The science of frothing milk: • Proteins and fats in milk are responsible for how well the milk with be frothed. The act of steaming milk is essentially forcing air into the milk while increasing the milk's temperature. The protein in the milk is what stabilizes the entrapped air and forms bubbles and froth.

How is milk foam made?

When we foam milk, we are forcing water vapour and air into milk while heating it. The proteins create spheres around the air and stabilise into bubbles. The protein chains in milk are polar: one end is hydrophilic (attracted to water), and the other is hydrophobic (repelled by water).

Which milk is best for frothing?