I’ve got a confession to make: I do some science stuff. I do them daily.
I was 10 years old or so when I decided that I would be a scientist.
That dream turned out into many years of study and days spent in the lab looking for answers and collecting questions, instead. Now on a bad day I ask myself: “What have I done?” ; a good day I mutter “I’ve done something interesting, this time. But what, what the heck have I done?”
On a fantastic/phantasmagorical day I am in Canada for research purposes and my fellow scientists take a chance on liquid nitrogen, the one I typically employ to cool down my light detector, to fulfill a more noble cause: liquid nitrogen ice cream. Oh yeah. The real taste of science.
Nitrogen is a chemical element that comprises 79% of the atmosphere. It is a gas but can be reduced to the liquid state by compression and thus transported as a liquid in vacuum flasks. See the white vapor it produces when exposed to the air? Liquid nitrogen when released, absorbs large amounts of heat and evaporates instantaneously.
Because of its very low boiling point (77.35 K corresponding to -195.82 °C), it can be used as powerful refrigerant, as a coolant for computers, in medicine to remove pre-cancerous cells and in cryogenics with plenty of scientific applications. In my lab experiments I use it to study the effect of very cold temperatures on materials.
Cooking with liquid nitrogen may sound odd and eccentric to you, however the idea of using liquid nitrogen in food is not actually new and different uses in the kitchen are now in the context of cutting-edge restaurant industry.
First came chef Heston Blumenthal, who prepared nitro-scrambled egg and nitro-poached aperitifs at his Berkshire restaurant, The Fat Duck. Over the last few years many other chefs began to serve instant ice creams in front of their customers, mostly to impress them with the cloud of vapor that the liquid rapidly emits while boiling away.
Doesn’t this sound cool? As cool as -196 °C can be. A little too cool to be ordinarily used in our kitchens. Liquid nitrogen is colorless and tasteless, not an ingredient but a powerful refrigerant. As such it is NOT completely risk-free.
And now we come to those safety issues that scientists love to speak about to impress people and cause a resonant, admiring (scared) WOW.
You don’t really want to ingest a drop of liquid nitrogen. Because of its low temperature, it may cause burns and tissue necrosis. Let me be forthright: if you dip a hand in liquid nitrogen you will risk of losing it. Tissues will lose elasticity and break as if they were made of glass.
Clear enough? On the other hand the use of liquid nitrogen in the food preparation is perfectly safe if you:
Make sure that all the liquid has evaporated before food and drink prepared with liquid nitrogen are ingested;
Wear appropriate gloves;
Do not to wear open shoes and handle the container so to avoid any spill.
We use liquid nitrogen in the lab pretty often and still value all the safety precautions (I wish I knew where the gloves are).
Here below is a list of all the materials we used to prepare our ice cream.
Large stainless steel pot. The pot needs to be resistant to the cold temperatures of liquid nitrogen.
Long wooden spoon for stirring.
Measuring cup and spoons for sugar and vanilla.
5 liter container of liquid nitrogen.
Bowls to serve (we used Styrofoam cups).
Science aside, don’t you want to know how a liquid nitrogen ice cream tastes like?
The ice cream we prepared according to the recipe of Professor Stephen Thornton of University of Virginia, had a lovely velvety texture, a particular softness conferred by tiny ice crystals, smaller than those produced during the traditional freezing procedures. A real treat. Maybe a little geeky but still a treat.