Food: The Chemistry of its Components
Chapter 6: Colours
Published:09 Oct 2015
Food colour has of far more than aesthetic importance. Colour is important in the identification of different foods, particularly fruit, and also helps establish ripeness or freshness in most food, including meat (see Chapter 4). Added colours, artificial or natural, can mask the effects of processing etc. and dishonestly mask the true identity of the ingredients of food products. The chemical properties of the natural pigments, chlorophylls (green), carotenoids (yellow, orange, red), anthocyanins (red, purple, blue), betalaines (beet pigments, red) and melanins (particularly in tea), are relevant to food processing and their usefulness as colorants. Other natural food colorants of note are turmeric, cochineal, safflower, sandalwood and malt extract. Colours extracted from microorganisms, e.g. the blue from Spirulina sp. are posing difficult regulatory questions. The number of synthetic dyestuffs (many but not all azo compounds) permitted as food colours has fallen steadily since the 1950s. The possible involvement of some with childhood behavioural disorders has overtaken concern over their potential carcinogenicity. The molecular basis of colour in organic molecules and the measurement of the colour of food materials are topics outside the consideration of particular food substances that concern food chemists. The chapter includes a detailed listing of the synthetic colours permitted in the EU, USA and elsewhere and concludes with a list of specialist books and review articles for further study.