Reader Mari asks:
Does the process for whipped cream involve casein too? I’ve always thought it was ironic that so many non-dairy cheeses and non-dairy whipped creams contain casein in them, which is what causes an allergic reaction to dairy products for a lot of people. I concluded that casein must have something to do with the structure of cheese and whipped cream. After all, there aren’t any other 38% fat/ 60% water mixtures that can whip up like cream does, right?
Interesting question, Mari! Casein is indeed fascinating stuff, and it abounds in milk (about 5% of milk is casein). You’re absolutely right that it’s critical for things like cheese and yogurt, since it clumps up together when it’s exposed to acid. Those clumps trap fat and water creating the large curds that make cheese, and the tiny curds that make yogurt and sour cream.
But in fact casein doesn’t play a role in whipped cream. The thing that makes cream uniquely whippable among fat-water mixtures is not the amount of fat but the manner in which that fat is delivered: inside those little protein bags that I mentioned, the fat globules. It’s those globules — drawn by the exposed lipids on their surfaces that are created when you agitate the cream — that surround the air bubbles, giving whipped cream its structure. It’s those same globules that give butter its semi-firm texture and prevent it from becoming greasy.
So while casein is unique and vital for many forms of dairying, it isn’t so critical in this case. But that was a wonderful question. Thank you!