Rev. Ruling 55-494
Products, such as Rock and Rye, when packaged with fresh fruit or other like materials may drop somewhat in proof between the time they are bottled and the time they are sold to the consumer purchaser due to the absorption of alcohol by the fresh fruit or other like materials in the bottle. Held, the statement " Proof" may be construed by the consumer as relating to the proof at the time of purchase of the product and therefore would result in deception in those cases where the proof has diminished after bottling. Accordingly, labels on bottles of such products should have the proof shown thereon as "Bottled at Proof," rather than merely as " Proof."
27 U.S.C. 205; 27 CFR 5.36 (27 CFR 5.37)