There are plenty of lists of numbered food additives, but nature has a code all of its own.

Red - while often a symbol for danger, in foods such as tomatoes, capsicum and strawberries it can show ripeness. In chillies it warns Danger, these are hot!

Green - chlorophyll, vitamin A and calcium, and often C and iron. Darker green means higher nutrition usually. Green on potatoes signals deterioration and danger.

Orange - means vitamins A and C. Brighter orange means better nutrients. 

White - may not always be purest and best. In grains, it means the valuable husk and germ have been stripped away, resulting in less nutrients.

Brown - can be beneficial in the case of grains, showing the germ has been left intact, but brown spots on fruit and vegetables often tells of damage.

Yellow - fruits and vegetables may have vitamins A and C, but yellowing of green vegetables means they are past their prime. Yellow or brown spots on fresh yeast show deterioration.

Black - or dark specks in banana cakes or muffins only show that fibre from the fruit is present. Black seeds in fresh eggplant mean it is older and should be soaked before use to eliminate bitterness.

Purple - red cabbage will turn a violent purple if stewed without some acid such as lemon juice or vinegar.