When pistachio nuts explode

Laptops and humans aren't the only things that can spontaneously combust. Pistachios are so likely to burst into flames that there are strict shipping codes to keep them from doing so.

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Next time you're slurping some pistachio ice cream (Although why would you when there are sane flavors like chocolate and pumpkin?) be aware of the terrible price of your treat. For you, sure, it's cool and wet (And creepily green. What's that about?) but unprocessed pistachios are dangerous. Under the right conditions, they've been known to heat enough that they spontaneously combust. In fact, ships have a host of conditions they have to meet when they transport pistachios to keep them from going kablooey (That's a nautical term, landlubbers.).

In fact there seem to be no end to the ways pistachios can kill. Just having them in an enclosed space can suffocate someone. They take in oxygen and excrete carbon dioxide, even after they've been harvested. Ships have to keep them in a well-ventilated place so they don't suck all the air out of a place and suffocate cabin boys.


They also have to be kept under the right temperature and pressure conditions. Pistachios have a low water content and a high fat content. Water doesn't burn. Fat does. There may seem like a logical solution to this. Ships go over oceans, lakes, and rivers, so the humidity should bring up the water content and everything should be okay, right? Arh, ye be wrong, me lads.

When the water content in pistachios gets too large, fat-cleaving enzymes kick in. The fat-cleaving enzymes produce free fatty acids, and those fatty acids are broken down when the nut takes in oxygen and spits out carbon dioxide. During that process it also spits out water, which makes more fat-cleaving enzymes kick in. What's more, that process of breaking down the fatty acid, taking in oxygen and putting out carbon dioxide has a more common name; burning. The process gives off a lot of heat, and that heat builds and builds until the entire bunch of nuts catches fire and sometimes explodes.


Because of this danger pistachios, and other nuts, need to be kept at just the right temperature, pressure and humidity on ocean voyages. Otherwise, it's to davy jones' locker with all of ye. And there be no pistachio ice cream there.

Via the Transport Information Service, Container Handbook and Gothamist.


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