Using liquid nitrogen for ice cream production is a rather dated and adopted technique for many years.
However, the use of liquid nitrogen in the primary freezing of ice cream, which passes from the liquid to the solid state without the use of the conventional ice cream maker, has found a commercial application only in recent times.
In this regard, some rather important technological innovations have been reported in the "National Cryogenic Society Magazine - Cold Facts". The pioneers of this "ice cream revolution" are the companies: Dippin'Dots, Blue Sky Creamery, Project Creamery and Sub Zero Cryo Creamery.
Basically, the technique involves direct contact between liquid nitrogen and the ice cream itself. The latter, quickly immersed and extracted, is then collected in the respective package; producing a blanket of dense white water vapor, the ice cream pack made with just drained hydrogen liquid is very reminiscent of the "witch's cauldron".
In this phase, the ice cream that is still "steaming" is not defined as edible and needs to be left to rest so that the liquid nitrogen vaporizes completely. Sometimes, ice cream is so hard on the outside that it requires a partial thawing.
Compared to the traditional system, making ice cream with liquid nitrogen has some advantages. Thanks to rapid freezing, ice crystals are much smaller and give the ice cream a creamy consistency even with less fat than the original recipe.
Good results can also be obtained with "dry ice", more readily available than liquid nitrogen; some authors like Heston Blumenthal have published some recipes for ice cream and sorbets that can be reproduced with a simple blender.
