ABSTRACT
An absolute stability of a colorant does not exist. It always depends on the type and composition of the material to be colored (dyed) and the test conditions. This applies to food, drugs and cosmetics. In lieu of textile fibers (on which most of the common watersoluble colorants have been tested), other substrates are used, e.g., sugar, fruit acids, fats, oils, salts and flavors for food items; functional and auxiliary materials for drugs; active ingredients, emulsifiers, cosmetic agents and perfumes/essences for cosmetic products. Other factors are temperature during manufacture and storage of the finished product. The cotton standard (DIN 54004) cannot be used for the purpose of classification of light stability for food and cosmetic products.
