To the tetrahedral terpenes counting group of dyes with over 800 naturally occurring, different types. They are widespread in the animal and plant kingdom and cause a yellow, green, orange to reddish color. The carotenoids are in the photosynthesis responsible for protection against photo-oxidation, as well as for energy transfer. The most common carotenoids are β-carotene (carrot), a precursor of Vitamin A and lutein. Lutein-5,6-epoxide, luteoxanthine, neoxanthine, violaxanthine, xanthophylls and zeaxanthine are found in lower concentrations. Carotenoids are also used for coloring and as a flavor enhancer for food. Some carotenoids act as antioxidants and therefore have a preventive effect in many diseases such as Alzheimer's, arteriosclerosis, cataracts, skin aging, cancer, Parkinson's and rheumatism.
Compared to other fruits, grapes have low carotenoid levels. The carotenoids are an important precursor to norisoprenoids which in white and red grape varieties play an important role for the Aroma - Play expression. They are caused by chemical processes such as enzymatic oxidation at the end of ripening, at fermentation and formed during ripening. These include Damascenone (β-Damascenon) and that for the petrol tone responsible TDN (Trimethyl-Dihydronaphtalin). The second group of plant dyes found in grapes are flavonoids who are mainly responsible for the dark colors from blue to black.