Natural hydrophilic carotenoids

The nature of the medium, hydrophilic or lipophilic, in which the antioxidant is to be effective is a further important question, which has been tackled with respect to human plasma by Yeum et al.465 They used ABAP as a hydrophilic radical generator and 2,2 -azobis(4-methoxy-2,4-dimethylvaleronitrile) as a lipophilic radical generator. In the former case, the rates of consumption of antioxidants decreased in the order, ascorbic acid > a-tocopherol > uric acid > lycopene > lutein > cryptoxan-thin > /1-carotene, whereas, in the latter case, a-tocopherol and carotenoids were depleted at similar rates, ahead of ascorbic and uric acid. The behaviour of melanoidins of different types under such conditions would be of interest. 

The matrix solution contains a protective colloid, usually gelatin, which is adsorbed in a thin layer on the surface of the carotenoid particles which are thus made hydrophilic and can form stable dispersions in water at suitable pH. Depending on the nature of the further processing, the matrix solution also contains additives, for example natural antioxidants such as tocopherol and ascorbic acid, emulsifiers such as lecithin and ascorbyl palmitate, and sugar and starch to improve the mechanical properties of the end products. 

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