Let me start here: this was not one of the best ideas I've ever had! I was preparing for "The Science Spot" a short science bit I do for the local CBS station and was deciding what liquid nitrogen demonstrations I should perform on tv. I stopped at the grocery store and decided to fill up the cart with Twinkies, Oreos, Snoballs and Oatmeal Creme Pies. I filled up a Dewar (liquid nitrogen container) and proceeded to freeze snack foods...and eat them.
Liquid nitrogen is -321 degrees Fahrenheit (-196 degrees Celsius) and when it is exposed to air it begins to vaporize or boil (turn to a gas) because anything above -320 deg F that will cause it to turn from liquid to gas. When the snack foods are placed inside a few things happen. The liquid nitrogen fills the voids in the food and, once the food is cold enough, remains liquid inside the spaces between the food particles. At the same time, the water inside the food freezes causing ice crystals to form. If left inside the nitrogen long enough, the water will sublimate (turn from solid to gas) causing the food to dehydrate.
When I eat the food, the liquid nitrogen quickly turns to nitrogen gas and leaves a brief fog behind, much of which is actually water vapor that is briefly condensing because of the cold nitrogen air. The only thing that keeps my tongue and mouth from being frost-bitten or frozen is the physics of the nitrogen gas turning from liquid to vapor. As it vaporized, a small area around the drop of nitrogen turns to a gas layer, effectively keeping my skin from coming into direct contact with the liquid.
But, let's make one thing clear - this is NOT A GOOD IDEA and you should not try it at home. It could severely harm you if left in your mouth too long or if swallowed, not to mention the damage it could cause to your teeth or eyes or...well, any of your body parts!
Now, if only I would take my own advice.....
Craig Beals takes liquid nitrogen to CBS Q2 for "The Science Spot"
Equipment needed to safely handle liquid nitrogen
Dewar (container for transporting and storing liquid nitrogen)
Safety Goggles (these are a Beals Science favorite)
Where to buy liquid nitrogen?
Liquid nitrogen can be purchased at any industrial gas supplier or medical gas supplier. You may have to do some searching in your area but these suppliers usually carry oxygen gas for medical use, acetylene gas for welding and liquid nitrogen for medical and agricultural uses. The container you need to carry liquid nitrogen is called a Dewar (find one here) which are quite expensive. Most places will not sell you liquid nitrogen if you don't have a Dewar although some suppliers will rent or loan you one.
How much does liquid nitrogen cost?
Liquid nitrogen is sold by the liter (or gallon) and varies from $0.10 (US Dollars) for bulk purchases up to $5.00 per liter for a small Dewar.
Is liquid nitrogen dangerous?
Yes. It can be very dangerous. Liquid nitrogen is -320 degrees F (-195.75 degrees C) so it can cause frostbite on skin very quickly and can damage eyes, nose, mouth and internal organs on contact. Liquid nitrogen also evaporates very quickly and the ensuing gas takes up more space than the liquid. If the liquid is left in a container that cannot vent off this gas, pressure builds up and a pressure explosion can occur - this is why only an approved Dewar container with a pressure valve and loose lid can be used to transport consumer Liquid Nitrogen.
Want to see more foods soaked in liquid nitrogen?
Check out "Liquid Nitrogen Cereal and Donuts"!
Keep on Learning! ~Craig