How do you know when brie you s too old to use?

You can tell brie is too old to use by checking for off smells, unusual discoloration, or a slimy texture. If the cheese has developed a strong ammonia scent or has visible mold that isn't part of its natural rind, it's best to discard it. Additionally, if it tastes sour or has a grainy texture, it's a sign that the brie has gone bad. Always trust your senses; when in doubt, throw it out.