The growth cycle of pistachios takes seven years, in which a tree's yield is heavy one year and light the next. Pistachio trees in orchards can live for 40 years and produce high-quality nuts up to a ripe old age. The pistachio kernel itself usually develops on the tree in June.  The enlarged nut then pushes against the surrounding shell and causes it to split. The hull, which serves as a protective covering for the nut, remains intact. As the nut ripens, the hull becomes rosy and separates from the shell.

The California pistachios are carefully harvested in autumn. Mechanical "tree shakers" shake the tree trunks until the pistachios fall onto the collection apparatus, thus ensuring they do not come into contact with the ground and can be transferred and processed immediately. This is important as it reduces the growth of mould fungus and aflatoxin.

What is aflatoxin?

In the first processing stage, the pistachio kernels are mechanically removed from the pulp and placed in a water basin. The ripe pistachios sink to the bottom of the basin and are collected. They are first air-dried and then transferred to a silo to dry further. Roughly 10% of pistachios do not split and are removed from the opened nuts then manually or mechanically split and dried for further processing.