27 CFR §18.52

1. (a)General. High-proof concentrate may be produced in a concentrate plant. Concentrate having an alcohol content of more than 24 percent by volume that is fit for beverage use may not be produced in a concentrate plant.
2. (b)Determination. A proprietor shall determine whether a particular concentrate is a high-proof concentrate. However, a proprietor may at any time submit a written request to the appropriate TTB officer for a determination of whether a concentrate is unfit for beverage use. Each request for a determination will include information as to kind, percent alcohol by volume, and fold of the concentrate. The request will be accompanied by a representative 8-ounce sample of the concentrate.