Global Coffee Day- Texture and Temperature
30 October 2020 by Matt Lawrence
Texture
The ideal texture for foamed and steamed milk is velvety smooth. The surface of the milk looks quite shiny or glassy. The bubbles are very, very small — the smaller the better. There are no large bubbles. Perfect foam with very small bubbles is often called ‘Microfoam’ In contrast, poor form with large bubbles is described by some baristas as ‘sea foam’
Generally after successful foaming and steaming milk you will have doubled the volume in the jug. If you start with a jug one third full of milk, you would generally finish with a jug two thirds full of foamed and steamed milk. The volume has increased because air has been added. During the process of foaming, air bubbles are sucked into the milk and bind around the whey proteins of the milk. This is how milk foam is created.
The position of the steam wand is critical to achieving good texture. If the steam wand is not in the correct position in the milk and at the right angle to the jug, you will never be able to make sufficient foam. Nor will you be able to produce good quality foam.
The correct position for the end of the steam wand is just under the surface of the milk. It is also generally between the centre and the side of the jug. On most machines you should be able to see part of the steam nozzle while you are foaming and steaming. In this position the milk sucks in the maximum amount of air as it whirlpools around the wand.
The angle of the steam wand varies according to the technique of the barista. Some prefer the steam wand to be parallel to the side of the jug, Others find it necessary to change the angle according to how and where the milk is moving in the jug.
You will know because
- You see a whirlpool moving around the steam wand.
- you hear a soft hissing sound as the milk takes air in through the holes in the steam nozzle.
A hollow, gurgling sound is an indication the steam wand is too far out of the milk.
Once the whirlpool and the soft hissing sounds are evident, you need to hold the jug steadily in this general position.
Temperature
The ideal temperature for foamed and steamed milk is approximately 68%. The Milk should also be heated evenly throughout the jug. The temperature gives the best flavour to the resulting beverage and also allows the customer to drink it straight away without buring their mouth.
When milk is heated beyond about 72% the protein in the milk undergoes a considerable and irreversible change and it will not foam as well. At a temperature higher than 68%, it is difficult to perfect foam. If the milk boils or even approaches, it also tastes burnt rather than sweet.
Assessing the Milk
- Sight- Look at the milk as it is moving in the jug- Look for the whirlpool, Steam wand position
- Sound- Listen to the sound the steam makes as it is passing through the milk
- touch- Feel the sides, Consider sensory and how hot the jug should be. Use a Temperature Gauge/Sticker
- time- Concentrate on how long the foaming and steaming process is taking.
These four signs will enable you to monitor the texture and temperature of the milk together and, with experience will be your guaranteed success.
