Foam (or Espuma)

Foam is one of the newest members of the foamed dessert club. The method consists of pouring the liquid to be aerated into an iSi siphon, closing the lid tightly, and then filling the canister with one or two charges of CO₂, which will fill the liquid with very small air bubbles. This dispersion of CO₂ that occurs throughout the liquid creates a foam-like consistency that is as light as air. The result is that the liquid will have the same consistency as though it had been whipped by hand or using a mixer. This works for some ingredients that cannot be whipped in the traditional way; the only caveat is that these liquids will require an ingredient that will be able to trap the air bubbles and keep them in place. Heavy cream, for example, contains fat, which is the component that is responsible for trapping air. But other ingredients, such as fruit juices or other liquids that are dairy-free, will require the addition of gelatin in order to trap air bubbles and create a foam.