Natural Pigments in Foods

Chromaphoric compounds are substance that contain chroma. There are functional groups called chromaphores which when added to a saturated hydrocarbon, causes absorption in the UV or visible range, to produce colors. Saturated hydrocarbons are colorless, but when a chromaphore is added to it, a color compound is produced.
E.g. of simple chromaphores include the following:

1. Carbonyl Group
This is a carbon atom bonded to an oxygen atom like in Aldehydes and Ketones.

2. Azo Group
This is a Nitrogen atom bonded to another Nitrogen atom. It absorbs light in the visible UV region. Most synthetic food colors are in the form of azo-dyes. E.g. of an compound with an azo group is Azo Benzene.

3. Nitrate Group
This is a Nitrogen atom bonded between two Oxygen atoms. This chromaphore also absorbs light in the visible UV region.

4. Ethylene Group
This isolated chromaphoric group absorbs light at a wavelength of 190nm. It consists of two double-bonded carbon atoms. The amount of light absorbed by this chromaphoric group as part of a complex compound varies, depending on its molar absorptivity. When a compound contains conjugated ethylene groups, the wavelength for light absorption increases.

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