Stability of Natural Colorants in Foods

Many attempts have been made to retain colouration by adding chemicals or modifying processing conditions. Ascorbic acid has been claimed as a stabilizer for natural colourants and conversely, its presence has been cited as the cause of pigment degradation. With anthocyanins, ascorbic acid sometimes has a protective effect, e.g. it absorbs available oxygen and thus prevents oxidation of the anthocyanin. On other hand, enzyme action on ascorbic acid results in the release of hydrogen peroxide, which oxidizes and decolourises the  anthocyanins. Hence, addition  of ascorbic acid to food products will not necessarily stabilize the colour.