Whole milk. Choose milk with a protein content and fat content preferably both above 3%.

Milk has three main components: protein, carbohydrates, and fat. Protein is roughly 3 to 4 percent of milk, and skimmed and semi-skimmed milk have a higher ratio of protein content than carbohydrates and fat. Protein can be broken down into two main substances: milk protein and whey.

The different protein content of different milks affects the ability of different milks to maintain a milk froth, and therefore the barista's ability to garnish a latte. Whole milk will deliver a thick, heavy layer of milk foam, while skim milk will deliver more froth and larger bubbles.

Expanded:

Notes:

1. The amount of air pressure in the steam lever . (The size of the steam rod air pressure will make the milk froth form different degrees of tumbling during the whipping process, the higher the air pressure, the higher the integration.)

2. The fineness of the milk froth. (The more delicate the milk froth, the less air contained in a single milk froth, high density, small buoyancy; the more rough the milk froth, the more air contained in a single milk froth, low density, large buoyancy. If the milk froth is more rough, the milk froth will quickly float on the surface of the milk, the integration is low; if the milk froth is more delicate, the milk froth will float on the surface of the milk at a slow speed, the integration is high).

3, heat the milk to about 60 degrees, but not more than 70 degrees, otherwise the protein structure in the milk will be destroyed.

Baidu Encyclopedia - Milk Foam

Baidu Encyclopedia - Whole Milk