Foams — stable or transient aerated preparations — became the defining visual element of modernist cuisine through Adrià's espuma technique (flavoured liquid charged with N₂O in an iSi siphon). Modernist Cuisine distinguishes between transient foams (unstable, produced by whipping) and stable foams (produced with lecithin, methylcellulose, or other hydrocolloids). The culinary value of a foam is the delivery of intense, concentrated flavour in an extremely low-density format — the palate receives maximum flavour compounds with minimal physical mass.
**Espuma (N₂O siphon foam):** - Any liquid can be charged in an iSi siphon - Cream-based: the cream's fat stabilises the foam naturally - Non-fat liquids: require a stabiliser (xanthan, lecithin, agar) to maintain the foam structure after dispensing - The N₂O dissolves in the liquid under pressure; when dispensed, the gas expands and creates the foam **Lecithin air:** - Blend lecithin into a flavoured liquid at 0.3–0.5% - Use an immersion blender at the surface to incorporate air - Produces a light, unstable foam with pure, intense flavour — best served immediately
Modernist Cuisine Vol. 4