The Complete Handbook of Frosting & Icing

Chapter 1: Understanding Frosting & Icing

1. Understanding Frosting & Icing: What It Is, How It Works, Why It Matters

Any frosting or icing is, at its core, an engineered suspension of solids and liquids intended to sit on top of a baked good and do one of three things: protect the crumb from drying out, add flavor and richness, or carry a visual design. Every single formulation in commercial use, from the thin glaze on a glazed donut to the sculpted sugar paste on a wedding cake, is a balance of the same basic ingredients: fat, sugar, and water (or a water-containing liquid like milk, cream, egg white, or fruit juice). The way these three components are combined, in what proportions, and at what temperature, determines whether the result is pourable, pipeable, crusting, non-crusting, stiff, silky, matte, or mirror-glossy. Understanding this mechanic is the difference between following a recipe and managing a process.

Think of the structure as a matrix. In a classic American buttercream, the continuous phase is butter fat, with powdered sugar suspended in it. The droplets of water in the butter, and the sugar trapped as a crystalline solid, form a kind of paste that holds its shape when piped. In a royal icing, the continuous phase is water, with sugar dissolved into it and egg white protein providing structure; the water evaporates and the sugar re-crystallizes, giving that rock-hard finish. In a ganache, you have a fat-in-water emulsion that catastrophically inverts if you overheat it.