Food Chemistry

244 3 Lipids

(3.143)

3.8.4.5 UseofCarotenoidsinFoodProcessing

Carotenoids are utilized as food pigments to color
margarine, ice creams, various cheese products,
beverages, sauces, meat, and confectionery and
bakery products. Plant extracts and/or individual
compounds are used.

3.8.4.5.1 PlantExtracts...........................................

Annato is a yellow oil or aqueous alkaline
extract of fruit pulp ofRakuorOrleansshrubs or
brushwood (Bixa orellana). The major pigments
of annato are bixin (XVIII) and norbixin, both of
which give dicarboxylic acids upon hydrolysis.
Oleoresin from paprika is a red, oil extract
containing about 50 different pigments. The
aqueous extract of saffron (more accurately,
from the pistils of the flowerCrocus sativus)
contains crocin (XVII) as its main constituent.
It is used for coloring beverages and bakery
products.
Raw, unrefined palm oil contains 0.05–0.2%
carotenoids withα-andβ-carotenes, in a ratio
of 2:3, as the main constituents. It is of particular
use as a colorant for margarine.

3.8.4.5.2 Individual Compounds

β-Carotene (VII), canthaxanthin (XII), β-
apo-8′-carotenal (XIX) and the carboxylic
acid ethyl ester derived from the latter are
synthesized for use as colorants for ed-
ible fats and oils. These carotenoids, in
combination with surface-active agents, are
available as micro-emulsions (cf. 8.15.1) for

coloring foods with a high moisture con-

tent.

3.8.4.6 Analysis...............................................

The total lipids are first extracted from food

with ispropanol/petroleum ether (3:1 v/v) or

with acetone. Alkaline hydrolysis follows,

removing the extracted acyl-lipids and the

carotenoids from the unsaponifiable fraction.

This is the usual procedure when alkali-

stable carotenoids are analyzed. Although

carotenoids are generally alkali stable, there

are exceptions. When alkali-labile carotenoids

are present, the acyl lipids are removed

instead by a saponification method using

column chromatography as the separation

technique.

A preliminary separation of the lipids into classes

of carotenoids is carried out when a complex

mixture of carotenoids is present. For example,

column chromatography is used with Al 2 O 3 as

an adsorbent (Table 3.60). Additional separation

into classes or individual compounds is achieved

Table 3.60.Separation of carotenoids into classes by

column chromatography using neutral aluminum oxide

(6% moisture) as an adsorbent P: Petroleum ether,

D: diethyl ether

Elution with Carotenoids in effluent

100% P Carotenes

5% D in P Carotene-epoxides

20–59% D in P Monohydroxy-carotenoids

100% D Dihydroxy-carotenoids

5% Ethanol in D Dihydroxy-epoxy-carotenoids