Rapid Method for Detection and Identification of Synthetic Water-Soluble Coloring Matters in Foods and Drugs

Abstract

A method is described for the rapid detection of coloring matters in foods. In this method, acid dyes from the substrate of foods (starch, pectins, sugars, and gelatin) are dissolved with ammonical alcohol, followed by acidification and adsorption of the dyes from solution onto polyamide powder. Protein-containing foods are treated with acetone to remove fat and water and to coagulate soluble protein. This yields a product which can be used as the filling in a newly designed chromatographic tube; the coloring matters can be eluted with ammoniacal alcohol and the protein remains on the column. Water-soluble forms of natural coloring matters such as chlorophyll, carmine, annatto, alkanna red, betanin, and grape juice red pigment can also be adsorbed on polyamide powder. Basic dyes are adsorbed on carboxymethyl cellulose. Since the coloring matters are eluted at room temperature, they are not expected to undergo irreversible changes during the procedure.