21 C.F.R. § 73.170
(a) Identity.
(b) Specifications. Grape skin extract (enocianina) shall conform to the following specifications:
Pesticide residues, not more than permitted in or on grapes by regulations promulgated under section 408 of the Federal Food, Drug, and Cosmetic Act. Lead (as Pb), not more than 10 parts per million. Arsenic (as As), not more than 1 part per million.
(c) Uses and restrictions. Grape skin extract (enocianina) may be safely used for the coloring of still and carbonated drinks and ades, beverage bases, and alcoholic beverages subject to the following restrictions: