Coffee Knowledge Base

20 February 2024

Crafting the perfect cappuccino: a guide to silky milk froth

Crafting the perfect cappuccino: a guide to silky milk froth

There is no better way to pamper your guests or to win customer loyalty than by giving them a perfectly made cappuccino. But how do you make that perfect silky milk topping? Nice milk froth (or foam) should be thick, silky, creamy and sweet. Air bubbles, excessively warm milk, or froth that is too dry should be avoided.

The science behind milk

Milk contains fats, proteins and sugars. Whey is one of the proteins and that is the magic factor that creates the nice, thick, creamy effect with steamed milk. Steaming the milk makes the proteins in the milk bind, creating a solid, creamy mass. It is important to know that the binding occurs at its best up to about 40 °C.

To make milk froth airy, you add air to it from under the surface, which creates the foam by stretching it and drawing it out. This has to be done at a temperature no higher than 40 °C. If you continue the process after reaching that temperature, the milk will produce a hard and dry foam that is difficult to mix with the espresso. This is why you should preferably start the process with a cold frothing jug and cold milk so that you have more time before you reach 40 °C. Of course, 40 °C is not a pleasant drinking temperature for a hot drink.

The milk you actually add to the coffee must be hotter. However, if the milk is hotter than 70 to 75 °C, the creamy froth you have created will become sloppy and unstable again. The milk will burn at temperatures above 75 °C, and you will smell that. At that stage it has lost the sweet and creamy effect.

Steaming milk step by step

  • Start with cold milk from the refrigerator and a cold jug.
  • Preferably use pasteurized, fresh milk, and not UHT.
  • Fill the frothing jug, but no more than half-full.
  • Prepare the espresso so that the milk and coffee are ready at the same time.
  • Blow some steam onto the drip tray and wipe the steam pipe clean with a damp cloth.
  • Hold the milk jug parallel to the work surface, and make sure that the steam nozzle is covered with milk. •Turn the jug fifteen degrees to the left or right to create an angle in the jug – the steam pipe is not in the centre now.
  • Open the steam valve fully.
  • Ensure stability by resting the pipe of the steam nozzle in the spout of the jug.
  • Gently lower the frothing jug to add air under the milk and to stretch it.
  • The steam pipe is now hovering around the surface of the milk and, if all is going well, you hear a nice hissing sound.
  • The air coming out of the steam pipe blows against the wall of the milk jug and thereby creates a nicely controlled vortex.
  • Hold the jug still. All movements must always be steady and controlled.
  • Hold the jug with one hand so that the other is free for checking the temperature next to the side of the jug.
  • Once you reach a temperature of 40 °C, almost no more air is added but the milk continues to gain texture.
  • Keep your hand against the jug to feel the temperature. As soon as the jug becomes too hot to bear comfortably, you have reached the limit of about 70 °C and you turn off the steam. During your early days, you should use a thermometer to check the temperature. You will eventually learn to feel this instinctively with the palm of your hand.
  • Put the frothing jug back in its place and clean the steam pipe with a damp cloth. Blow some steam through the pipe so that there is definitely no milk residue remaining on the spout.
  • Tapping the jug on a hard surface for a while will burst any air bubbles. If your steaming technique is perfect, this step is unnecessary.
  • Now roll the milk in the jug with a smooth motion so that you polish the milk. You will see that the milk has a beautiful shine on the surface.
  • If you steam hotter than 75 °C, what we know as the ‘microfoam’ loses its firmness. Both the sweet flavour and the desired texture are then lost. And your customer will burn his or her tongue – and that is definitely not the intention. So keep a good eye on the temperature every time.
  • However, the most common mistake is steaming lukewarm. So don’t just assume that you have the temperature perfectly under control; check it regularly with a thermometer.
  • Remember that the proteins break down completely from 75 °C upwards.
  • And last but not least – enjoy your cappuccino!