A GUIDE TO CAROTENOID ANALYSIS IN FOODS

2 A Guide to Carotenoid Analysis in Foods
bonds), ζ-carotene (7 conjugated double bonds),
neurosporene (9 conjugated double bonds), and
lycopene (11 conjugated double bonds). With the
cyclization of one or both ends of the molecule, the
biosynthetic pathway branches out, forming the
monocyclic β-zeacarotene and γ-carotene and the
bicyclic β-carotene on one side and the monocyclic
α-zeacarotene and δ-carotene and the bicyclic αcarotene
on the other side. α-Carotene may also be
produced through γ-carotene, the β ring being formed
before the ε ring. Hydroxylation leads to the formation
of rubixanthin (monohydroxy) from γ-carotene and
to lycoxanthin (monohydroxy) and lycophyll
(dihydroxy) from lycopene. Introduction of a hydroxyl
group in β-carotene results in β-cryptoxanthin and of
a second hydroxyl group, in zeaxanthin. Similar
modifications of α-carotene produces the
monohydroxy α-cryptoxanthin or zeinoxanthin and the
Table 1. Trivial and semisystematic names of common food carotenoids
Trivial name Semisystematic name
dihydroxy lutein. Epoxidation of β-carotene, βcryptoxanthin,
zeaxanthin, and lutein yields a large
number of epoxy carotenoids.
A semisystematic nomenclature, that conveys
structural information, has been devised for
carotenoids (Table 1), but for the sake of simplicity,
the better known trivial names will be used throughout
this monograph. Also, although the E/Z designation is
now favored to indicate the configuration of the double
bonds, the still widely used cis/trans terminology will
be retained because it is more readily recognized by
workers in the food field. Absolute configuration will
not be dealt with.
Common Food Carotenoids
Of the acyclic carotenes (Figure 2), lycopene and ζcarotene
are the most common. Lycopene is the
Antheraxanthin 5,6-epoxy-5,6-dihydro-β,β-carotene-3,3′-diol
Astaxanthin 3,3′-dihydroxy-β,β-carotene-4,4′-dione
Auroxanthin 5,8,5′,8′-diepoxy-5,8,5′,8′-tetrahydro-β,β-carotene-3,3′-diol
Bixin methyl hydrogen 9′-cis-6,6′-diapocarotene-6,6′-dioate
Canthaxanthin β,β-carotene-4,4′-dione
Capsanthin 3,3′-dihydroxy-β,κ-caroten-6′-one
Capsorubin 3,3′-dihydroxy-κ,κ-carotene-6,6′-dione
α-Carotene β,ε-carotene
β-Carotene β,β-carotene
β-Carotene-5,6-epoxide 5,6-epoxy-5,6-dihydro-β,β-carotene
β-Carotene-5,8-epoxide (mutatochrome) 5,8-epoxy-5,8-dihydro-β,β-carotene
β-Carotene-5,6,5′,6′-diepoxide 5,6,5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β,β-carotene
δ-Carotene ε,ψ-carotene
γ-Carotene β,ψ-carotene
ζ-Carotene 7,8,7′,8′-tetrahydro-ψ,ψ-carotene
Crocetin 8,8′-diapocarotene-8,8′-dioic acid
α-Cryptoxanthin β,ε-caroten-3′-ol
β-Cryptoxanthin β,β-caroten-3-ol
Echinenone β,β-caroten-4-one
Lutein β,ε-carotene-3,3′-diol
Lutein-5,6-epoxide (taraxanthin) 5,6-epoxy-5,6-dihydro-β,ε-carotene-3,3′-diol
Lycopene ψ,ψ-carotene
Neoxanthin 5′,6′-epoxy-6,7-didehydro-5,6,5′,6′-tetrahydro-β,β-carotene-3,5,3′-triol
Neurosporene 7,8-dihydro-ψ,ψ-carotene
Phytoene 7,8,11,12,7′,8′,11′12′-octahydro-ψ,ψ-carotene
Phytofluene 7,8,11,12,7′,8′-hexahydro-ψ,ψ-carotene
Rubixanthin β,ψ-caroten-3-ol
Violaxanthin 5,6,5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β,β-carotene-3,3′-diol
α-Zeacarotene 7′,8′-dihydro-ε,ψ-carotene
β-Zeacarotene 7′,8′-dihydro-β,ψ-carotene
Zeaxanthin β,β-carotene-3,3′-diol
Zeinoxanthin β,ε-carotene-3-ol