foam

Also known as “sweetened egg white foam”,“egg white foam”. In the context of mixed drinks, the “foams” we are referring to are protein-based emulsion produced from egg whites or another protein source that is either whipped or charged with compressed gas to create a light, semi-stable closed-cell foam. Historically, the foams produced for drinks were hand-whipped meringues. Today, it is more typical to employ an N2O charger with egg whites, an acid, and a sugar-based sweetener, both of which fulfill chemistry-related purposes. A starting recipe [Jamie Boudreau, “How to make cocktail foam”, Small Screen Network] for an N2O-based foam would be 4 egg whites, 6 oz of the liqueur or syrup of your choice, 3 oz lemon juice, and ~2 oz water (if needed to stretch the flavor a little). This mixture would be double-charged in an isi cream whipper (or similar) and chilled before use. The ideal proportions may vary depending on how much sugar is included in your sweetener as well as how much alcohol it contains.