Food Additives

Natural Colours

These are obtained from natural sources such as grasses, leafy vegetables, fruit skins, roots and seeds of plants.

Animals can also be a source of food colourings. Cochineal, or carminic acid, is a red colour that is obtained from the bodies of certain scale insects. These feed off cactus leaves and their bodies are commercially harvested in Africa, Spain and Central America. Their bodies are dried and crushed to extract the red colouring.

Click on the picture to see the chemical formula for carminic acid.

Dried bodies of cochineal insects.
Picture: Florida Center for Instructional Technology, University of Florida

Nature Indentical Colours

Obtaining colours from natural sources can be costly and their quality can vary. To overcome this, chemists have found ways to make identical colours in the laboratory. This improves their purity and may also cost less.

Nature identical colours are exactly the same molecules found in natural sources but they are made synthetically.

The main chemical classes are:

• flavonoids, found in many flowers, fruits and vegetables
  
• indigoid, found in beetroot
  
• carotenoids, found in carrots, tomatoes, oranges and most plants.
  Carrots contain an orange molecule called beta-carotene which is part of this group.

Most natural and nature identical colours can dissolve in oil but do not dissolve in water. This means it is difficult to add them directly to foods. They are usually processed to form their sodium or potassium salt. This makes them soluble in water and suitable for use in foods. They may also be dissolved in oil and incorporated into water-soluble beadlets.

Carrots contain orange-coloured molecules called carotenoids.
An example of a carotenoid is beta-carotene.
Photo: USDA.

Click on the picture to see the chemical structure of beta-carotene.

Synthetic Colours

These are colours that do not occur in nature and have been made in a factory. They have been carefully tested to make sure that they are safe. The main examples of synthetic colours are:

• azo dyes, such as amaranth (colour for blackurrant jams).
  
• 'other' dyes, such as, quinoline, (quinoline yellow), xanthene, (erythrosine), triarylmethanes, indigoid, (indigo carmine).

Synthetic colours are usually water soluble and can be used in foods without any further processing.

'Aramnth' (E123) is a synthetic food colouring