In stock clarification, the floating layer of impurities is called what?

• A. Foam
• B. Raft
• C. Skim
• D. Scum

Answer: (B)

In stock clarification, the floating layer that forms on top is called the raft. This mass develops when coagulated proteins—often helped by egg whites, along with some mincing of meat, vegetables, and bones—rise and create a network that traps impurities. The raft acts like a natural filter, keeping solids suspended so the liquid beneath becomes clear as it simmers gently. Foam and scum describe surface films of impurities more generally, not the specific floating mass used in the clarification process. Skim is what you do to remove surface impurities, not the name of the layer itself. That’s why raft is the best term for the floating layer during stock clarification.