Simultaneous analysis of carotenoid colorings in foods by thin layer chromatography

We established a simultaneous analysis method by TLC for carotenoid colorings (annatto extract, orange color, gardenia yellow, paprika color, tomato color, marigold color, and beta-carotene) in foods. Reversed phase C-18 TLC using the solvent systems of acetonitrile-acetone-n-hexane (11 : 7 : 2) and acetone-water (9 : 1), and normal phase silica gel TLC, using the solvent systems of n-hexane-diethyl ether-acetic acid (4 : 1 : 1) and benzene-ethyl acetate-methanol (15 : 4 : 1) yielded well-delineated spots with good separation. These TLCs were applied to the analysis of a total of 294 commercially available foods, and the Rf value of each color spot was evaluated under the four TLC conditions. The difference in the Rf value was slight between each color extracted from the food samples and the standard color, and the coefficient of variation was small, indicating excellent reproducibility. The present method is considered to be useful for the rapid analysis of the carotenoid colorings.