Skim Milk foamers

[Robin Shuster]

I have been trying to figure out why it is that the skim milk foamers (they look like small, skinny French Press Coffee makers) create good foam with skim milk, but not with whole milk. The instructions call for warmed (but not boiled) skimmed milk. What role does the moderate heat and the lack of milk fats play in the greater foam volume?

Many thanks for your new edition. I have been waiting for it for years with great eagerness.

Robin

[Harold McGee]

Thanks--I hope you enjoy the new edition. Milk foams are stabilized by the whey proteins, and skim milk is usually fortified with added whey proteins to provide the body removed when the fat is removed. The whey proteins are most efficient foam stabilizers when they're unfolded--denatured--by moderate heat, and become less so when boiled--they bond to each other and to the casein proteins and so aren't available for reinforcing the bubble walls.