At the beginning of the MC project, Nathan set out to dispel many of the myths surrounding cooking, yet some common misconceptions about liquid nitrogen still persist. Sometimes we get questions like Is liquid nitrogen dangerous? Will it hurt you? Or, You can’t cook with liquid nitrogen! It’s poisonous!
The truth is, liquid nitrogen is completely inert except for its extreme temperature. It will cause any metal it comes in contact with to become freezing cold, but wearing dry gloves is enough to protect your hands from creating a “tongue stuck to the flagpole” scenario. The liquid nitrogen itself will evaporate before it contacts your skin due to the Leidenfrost effect (see video below).
Actually, liquid nitrogen pales in comparison to the dangers involved in most applications of fryer oil or even sugar. Fryer oil is extremely hot; it spills, it splatters, it splashes. Any cook who works frequently with deep fat fryers gets burned all the time. You get little blisters on your arms and hands when heating oil. The day we shot our wok cutaway photo, Max got all sorts of burns on his arms from tossing the phad Thai and oil so many times.
When it comes to kitchen burns, sugar is enemy number one. Anyone who has had a close encounter with hot caramel knows that you really don’t want this stuff on your skin. If a little bit of the hot caramelized sugar lands on your hand, your first reaction is to rub it, which leads you to smear it onto your other hand. It just sticks everywhere, and you end up burned all over.
I’ve been working with liquid nitrogen in the kitchen for about five years now. I’ve dipped my bare hands in it, spilled it, splashed it, but never been hurt by it. I’m not saying you should go ahead and goof around with it, but you should give it a chance without fear. Go ahead and try it! It’s great for all sorts of applications. Just put on gloves, wear long pants so that it can’t drip into your shoes if you spill any, and don’t eat food until you’re sure the nitrogen has boiled off of it. (For a more complete discussion, see “Safe Handling of Cryogens,” page 2·464-466 in Modernist Cuisine.)
A number of recipes in Modernist Cuisine use liquid nitrogen to achieve special effects, from firm coating gels to foie gras torchon, from shrimp and grits to buttermilk biscuits. And, of course, we love Nathan’s method of cryofrying meat, which is to cook meat sous vide, then dip it in liquid nitrogen, and finally deep-fry it quickly to get a really nice, Maillardized outer crust with a rare or medium-rare interior. We use this technique in our mushroom cheeseburger recipe. And again, it’s really the hot oil from the deep fryer that you have to watch out for in that recipe.
Although it’s not hard to handle liquid nitrogen safely, it is also not completely without risk. In fact, I just happen to be one of the few people in the world who have actually had a traumatic experience with the substance. I once used liquid nitrogen at a dinner for some guests and afterward was transporting a Dewar of the stuff in the back of my SUV. Although the Dewar was in perfect condition, some of the dinner guests had been playing with it and hadn’t refastened the lid. I didn’t realize that, and as I was heading up a hill, the Dewar fell over. Liquid nitrogen has a very low viscosity, so it is thinner than water and flows like crazy. It quickly spread all over the bottom of the car, and as it boiled off furiously, the car rapidly filled with vapor. It also got really cold, and I couldn’t see out of my rear view mirror or rear window. It was like driving through the densest fog–but the fog was inside the car!
I pulled over and got out of the car as fast as I could. As the nitrogen evaporates into gas, it displaces oxygen in the air, so if a lot of it spills in an enclosed space it can create a suffocation risk. Emerging from the car, I looked back and saw white fog pouring out from every opening. Luckily, our photographer, Ryan Matthew Smith, was behind me and also pulled over. We opened the hatch of the SUV to get the Dewar out, in case it was still leaking. I heard the plastic in the car crackling as it warped from the intense cold.
When it was all over, I was surprised to find that despite the large size of the spill, it didn’t cause any permanent damage. If the Dewar had been filled with super-hot fryer oil instead of ultra-cold liquid nitrogen, it would have been a different story.