. The average nationwide production in the closing years of the millennium exceeded 150,000 tons.
At present, around 150,000 farmers harvest the crop from about 290,000 hectares of pistachio orchards nationwide; more than 70% of the production is coming from small scale producers (those who manage orchards of 2 hectares or less). Currently, annual pistachio production capacity in an “on” year is up to 280,000 metric tons. This is from orchards in Kerman, Yazd, Khorasan, Fars, Semnan, Markazi and some other provinces. Despite its declining role due to a province-wide water shortage, Kerman will still have the dominant share of orchards and production for the coming decade. It should be noted that the decline in Kerman™s production is more than compensated by the production increase in other provinces.
All pistachio orchards in Iran are hand-harvested. Average annual yield of bearing Iranian pistachio orchards is 800 kg per hectare. Individual farms may produce from 300 to 3000 kg per hectare. The gradual decrease in yield of pistachio orchards in Iran is mainly caused by a severe decrease in the quantity and quality of irrigation water coming from deep wells. This malaise results from over-issuance of government permits to bore deep wells in a diminishing aquifer. The problem is exasperated by the breaking up of the orchards to smaller units resulting from inheritance laws.
It is hoped that new plantings in areas with abundant water resources by corporations rather than individuals would, in future, open the way for establishment of modern, industrial scale orchards. Iran Pistachio Association is already promoting such initiatives through the Model Pistachio Orchard Project.
Post Harvest Processing
The pistachio processing industry in Iran is gradually moving from traditional, low-capacity, home or farm based, sun-drying units towards specialized, industrial high-capacity plants utilizing hot forced air for drying. Traditionally, processing plants acted as service providers to the growers. Therefore, each grower retained possession of his/her produce after processing. However, with the advent of new industrial processing plants and the rising costs of processing in small scale units, new collective processing agreements are becoming more popular. In such schemes, the processing unit may even make the decisions about the selling of the processed pistachios on behalf of the growers.
Currently, the largest industrial pistachio processing plant in the country has a capacity of 350 tons of fresh pistachios per day. Although the number of high-capacity plants is small, the total number of mechanized processing units is quite large and growing every year.
A typical modern Iranian pistachio processing plant processes freshly harvested pistachios as follows:
Weighing, unloading and sampling: The trucks loaded with freshly harvested pistachios are weighed prior to and after unloading to get the net weight of the pistachios. The pistachios are unloaded into unloading bays (where samples are taken randomly), and are then moved onto conveyor belts to start the processing phase.
Hulling: Fully mechanized dry-operated rotating hulling machines remove the outer hull of the pistachios. The pistachios continue to the next step, while the removed hulls and other debris are rejected from the main product stream.
Water floatation tank: Blank nuts and nuts with immature kernels are removed from the main product stream when the pistachios are passed through a floatation tank. The underweight and blank pistachios (floaters) float to the top while the larger, heavier pistachios (sinkers) sink to the bottom.
Heated, forced air continuous pre-drying: The pistachios pass through a high-temperature pre-dryer, where the surface moisture added in the previous stage is removed and as a result, the next stage machine for removing nuts with adhering hull can operate more efficiently.
Adhering hull separation and removal: The pistachios drop over a large diameter roller, where pistachios with adhering hull are removed from the product steam through differential friction. These pistachios with adhering hull are returned to the beginning of the line for re-hulling.
Dryer and sun drying: Using batch or continuous forced-hot-air dryers, the pistachios are heated to reduce the moisture content to 7-11%. Then the pistachios are dried in the sun or by forced-ambient-air ventilation to reduce the moisture content to less than 5%.
Mechanical separation of open-shell nuts from closed-shell nuts: Open-shell nuts are separated and move to the next stage (closed-shell nuts are processed separately).
Mechanical sizing: The pistachios are separated into two or three grades depending on size.
Picking conveyor belt and/or picking table: The nuts with visible defects are removed.
Packing: The pistachios are packed in 50 kg sacks ready for transport or storage. Recently, there is a trend towards packing pistachios in big-bags.
Iran is the largest net-exporter of pistachios in the world with an average annual amount of 160,000 tons (dry basis) and an estimated current grand total value of around USD 1.5 billion. This amounts to more than 60% of the world net-export figures. Most pistachio exports are in bulk: raw dried pistachios, roasted pistachios, pistachio kernels and green peeled pistachio kernels. The main consumer markets for Iranian pistachios are the Far East, the European Union, CIS countries, the Middle East and the Indian subcontinent in that order. However, the market trend for Iranian pistachios is shifting from affluent countries towards an increasing number of developing countries. Pistachios are exported according the buyers’ requirements and standards, provided they meet the minimum Iranian national standards.
There are tens of export houses in Iran. Of this number, some are dedicated pistachio exporters, while others export other dried agricultural commodities in addition to pistachios. These established exporters, as a group, command about 95% of total Iranian pistachio exports. There are also a group of exporters that are generally of much smaller size, but varying in number from year to year, who will export on a sporadic basis, depending on the immediate profitability of the export of pistachios compared to all other exportable goods.
