Functional properties of carotenoids

The importance of carotenoids for colouration in living organisms has already been mentioned. For example, apart from their universal occurrence in the photosynthetic apparatus of phototrophic bacteria, carotenoids are also often 

Various natural pigments, including carotenoids, are widely used as additives to provide an attractive colour to manufactured foods (Nir et al., 1993 Antony and Shankaranarayana, 2001 Baker, 2001). Natural extracts have been used for this purpose for centuries, especially annatto, saffron, tomato, paprika and red palm oil. In the food industry, carotenoids are prepared in oily or aqueous mecha, including emulsions, colloidal suspensions, and complexes with proteins (Klaui, 1979). These preparations find widespread applications in margarine, butter, fmit juices and beverages, canned soups, dairy products, desserts and mixes, preserves and symps, sugar and flour confectionery, salad dressings, meat, pasta, and egg products. Carotenoids are also widely used as additives in animal feeds to impart the desired colour to animal tissues or to derived products, or to provide adequate vitamin supplies. 

Carotenoids can also react with free radicals and thus act as chain-breaking antioxidants, although they do not have the specific characteristic stmctural 

The relative antioxidant activities of carotenoids in multilamellar liposomes, as assayed by inhibition of the formation of thiobarbituric acid-reactive substances (TBARs), were lycopene a-carotene p-cryptoxanthin zeaxanthin= P-carotene lutein (Stahl et al, 1998). Mixtures of carotenoids were more effective than the single compounds, and this synergistic effect was most pronounced when lycopene or lutein was present. The superior antioxidant activity of mixtures of carotenoids may be related to the specific positioning of different carotenoids within cell membranes. 

These contradictory results, showing evidence of both antioxidant and prooxidant activity, may suggest that the antioxidant behaviour of carotenoids is closely related to their own oxidation. Studies of the kinetics of carotenoid oxidative degradation under different conditions, as well as of the sttuctures of the products formed, have allowed the mechanism of the oxidation process to be clarified (Yanishilieva et al, 1998). 

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Perera CO and Yen GM. 2007. Functional properties of carotenoids in human health. Int J Food Prop 10 201-230. 

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