"Little Miss Muffet, sat on her tuffet, eating her curds and whey. Alon..." You may remember this beloved nursery rhyme, but have you ever wondered, 'what are curds and whey?"

Cottage Cheese

Actually, you've probably eaten curds and whey without knowing it. Curds and whey are actually the lumps and liquid found in cottage cheese.

If you didn't know, cottage cheese is made from skim milk. But how exactly does skim milk become curds and whey?

The Complexities Of Milk

In spite of its simple appearance, skim milk is chemically quite complex. There are dozens of different proteins floating around in that white fluid.

Fortunately, for cottage cheese makers, all the proteins in milk can be separated into two basic groups by simply adding a chemical called rennin. Rennin is an enzyme from a calf's stomach, and it makes some of the proteins in milk clump together.

These clumping proteins are called "curd proteins," while the milk proteins that refuse to clump are called "whey proteins." These proteins are the curds and whey of Miss Muffet's lunch.

Voilà

Unfortunately, whey doesn't actually taste very good--so modern cottage cheese makers tend to press or wash their product, leaving a cottage cheese that is mostly curds.

But that's how you get curds and whey. They are two kinds of milk proteins, which separate when you add rennin to them.