ABSTRACT
Carotenoids are of widespread occurrence as natural
pigments in plants and animals; they contribute the
natural yellow, orange, and red colors of many plants
as well as being used extensively as nontoxic natural or
nature-identical colorants in foodstuffs (1). Their name
is derived from -carotene, the main representative of their group, which was first isolated from
carrots (Daucus carota) by Wackenroder in 1831 (2).
Carotenoids are isoprenoid polyenes which are formed
by head-to-tail linkage of C5 isoprene units, except for
one tail-to-tail linkage in the center of the molecule,
which makes it symmetrical (3). The C40 carotenoids
can be divided into carotenes, which are hydrocarbons
(e.g., -carotene, Fig. 1a) and their oxygenated derivates, the xanthophylls (e.g., zeaxanthin, Fig. 1b).
Fruit xanthophylls are often acylated with fatty acids
(4). Besides the C40 carotenoids there are also apocar-
otenoids, a degraded form with less than 40 carbon
atoms in the skeleton, and higher carotenoids where
the carbon skeleton contains 45 or 50 carbon atoms,
respectively (5). The characteristic absorption spectrum of each
carotenoid is determined by the chromophore, a
series of conjugated double bounds. Usually the
spectrum shows three absorption bands, which are
affected by the length of the chromophore, the nature
of the double bound and the taking out of conjunction
