Latte art has a 26-year history, but references to milk mixed with coffee go back more than 300 years.
Milk is approximately 87% water.
The other 13% is mostly made up of sugar (lactose), fat, and protein.
Casein protein helps as an emulsifier.
Whey protein helps stabilise milk foam.
When entraining air, it’s helpful to add the air before the milk gets hot and to increase the volume of the milk by 33%.