Milk Frother
A device that aerates milk to create foam or microfoam for espresso drinks — from handheld wands to automatic machines.
A milk frother is a device that introduces air into milk under heat, creating foam or microfoam for espresso-based drinks such as cappuccino, latte, and flat white. Three main types exist: steam wands (built into espresso machines, producing the highest-quality microfoam), automatic electric frothers (standalone devices that heat and froth simultaneously, such as the Breville Milk Cafe or Nespresso Aeroccino), and handheld battery-powered frothers (small spinning wand devices, low cost, cold or manually heated milk).
Quick facts
- Type
- Equipment
- Gear type
- Milk frother
Steam Wand Technique
An espresso machine steam wand emits pressurised steam that simultaneously heats and aerates milk. The standard technique positions the wand tip just below the milk surface at an off-centre angle to create a rolling vortex. In the first phase (stretching), the tip is kept near the surface to introduce air — the milk volume increases as foam develops. In the second phase (rolling or texturing), the tip goes deeper to heat the milk to 60–65°C without adding more air. The result is microfoam — small, uniform bubbles integrated into the milk rather than large foam sitting on top. Microfoam feels glossy and pourable; latte art requires microfoam. Over-aerated milk (large bubbles) produces a dry, unsatisfying texture.
Automatic Electric Frothers
Automatic frothers (such as the Nespresso Aeroccino, Jura hot milk system, and Breville Milk Cafe) use an induction heating base and a motorised whisk to simultaneously heat and froth milk in one chamber. They are simple to operate: add cold milk to the fill line, press a button, and receive heated frothy milk in 60–90 seconds. The foam quality is acceptable for home cappuccino and latte but lacks the microfoam density and glossiness achievable with a steam wand. Automatic frothers can produce both hot foam (for cappuccino) and cold foam (for cold drinks) depending on the model.
Milk Fat and Protein in Frothing
Milk froths because of its protein content (casein and whey proteins) — proteins stabilise the air bubbles. Fat content affects foam texture: whole milk (3.5% fat) produces the richest, most stable microfoam; low-fat milk produces more volume but less stable foam; skim milk produces the highest volume foam but with a thinner texture. Temperature is critical: milk proteins denature above 70°C, collapsing foam structure and producing a scalded, flat flavour. The ideal steaming temperature of 60–65°C is the balance point where proteins are sufficiently denatured for stability without collapsing. Plant milks vary — barista oat milk and barista soy milk are formulated with higher fat and protein specifically for frothing.
Sources & further reading (2)
- encyclopedia — accessed 2026-05-06
- industry-standard — accessed 2026-05-06
Frequently asked questions
What is the difference between foam and microfoam?
Foam consists of relatively large air bubbles visible in the milk, producing a fluffy, dry texture that sits on top of the drink (as in a traditional cappuccino). Microfoam consists of extremely small, uniformly distributed air bubbles that are fully integrated into the milk, producing a glossy, liquid-like texture that pours and can be used for latte art. Microfoam is produced by a properly operated steam wand; foam is produced by over-aeration or by electric frothers. Specialty coffee standards prefer microfoam for lattes and flat whites.
Can plant milks be frothed?
Yes, but with variable results. Standard supermarket oat, almond, and soy milks froth poorly due to low protein and fat content. Barista editions of oat milk (Oatly Barista, Minor Figures), soy milk, and almond milk add protein and fat specifically for steaming performance. Oat milk barista editions produce the best microfoam of the plant milk alternatives. Coconut milk froths poorly and separates under heat. Macadamia and pea protein milks vary by brand.
What temperature should frothed milk reach?
The target temperature for steamed and frothed milk in espresso drinks is 60–65°C (140–150°F). At this temperature, milk sugars dissolve and produce perceived sweetness; proteins are denatured enough to stabilise foam. Below 55°C, the milk may taste thin and underheated. Above 70°C, proteins over-denature and the milk develops a scorched, flat taste. A milk thermometer or heat-sensing pitcher is used to stop steaming at the correct temperature.