Plant sources
Although there is a multitude of colours in the plant kingdom, their extraction and use in food systems is not an easy task. Unless the colourants have some outstanding advantage, e.g. good stability in food or very high tinctorial power, it is generally not worth continuing. Assuming that the source provides a colourant with exceptional properties, further considerations need to be taken into account. A major problem with the plant sources is their availability, as most plants are seasonal. Many of the plant sources listed in literature would require major planting programmes to provide sufficient material for production purposes. Another consideration is the cost of extraction and processing, which is obviously minimal for an aqueous extraction, but will be greater, if organic solvents are used and subsequently recovered.