1. Introduction
Colour is a main feature of foods. Its affect on people is not only
visual; it is also associated with food variety, quality, and freshness.
Food colourants have been used to replace natural food colour,
which can be lost during preparation processes. Colourants
are also used to prevent colour changes in the final product
(Berzas, Flores, Llerena, & Farinas, 1999) and provide attractiveness
to consumers, particularly children (Hofer & Jenewein, 1997). In
recent years, natural food colourants isolated from suitable plants,
fungi, or insects have been increasingly used. However, many
natural colourants become unstable under processing conditions
such as, light, oxygen, and pH. Natural colourants are also more
expensive than synthetic ones. The use of synthetic organic dyes
has been recognised as the most reliable and economical method
of restoring or providing colour to a processed product. However,
some of these substances pose potential risks to human health,
especially when consumed in excess.
To prevent indiscriminate use, laws and regulations based in
toxicological studies on experimental animals and human clinical