Pistachio Processing Operations
Almost all of the procedures in the pistachio processing operation are handled by machinery and through a production line. The nuts can be harvested manually or mechanically. The advantage of manual picking is that each single nut can be examined and appraised. Unsound and infested nuts are recognized and sorted out. The advantage of the mechanical harvest is the speed.Once harvest is underway the pistachios are taken off the trees around the clock and immediately processed to minimize the risk of Aflatoxin. Aflatoxin is a metabolic product of the mould fungus which develops in connection with dirt and moisture over a certain period. Taking this fact into consideration, it is absolutely important that the pistachios do not get in contact with the soil during the harvest and that long interim storage is avoided.
After the pistachios are peeled, the nuts go through a washing cycle.
The goal of this phase is to separate the immature and damaged nuts having low weights by means of having the pistachios float in the water. The healthy and heavier pistachios are collected at the bottom of the water tank.
The good quality pistachios and the lower quality ones are separated.
In this phase the excess moisture is removed from the product.
Before the pistachios enter the dryers, the remaining paltry and unwanted parts including nuts with improper colors and unpeeled nuts are removed.
Hot air heating machines are used to dry pistachios. These machines make it possible to dry the pistachios quickly and without contamination. The duration of the drying process depends on the temperature, speed of airflow, and depth of the pistachio pile.
Pistachios are then stored in silos and cooled.
At this stage, naturally open-mouth pistachio nuts are separated from closed-mouth ones.
Open-mouth pistachios are sorted at this stage for size and quality and then stored for future shipment. Workers handle the final stage manually where the pistachios are packaged for shipment.
These pistachios serve three very different purposes:
1- They are packed and shipped as they are for the final buyer to process them as they please in their own facilities.
2- They are mechanically opened and sold as a lower quality pistachio.
3- Pistachio kernels and green kernels. By mechanically opening of the closed-mouth pistachios and the peeling of the hard shell we get pistachio kernels, and by double peeling we get the green kernels.
Roasting of pistachios is done to each customer’s requirements by a separate production line.
Raw or roasted pistachios are packed in 50 kg double PP bags.
Pistachio kernels and green kernels are packed in 10 kg plastic bags and then into a cardboard box.