Editorial Note on Part 73
Editorial Note: Nomenclature changes to part 73 appear at 66 FR 66742, Dec. 27, 2001.

§ 73.37 Astaxanthin dimethyldisuccinate. ( a ) *Identity.* ( 1 ) The color additive astaxanthin dimethyldisuccinate is 3,3′-bis(4-methoxy-1,4-dioxobutoxy)-β,β-carotene-4,4′-dione.
( 2 ) Astaxanthin dimethyldisuccinate may be added to the fish feed only as a component of a stabilized mixture. Color additive mixtures for fish feed use made with astaxanthin dimethyldisuccinate may contain only those diluents that are suitable and are listed in this subpart as safe for use in color additive mixtures for coloring foods.
( b ) *Specifications.* Astaxanthin dimethyldisuccinate shall conform to the following specifications and shall be free from impurities other than those named to the extent that such impurities may be avoided by good manufacturing practice: ( 1 ) Physical state, solid.
( 2 ) 0.05 percent solution in chloroform, complete and clear.
( 3 ) Absorption maximum wavelength 484-493 nanometers (in chloroform).
( 4 ) Residue on ignition, not more than 0.1 percent.
( 5 ) Total carotenoids other than astaxanthin dimethyldisuccinate, not more than 4 percent.
( 6 ) Lead, not more than 5 milligrams per kilogram (mg/kg) (5 parts per million).
( 7 ) Arsenic, not more than 2 mg/kg (2 parts per million).
( 8 ) Mercury, not more than 1 mg/kg (1 part per million).
( 9 ) Heavy metals, not more than 10 mg/kg (10 parts per million).
( 10 ) Assay including astaxanthin dimethyldisuccinate, astaxanthin monomethylsuccinate, and astaxanthin, minimum 96 percent.
( c ) *Uses and restrictions.* Astaxanthin dimethyldisuccinate may be safely used in the feed of salmonid fish in accordance with the following prescribed conditions: ( 1 ) The color additive is used to enhance the pink to orange-red color of the flesh of salmonid fish.
( 2 ) The quantity of astaxanthin dimethyldisuccinate in the finished feed, when used alone or in combination with other astaxanthin color additive sources listed in this part 73, shall not exceed 110 milligrams per kilogram (mg/kg), which is equivalent to 80 mg/kg astaxanthin (72 grams per ton).
( d ) *Labeling requirements.* ( 1 ) The labeling of the color additive and any premixes prepared therefrom shall bear expiration dates for the sealed and open container (established through generally accepted stability testing methods), other information required by § 70.25 of this chapter, and adequate directions to prepare a final product complying with the limitations prescribed in paragraph (c) of this section.
( 2 ) The presence of the color additive in finished fish feed prepared according to paragraph (c) of this section shall be declared in accordance with § 501.4 of this chapter.
( 3 ) The presence of the color additive in salmonid fish that have been fed feeds containing astaxanthin dimethyldisuccinate shall be declared in accordance with §§ 101.22(b), (c), and (k)(2), and 101.100(a)(2) of this chapter.
( e ) *Exemption from certification.* Certification of this color additive is not necessary for the protection of the public health, and therefore batches thereof are exempt from the certification requirements of section 721(c) of the act.
[74 FR 57251, Nov. 5, 2009]