Colour and Cooking: Carotenoids

These constitute a large group of yellow, orange, and red pigments found in both plants and animals. The most common carotenoid is B (beta) carotene, which has already been mentioned as the pigment responsible for the colour of normal carrots. It is, incidentally, the constituent of carrots which our bodies break up to produce vitamin A, an aid to night vision.

The carotenoids, like chlorophyll, are insoluble in water. Unlike chlorophyll, they are not affected to any great extent by the presence of an alkali or an acid. The application of heat may speed up the gradual fading which will anyway be induced by exposure to air and by prolonged storage. But it does not produce very noticeable changes. One particular change which occurs is something of an oddity. The carotenoid pigments in swedes turn to a deeper yellow when these vegetables are cooked.