2009_Book_FoodChemistry

3.8 Unsaponifiable Constituents 235
Fig. 3.46. Tocopherol and tocotrienol analysis by HPLC (according to Cavins and Inglett, 1974). 1 α-Tocopherol,
2 α-tocotrienol, 3 β-tocopherol, 4 γ-tocopherol, 5 β-tocotrienol, 6 γ-tocotrienol, 7 δ-tocopherol, and 8 δ-tocotrienol
They provide the intensive yellow, orange or red
color of a great number of foods of plant origin
(Table 3.55; cf. also 17.1.2.3 and 18.1.2.3.2).
They are synthesized only by plants (see a textbook
of biochemistry). However, they reach animal
tissues via the feed (pasture, fodder) and can
be modified and deposited there.
A well known example is the chicken egg yolk,
which is colored by carotenoids. The carotenoids
3.8.4.1 Chemical Structure, Occurrence
Other carotenoids are derived by hydrogenation,
dehydrogenation and/or cyclization of
the basic structure of the C 40 -carotenoids
(cf. Formula 3.117). The cyclization reaction can
occur at one or both end groups. The differences
in C 9 -end groups are denoted by Greek letters
(cf. Formula 3.118).
(3.117)
in green plants are masked by chlorophyll. When
the latter is degraded, the presence of carotenoids
is readily revealed (e. g. the green pepper becomes
red after ripening).
A semisystematic nomenclature used at times
has two Greek letters as a prefix for the
generic
Table 3.55. Carotenoids in various food
Food Concen- Food Concentration
tration
(ppm) a
(ppm) a
Carrots 54 Peaches 27
Spinach 26–76 Apples 0.9–5.4
Tomatoes 51 Peas 3–7
Apricots 35 Lemons 2–3
a On dry weight basis.
(3.118)