Harvest and processing

When pistachios become ripe, they are shaken down and then gathered manually from the ground, or they are picked by means of a special machine (only in California) and are directly transported to a mobile reservoir. Nuts must be subsequently shelled and dried in order to keep their high quality and perfect appearance. Nuts are dried in hot air at a temperature between 150 and 160 °C.

Freshly picked nuts contain some 45% of humidity which is reduced to 5% after approximately ten hours of drying. Pistachios are then sorted according to size, quality, colour and shape by means of sorting machines.

Pistachio trees begin to bear their first fruit rather slowly, you can expect the first large production of pistachios roughly after 7 to 10 years after planting. The yields culminate approximately in 20 years. But even now you can see pistachio trees that are forty to fifty years old and still bearing fruit. The climate plays a principal role in the production of pistachios. Pistachio trees require approximately one thousand hours at temperatures around 7 °C necessary for vegetation rest, and necessary for good yields. Mild winter or too frequent rainfalls during the pollinating period may reduce yields.

The processing of pistachios requires a lot of special working procedures and equipment necessary for harvest, handling and production. A great number of growers enter into contracts with customers – pistachio processors who pick and process the crop all by themselves.

The processing procedure begins with transportation of raw nuts to processing warehouses, where they are weighed and provided with a label showing the exact weight and the owner. Pistachios are unloaded and stored temporarily and cleaned by means of flowing air. A sample for quality classification is then taken. Nuts are peeled and peelings are separated for possible later use. The top layer must be removed from picked fruit which must be dried within 24 hours so that shells do not become dirty and possibly contaminated with dangerous aflatoxins. The peel closing nuts is removed by means of machines having two rubber cylinders moving in the opposite directions and rotating at different speeds. Pistachios are then stored in silos depending on their quality and prepared for dispatch.

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