The domestic trade in pistachios is conducted exclusively by local traders who assemble pistachios, bought from small to medium sized producers, into lots of from tens to hundreds of tons. The bigger exporters buy their needs from such traders, whereas, exporters who focus on quality mainly buy from medium to large farmers or processors.
Growers of pistachios, especially the medium to large sized ones, can and often do, sell their products directly to the established pistachio export houses. Such transactions are usually facilitated by either professional pistachio brokers, or commission agents. This particular avenue of export provides a unique opportunity for product traceability from the hands of the international consumer, back to the producing orchard in Iran.
The large number of producers, buyers, exporters and importers of Iranian pistachio makes for conditions of perfect competition in its trade. This creates a fairer trading environment for those engaged in buying and selling Iranian pistachios.
Minimizing Aflatoxin Contamination Risks
Aflatoxins are naturally occurring mycotoxins (toxic secondary metabolite of molds) that are produced by some strains of Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are toxic and among the most carcinogenic substances known.
Aflatoxin-producing members of Aspergillus are common and widespread in nature. Host crops are particularly susceptible to infection by Aspergillus following prolonged exposure to a high humidity environment or damage from stressful conditions such as drought, a condition which lowers the barrier to entry.
Aspergillus is commonly found in soil and their spores are transported by air. Decaying vegetation, hay, and grains undergoing microbiological deterioration can be an ideal media for the propagation of the fungus. It afflicts many crops on the farms, including corn, rice, cotton seed, peanuts, figs and all tree nuts such as pistachios.
In pistachios, aflatoxin mostly occurs on the farms just prior to harvest. Therefore, they can best be avoided by timely and speedy harvest.
The Iranian pistachio industry is attempting to minimizie the risk of aflatoxin contamination through the following measures:
- Observing GAP in the orchards
- Timely and speedy harvest
- Industrial scale fresh pistachio processing utilizing high capacity forced-hot-air dryers
- Use of water floatation tanks to remove high risk pistachios from the product stream
- Manual sorting of dried pistachios to remove nuts with shell or kernel defects
- Observing GMP in fresh and dry processing plants
- Observing sanitary guidelines during warehousing and transport
- Supporting research projects for understanding the nature and cause of alflatoxin contamination in different sections of the pistachio industry and finding ways for its elimination.
Iranian Pistachio Varieties
There are tens of varieties of pistachios developed by curious Iranian farmers, on a small scale. Every decade or two one of these varieties has been developed and has been seen as advantageous in certain aspects, so it has been taken up by other farmers. Some of these varieties have endured enough to become stable commercial varieties. In general, all commercial varieties of Iranian pistachios fall into two categories by shape: round and long. A pistachio type is called long if the ratio of the length to the greatest diameter is more than 1.5, otherwise it is called round. The original wild Pistacia vera trees produced nuts of the long type. The first round variety was developed by a farmer from Rafsanjan named Mr. Ohadi some 70 years ago. Some earlier commercial varieties, such as Sefid Peste and Momtaz, have gone out of fashion and are not budded anymore.
Today, there are four different commercial varieties of pistachios cultivated in Iran, which have differing characteristics and properties as listed below:
Fandoghi: This cultivar is the most widely available pistachio variety and grows in most pistachio growing areas of Iran. Fandoghi is of round type and has the lowest shape index among the four cultivars. It comes in the following sizes 28/30, 30/32 and 32/34 nuts per ounce. Size 26/28 is also available in small quantiti
Kalleh Ghouchi (Jumbo): This type of pistachio tree has a good yield and the nuts are of round type. Sizes are 20/22, 22/24 and 24/26, with 18/20 being available in small quantities.
Akbari: This is a newer variety with good yield and with long, large nuts (sizes: 20/22, 22-24 and 24/26, with 18/20 also available in small quantities). It has the highest shape index (longest). Its the most easy-to-open pistachio variety among the four.
Ahmad Aghaei: The newest commercial variety, very popular with the farmers, because of high yield and its shorter time to reach production. It is very popular in some markets like India and Greece. Production of this variety is increasing. The appearance of Ahmad Aghaei pistachio resembles the Kerman variety of US pistachios. It also has the whitest shell hue among the four. Ahmad Aghaei is a long pistachio type, with the shape index just falling above 1.5. It comes in sizes 22/24, 24/26, 26/28 and 28/30, with 20/22 being available in small quantities.
On the whole Kalleh Ghouchi is not being budded anymore and production is from existing trees. Although commercially quite successful, Kalleh Ghouchi trees showed a steep drop in growth and production as they grew older than 40 years old. It is expected that the production would slowly decline.
At present, probably around 50% of Iranian production is of the Fandoghi type. Due to its limited yield, the new orchards are seldom planted with this variety. It is expected that the production will stabilize at present levels. Kalleh Ghouchi is on the decline being replaced by Ahmad Aghaei. Newer orchards are being budded with Ahmad Aghaei or Akbari varieties. In the future, more of these two varieties are expected to be available in the market.