By clarifying butter, e.g. by melting butter and filtering it, we rid ourselves of most of the protein in the butter, and are left with mostly fat. However, the separation of protein and fat is not complete. Some people cannot eat milk proteins due to allergic reactions, and cannot therefore use unrefined butter in their cooking.
Is there a simple "home-kitchen" procedure to test whether the filtration sufficiently removed the milk proteins? Any proteins in the ghee can be precipitated by adding acetic acid, but this is not specific to milk proteins.
Does anyone have any ideas?