Can Pistachios Actually Spontaneously Combust?

When you go shopping for snacks, you have to contemplate each prospective choice. What does it taste like? What is its salt content? When you have one, do you immediately want another? But one question you probably never ask yourself is: "How likely is it that this snack will spontaneously burst into flames?" In most cases, the answer to that question is "zero" — or as close to zero as you can get. But while it's still not exactly likely to happen, the odds are a little bit higher when it comes to pistachios.

What makes these delectable green nuts (which aren't actually botanical nuts, but drupes) susceptible to making like Katniss Everdeen and catching fire? Well, the thing about pistachios is that they're high in fat — and anyone who's ever had to deal with a grease fire can tell you that fat burns really, really well. Usually, pistachios don't contain much moisture, and ideally they stay that way through processing where they're kept in extremely dry conditions. That's because when pistachios spend time in moist conditions, they start to break down, which causes a chain reaction that generates heat. And, if that heat isn't released, or it comes into contact with other flammable elements, it can lead to a fire.

The good news is that flaming pistachios aren't something that you — the casual shopper with a bag of green, salted, roasted nuts in your cupboard — need to worry about. But it is a concern for the people who ship pistachios, whether by truck or boat. The bad news is that, contrary to popular belief, this isn't a phenomenon that's limited to just pistachios. It turns out that since most nuts are high in fat, if they're not stored properly, they can decompose in a way that starts that flammable chain reaction.

Sunflower seeds? They can catch fire. Brazil nuts? They can catch fire, too. And even though the death and rebirth of Mr. Peanut changed us all, peanuts can also create a fire hazard. Of course, this isn't really something that you as the consumer will be forced to confront. But the next time you dip a spoon into a jar of sweet pistachio cream or you make a perfectly imperfect spumoni dessert, take a moment to remember all that went into keeping those nuts from getting overly toasty.