CANTHAXANTHIN-斑蝥黄质

CANTHAXANTHIN Prepared at the 51st JECFA (1998), published in FNP 52 Add 6 (1998) superseding specifications prepared at the 44th JECFA (1995), published in FNP 52 Add 3 (1995). ADI 0-0.03 mg/kg bw, established at the 44th JECFA in 1995. SYNONYMS CI Food Orange 8; INS No. 161 g; CI (1975) No 40850 DEFINITION Consists predominantly of trans-ß-carotene-4,4'-dione together with minor amounts of other isomers; diluted and stabilized forms are prepared from canthaxanthin meeting these specifications and include solutions or suspensions of canthaxanthin in edible fats or oils, emulsions and water dispersible powders; these preparations may have different cis/trans isomer ratios; the analytical methods described for the parent colour are not necessarily suitable for the assay of or determination of impurities in the stabilized forms (appropriate methods should be available from the manufacturer). These specifications define only synthetic canthaxanthin and do not cover any commercially available food colour from natural sources. Chemical names ß-Carotene-4,4'-dione; canthaxanthin; 4,4'-dioxo-ß-carotene C.A.S. number 514-78-3 Chemical formula C40H52O2 Structural formula Formula weight 564.86 Assay Not less than 96% of total colouring matters (expressed as canthaxanthin) DESCRIPTION Deep violet crystals or crystalline powder; sensitive to oxygen and light and should therefore be kept in a light-resistant container under inert gas FUNCTIONAL USES Colour CHARACTERISTICS IDENTIFICATION Solubility (Vol. 4) Insoluble in water, insoluble in ethanol, practically insoluble in vegetable oils, very slightly soluble in acetone Spectrophotometry (Vol. 4) A solution in cyclohexane has an absorbance maximum between 468 and 472 nm Positive test for carotenoids The colour of a solution of canthaxanthin in acetone disappears after successive additions of a 5 % solution of sodium nitrite and 1 N sulfuric acid PURITY Sulfated ash (Vol. 4) Not more than 0.1% Test 2 g of the sample (Method I) Subsidiary colouring matters Carotenoids other than canthaxanthin: not more than 5% of total colouring matters See description under TESTS Lead (Vol. 4) Not more than 2 mg/kg Determine using an atomic absorption technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on the principles of the methods described in FNP 5, “Instrumental Methods”. TESTS PURITY TESTS Subsidiary colouring matters Dissolve about 80 mg of sample in 100 ml chloroform. Apply 400 µl of this solution as a streak 2 cm from the bottom of a TLC-plate (Silicagel 0.25 mm). Immediately develop the chromatogram with a solvent mixture of 95 parts dichloromethane and 5 parts diethyl ether in a saturated chamber, suitably protected from light, until the solvent front has moved 15 cm above the initial streak. Remove the plate, allow the main part of the solvent to evaporate at room temperature and mark the principal band as well as the bands corresponding to other carotenoids. Remove the silicagel adsorbent that contains the principal band, transfer it to a glass-stoppered 100 ml centrifuge tube and add 40.0 ml chloroform (solution 1). Remove the silicagel adsorbent that contains the combined bands corresponding to the other carotenoids, transfer it to a glass-stoppered, 50 ml centrifuge tube and add 20.0 ml chloroform (solution 2). Shake the centrifuge tubes by mechanical means for 10 min and centrifuge for 5 min. Dilute 10.0 ml of Solution 1 to 50.0 ml with chloroform (solution 3). Determine, with a suitable spectrophotometer, the absorbances of Solutions 2 and 3 in 1-cm cells at the wavelength maximum about 485 nm, using chloroform as blank. Calculation Carotenoids other than canthaxantin (%) = where A2 = absorbance of Solution 2 A3 = absorbance of Solution 3 METHOD OF ASSAY Proceed as directed under Total Content by Spectrophotometry (see Volume 4) using the following conditions: W = 0.1 g V1 = V2 = V3 = 100 ml v1 = v2 = 5 ml A1%1 cm = 2200 wavelength max = about 470 nm CANTHAXANTHIN SYNONYMS DEFINITION Chemical names C.A.S. number Chemical formula Structural formula Formula weight Assay DESCRIPTION FUNCTIONAL USES CHARACTERISTICS IDENTIFICATION Spectrophotometry Positive test for carotenoids PURITY Subsidiary colouring matters Lead (Vol. 4) TESTS PURITY TESTS Subsidiary colouring matters METHOD OF ASSAY