Pistachio preservation implies a longer shelf life to generate more revenue. In fact, long term preservation of pistachio in warehouses is key in the industry. This goal, however, has obstacles.
There is a higher threat of aflatoxins in the preservation of pistachios than in other nuts. On the other hand, pistachios are less susceptible to oxidative rancidity compared to other nuts, apparently due to their having a smaller unsaturated to saturated fatty acids ratio.
The Food and Drug Administration (FDA) has established distinct “safe moisture levels”. The moisture content which will not support fungal growth is about 7%.
Once dried to 4–6% moisture, pistachios can be held at 68°F and 65-70% relative humidity for up to one year.
Other factors that enhance nut quality in storage are exclusion of oxygen and insect control through fumigation, controlled atmosphere (CA), lowered temperature in storage bins, and insect-proof packaging.
A hermetic flexible package solution will preserve pistachios when storage conditions are imperfect with regards to temperature and humidity, and consequently lengthen shelf life by more than one year.
Studies also demonstrate that staining of pistachio nut shells increases with temperature and extended holding times, and so this is especially important logistically. The solution is artificially cooling the goods during transport.
VacQPack is more efficient, partly because of its ability to preserve in higher storage temperature conditions (>75ºF). Previously, increase in temperature during storage meant reduction of taste, low fruit firmness, kernel damage, water loss, and increased acidity and peroxide. Now, with VacQPack, higher temperatures are welcome to fight insect infestations and prove to not be detrimental with regard to the aforementioned factors.
Several insect pests attack the pistachio kernel, like the pistachio seed wasp (Eurytoma plotnikovi) and the Carob moth (Apomyelois ceratoniae), causing necrotic lesions on the hull kernel (stigmatomycosis).