I've been seeing if you can drain it down to say, 1 to 3% and document your break in lots you're doing pretty well. If you can drain it to zero, clean, and document, obviously that is perfect world. Doing either may be costly depending upon how readily able you are to do so.
Primarily, though, your operation should do a risk analysis on this ingredient, history of recalls, etc. You should also do risk analysis of *cleaning* the tank as well. In a previous operation, we found through risk analysis that it was better if we do not clean them, but inspect first, clean if necessary.