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 until recently. It is estimated that the amount of pistachios produced in Iran rose from around 2,000 tons of dried in-shell nuts in the 1930s to about 200,000 tons at present. The record estimated amount of annual production has been 267,000 tons.
All pistachio orchards in Iran are hand-harvested. Average annual yield of bearing pistachio orchards is 600 kg of hulled and dried in-shell nuts per hectare. Individual farms may produce from 200 to 5000 kg per hectare.
The gradual decrease in the 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. The problem is intensified by the breaking up of orchards into smaller units due to inheritance laws. It is hoped that new plantings by corporations rather than individuals in areas with better water resources would, in future, open the way for the establishment of modern, industrial-scale orchards. Furthermore, collective decision making schemes at the farm level by neighboring small farmers sharing a single water-well, may prove to be another solution to the breakup of orchards into smaller units. Iran Pistachio Association has been promoting such initiatives.
The pistachio processing industry in Iran is gradually moving from low-capacity home-based units towards industrial high-capacity plants. Some processing plants act as service providers to growers with each grower retaining possession of his or 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, an industrial processing unit may make the decisions about the sale of processed pistachios on behalf of individual growers. Currently, the largest industrial fresh pistachio processing plant in the country has a capacity of 400 tons of fresh pistachios, equivalent to 130 tons dried-inshell, per day. Although the number of high-capacity plants is small, the total number of mechanized processing units is 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.
Pistachios have been exported by Iranians from several hundred years ago. The export volume had a quantum leap with the advent of commercial pistachio orchard establishment in the early 20th century.
Currently, Iran exports an annual average volume of 160,000 (one hundred and sixty thousand) tons of pistachios (dried in-shell basis). Iran is one of the two major global pistachio exporters besides the US. Most pistachio exports are raw, in bulk, in one of the three following forms: dried in-shell pistachios, pistachio kernels, and green peeled pistachio kernels (also known as GPPK). The main consumer markets for Iranian pistachios, in order of export volume, are the Far East, the European Union, the Indian subcontinent, Middle East and CIS countries. However, the market trend for Iranian pistachios is shifting from affluent countries towards an increasing number of developing countries.
There are more than a hundred pistachio 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 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 from a few to hundreds of tons in volume. The bigger exporters buy from such traders, or from medium to large farmers or processors, directly.
Growers of pistachios, especially the medium to large sized ones, can sell their products directly to the established pistachio export houses. Such transactions are usually facilitated by either professional pistachio brokers or commission agents. From around 15 years ago, with fading away of Rafsanjan Pistachio Producers Cooperative (better known as RPPC), the large number of independent producers, buyers, exporters, and importers has created perfect competition conditions in the markets for Iranian pistachios. This has resulted in a fairer trading environment for those engaged in buying and selling Iranian pistachios. Given this competitive trading structure, one should note that it would be impossible to have fixed industry-wide opening prices for Iranian pistachios in any crop season.
Minimizing Aflatoxin Contamination Risks
Aflatoxins are naturally occurring mycotoxins (the 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, cottonseed, 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 minimize 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 aflatoxin contamination in different sections of the pistachio industry and finding ways for its elimination.