Page 40 - Academic Press Encyclopedia of Physical Science and Technology 3rd BioChemistry

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Encyclopedia of Physical Science and Technology EN006C-254 June 28, 2001 19:52

112 Food Colors

tribution in foodstuffs, while flavonone glycosides are of
special interest in citrus fruits.
Catechins, or flavan-3-ols, are present mainly in woody
tissues. Among common foods, tea leaves contain at least
six catechins representing about 25% of the dry weight
of tea leaves. Tea catechins are excellent substrates for
the catechol oxidase that is present in tea leaves and par-
ticipates in the conversion of green tea to black tea. The
reddish brown color of tea brew is due to a mixture of

FIGURE 7 Stacked molecular complex of awobanin and flavo-
commelin; p-C. denotes p-coumaroyl. [From Osawa, Y. (1982). TABLE III Anthocyanidins Present as Anthocyanins in Fruits
In “Anthocyanins as Food Colors” (P. Markakis, ed.), Academic and Vegetables
Press, New York.]
Fruit or vegetable Anthocyanidin
Exposure to high temperatures and contact with the oxy- Apple (Malus pumila) Cyanidin
gen of the air appear to be two factors affecting antho- Blackberry (Rubus fructicosus) Cyanidin
cyanin stability most adversely. Ascorbic acid accelerates Black currant (Ribes nigrum) Cyanidin. delphinidin
the destruction of anthocyanins, and so does light. Cer- Blueberry (lowbush,Vaccinium Delphinidin, petunidin,
tain oxidizing enzymes, such as phenol oxidase, and a angustifolium; highbush, malvidin, peonidin,
V. corymbosum) cyanidin
hydrolyzing enzyme known as anthocyanase may con-
Cherry (sour, ‘Montmorency,’ Prunus Cyanidin, peonidin
tribute to the degradation of anthocyanin pigments. Ox-
cerasus; sweet, ‘Bing,’ P. avium)
idizing enzymes act on the anthocyanidin moiety, while
Cranberry (Vacinnium macrocarpon) Cyanidin, peonidin
anthocyanase splits off the sugar residue(s); the freed an-
Elderberry (Sambucus nigra) Cyanidin
thocyanidin is very unstable and loses its color sponta-
Fig (Ficus carica) Cyanidin
neously. Sulfur dioxide, which is used for the preser-
Gooseberry (Ribes grossularia) Cyanidin
vation of some fruit products (pulps, musts), bleaches
Grape (red European. Vitis vinifera) Malvidin, peonidin,
anthocyanin pigments, but on heating of the fruit prduct delphinidin, cyanidin,
in vacuum the SO 2 is removed and the anthocyanin color petunidin, pelargonidin
reappears. Large concentrations of SO 2 , combined with Grape (‘Concord,’ Vitis labrusca) Cyanidin, delphinidin,
lime, decolorize anthocyanins irreversibly and are used in peonidin, malvidin,
the preparation of maraschino cherries. Anthocyanins act petunidin
as anodic and cathodic depolarizers and thereby accelerate Mango (Mangifera indica) Peonidin
the internal corrosion of tin cans. It is therefore necessary Mulberry (Morus nigra) Cyanidin
to pack anthocyanin-colored products in cans lined with Olive (Olea europea) Cyanidin
special enamel. In aging red wines anthocyanins condense Orange (‘Ruby,’ Citrus sinesis) Cyanidin. delphinidin
with other flavonoids and form polymeric (MW ≤ 3000) Passion fruit (Passiflora edulis) Delphinidin
redbrown pigments (Fig. 8). On continued polymerization Peach (Prunus persica) Cyanidin
these pigments become insoluble and form sediments in Pear (Pyrus communis) Cyanidin
bottled red wines. Plum (Prunus domestica) Cyanidin, peonidin
Anthocyanins possessing more than one acyl group Pomegranate (Punica granatum) Delphinidin, cyanidin
show extraordinary color stability over a wide pH Raspberry (Rubus ideaus) Cyanidin
range. One of them, peonidin-3-(dicaffeyl sophoroside) Strawberry (Fragaria chiloensis Pelargonidin, little cyanidin
and F. virginiaca)
5-glucoside, isolated from ‘Heavenly Blue’ morning glory
Beans (red, black; Phaseolus Pelargonidin, cyanidin,
flowers (Ipomoea tricolor), has been shown to “produce a
vulgaris) delphinidin
wide range of stable colors in foods and beverages which
Cabbage (red, Brassica oleracea) Cyanidin
have a pH range of 2.0 to about 8.0.” United States patent
Corn (red, Zea mays) Cyanidin, pelargonidin
4,172,902 covers its use as a colorant in foods.
Eggplant (Solanum melongena) Delphinidin
Onion (Alium cepa) Cyanidin, peonidin
2. Other Flavonoids Potato (Solanum tuberosum) Pelargonidin, cyanidin,
delphinidin, petunidin
Among flavonoids other than anthocyanins, the catechins,
Radish (Raphanus sativus) Pelargonidin, cyanidin
flavonols, and leucoanthocyanidins have the widest dis-