Abstract: Spirulina blue, which is not soluble at low pH, is subjected to enzymatic hydrolysis in an aqueous alkaline medium. The pH of the aqueous system is lowered and the liquid phase is dried to produce a blue dye in dry form which is soluble at low pH. The blue dye is useful as a blue colorant in food products, particularly food products, such as beverages, in which acid solubility is desired.

Abstract: This invention relates to a coloring agent which is soluble and stable in low pH aqueous food systems. The food colorant, Food, Drug and Cosmetic Red No. 3, which contains a carboxylic group, is predominantly in the unionized form below pH 4.5 and is, therefore, at a concentration required for red coloring virtually insoluble. Red No. 3 is rendered soluble by mixing it with water and a hydrophilic surfactant selected from the group consisting of polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan tristearate and polyoxyethylene (20) sorbitan monooleate and mixtures thereof. The resulting mixture is added directly to an aqueous foodstuff or after first fixing it on or in a carrier.