How to achieve high-quality foam on cappuccino and latte?
In milk for latte and cappuccino, fat content is not important, but the protein content - consistency of foam depends on its:
(a high) protein content, the foam is viscous and oily;
(a small) dry and coarse-grained.
Experienced barista prefers a percentage of protein from 2.8 to 3.8%.
While boiling, proteins’ structure collapses and loses their properties. Therefore, tasty and thick foam is obtained only from raw (pasteurized) milk, of course, not powdered.