Here’s a simple way to clarify a stock: Stir beaten egg whites into simmering broth. Stop stirring and the egg whites will rise to the surface, forming—you guessed it—a raft. As it bubbles, the raft attracts all stray particles.
What does broke the raft mean in cooking?
If you don’t keep the mixture active, it will stick to the bottom on the pot and burn… After it begins to boil, the mixture will float off the bottom of the pot, and you’ll be safe. When the mixture begins to boil, stop stirring, or you’ll break the raft.