This steaming, freezing dish is being served in more and more restaurants as of late. And while it may look like something from science class, it’s little more than a classic – but excellent – ice cream, with a bit of scientific tweaking. The good news is that it can be easily – and inexpensively – prepared at home.
One should first understand, however, what makes up ice cream. Ice cream is a mix of elements that cannot combine together among themselves, but that form a single mass composed of ice crystals, fat, air bubbles and a solution of water, sugar and flavors. Among these elements, the one that is responsible for creating “the magic” of ice cream, is the ice – whose crystals vary between 1 and 20 microns in size: the smaller the crystals, the creamier the ice cream. Larger crystals contain more water and tend to dilute the flavor. Crystal size depends on many factors, but the main two are temperature and the freezing time. If you want a velvety, smooth ice cream, it needs to be kept at a very low temperature, which allows it to freeze in just a matter of seconds.
And this is where the liquid nitrogen comes in: it’s a substance that reaches temperatures as low as -196° C – so cold that it can freeze just about any food. The only “problem”, is that liquid nitrogen is hard to conserve, which is why it needs to be kept in a cryogenic container, which can be costly. But just a liter of liquid nitrogen, which costs just a few dollars, is enough to conserve more than 2 kilos of ice cream. You can either buy a Dewar vacuum (which will cost around $250), or either something smaller which will suffice for making ice cream in household quantities. There are many options for kits to be found online, which are indispensible for creating homemade ice cream with this impressive, irresistible and simple technique.
At this point, let your imagination run wild. All you need for ice cream is a simple fruit and sugar mixture, but the taste will improve with a bit of added fats: chocolate or coffee are excellent ingredients for the novice. When you add the liquid nitrogen, add just a little bit at a time and then stir: usually one minute for each liter will be enough. While liquid nitrogen is safe for eating and is a harmless substance, you shouldn’t leave your hands in there for too long, as you may get a “freezer burn”. But just keep these simple safety measures and scientific in mind and remember to get creative (try savory flavors!) – and you’ll be making a gourmet worthy, ice-creamy dessert in no time.