Food Biochemistry and Food Processing

534 Part V: Fruits, Vegetables, and Cereals

Flavonols

The best-known flavonols are quercetin and kaem-
pferol. Quercetin is ubiquitous in fruits and vegeta-
bles. Kaempferol is most common among fruits and
leafy vegetables. In fruits, flavonols and their glyco-
sides are found predominantly in the skin. Myricetin
is found most often in berries.

Anthocyanins

Anthocyanins (Table 22.6) often occur as a complex
mixture. Grape extracts can have glucosides, acetyl
glucosides, and coumaryl glucosides of delphini-
din, cyanidin, petunidin, peonidin, and malvidin. The
color of anthocyanins is pH dependent. An antho-
cyanin is usually red at a pH of 3.5, becoming color-
less and then shifting to blue as the pH increases.
Fruit anthocyanin content increases with maturity.
In stone fruits (peaches and plums) and pome fruits
(apple and pears), anthocyanins are restricted to the
skin, whereas in soft fruits (berries), they are pres-
ent both in skin and flesh. Anthocyanins are used as
coloring agents for beverages and other food prod-
ucts.

Flavans

Flavans are what was once called catechins, leu-

coanthocyanins, proanthocyanins, and tannins. They

occur as monoflavans, biflavans, and triflavans. Mon-

oflavans are found in ripe fruits and fresh leaves.

Biflavans and triflavans are found in fruits such as ap-

ples, blackberries, black currants, cranberries, grapes,

peaches, and strawberries.

REFERENCES

FURTHERREADINGMATERIALS

Arthey D, Ashwurst PR. 2001. Fruit Processing: Nutri-

tion, Products and Quality Management. Aspen Pub-

lishers, Gaithersburg, Maryland. 312 pages.

Enachescu DM. 1995. Fruit and Vegetable Processing.

FAO Agricultural Services Bulletin 119. FAO, 382

pages.

Jongen WMF. 2002. Fruit and Vegetable Processing:

Improving Quality (Electronic Resource). CRC, Boca

Raton, Florida.

Salunkhe DK, Kadam SS. 1998. Handbook of Veget-

able Science and Technology: Production, Composi-

tion, Storage and Processing. Marcel Dekker Inc.,

New York. 721 pages.

Table 22.6.Anthocyanins of Selected Fruits

Anthocyanin
Fruit Identification Peak Area
Apple Cyanidin 3-arabinoside 22
6
Cyanidin 7-arabinoside or Cyanidin 3-glucoside 27
15
Cyanidin 3-galactoside 260
69
Cherry Cyanidin 3-glucoside 189
40
Cyanidin 3-rutinoside 1320
109
Peonidin 3 rutinoside 47
36
Grape Cyanidin 3-glucoside 121
33
Delphinidin 3-glucoside 586
110
Malvidin 3-glucoside 2157
375
Peonidin 3-glucoside 478
92
Nectarine Cyanidin 3-glucoside 322
51
Peach Cyanidin 3-glucoside 180
43
Plum Cyanidin 3-glucoside 42
5
Strawberry Cyanidin 3-glucoside 70
18
Pelargonidin 3-glucoside 1302
29
Pelargonidin 3-glycoside 78
9
Source:Reprinted with permission from Van Gorsel et al., J Agr Food Chem, 1992, 40:784–789. Copyright, American
Chemical Society.