How to foam milk for cappuccino?

To foam milk for a cappuccino, you need to incorporate air into warm milk using a steam wand, creating a vortex that homogenises the texture. The target is a microfoam — fine, velvety foam with no visible bubbles — at a temperature of 60 to 65°C. Fresh whole milk is the easiest to work with and gives the best results.

Milk foam for cappuccino (or for any milk coffee) relies on a physical principle: milk proteins (notably casein and whey proteins) denature slightly under heat and trap the air bubbles injected by the steam wand, stabilising the foam. Fat contributes to creaminess and stability. This is why whole milk (3.5% fat) gives better results than skimmed milk — and fresh pasteurised milk works better than UHT milk, whose proteins are already more denatured.

Step-by-step procedure: start with a cold stainless steel jug (straight from the refrigerator), filled to at most one third (milk doubles in volume). Purge the steam wand for 1 second to clear condensation. Plunge the wand just below the milk surface, slightly off-centre. Open the steam fully and lower the jug so the wand stays at the surface — this is the aeration or 'stretching' phase that incorporates air (2–3 seconds maximum, you should hear a sound like crumpling paper). Then push the wand deeper below the surface and maintain the vortex until reaching 60–65°C — the jug should feel hot but not burning to the hand (above 70°C, the foam turns coarse and the milk flavour deteriorates).

Once steam is off, tap the jug on the worktop to burst any large bubbles, then swirl the milk in circles to homogenise the texture. The ideal result looks like glossy paint — smooth, uniform, with satin sheen. For a traditional cappuccino, the foam should be thicker than for a latte: about 1 cm of dry foam at the surface.

Common mistakes: exceeding 70°C (burnt milk, coarse foam), under-aerating (liquid texture with no body), over-aerating (large dry foam with visible bubbles), or failing to swirl after steaming. A surprising fact: the 60–65°C target temperature is not chosen by chance — it is the range where a gentle Maillard reaction of the milk's sugars (lactose) creates new aromatic notes of caramel and hazelnut that perfectly complement the espresso aromas.

Foam types by drink