Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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delay the onset of cataract. Several vegetables, like

broccoli, spinach, parsnip, and watercress, are good

sources of vitamin E.

0016 Folic acid, commonly referred to as folate, is an

essential vitamin which is especially crucial in fetal

development in the early weeks of pregnancy. It is

essential for DNA synthesis and its action is inter-

related with that of vitamin B

. The Food and Agri-

culture Organization/World Health Organization

(FAO/WHO) expert group has recommended a daily

dietary intake of 200 mg of free folate for adults,

400 mg during pregnancy, and 300 mg during lacta-

tion. Recent studies have associated folate with a

reduced risk of cardiovascular diseases. Deep-green

leafy vegetables like spinach, kale, Swiss chard, and

parsley, and some beans are rich in folate. Light-green

leaves are generally not rich in this vitamin.

Flavor compounds

0017 The flavor compounds contribute to the overall

sensory quality of the vegetables. They are a complex

mixture of a large number of volatile compounds.

Vegetables contain some volatile flavor compounds

in the intact tissues and some are produced enzyma-

tically after the tissue is damaged or crushed. These

compounds undergo further changes after heating.

Flavor compounds of vegetables include (1) nonvola-

tiles like sugars, amino acids, fatty acids, and organic

acids and (2) volatiles like aromatic hydrocarbons,

aldehydes, acetals, ketones, alcohols, esters, and

sulfur compounds. When used as side-dishes with

cereal staple foods, these flavor compounds make

the cereal more palatable.

Dietary Fiber

0018 Leafy, root, and a few other vegetables provide diet-

ary fiber, essential for bowel movement and possibly

for the prevention of several diseases such as appen-

dicitis, colon cancer, diabetes, diverticulosis, gall-

stones, and obesity. Dietary fiber consists mainly of

cellulose, hemicellulose, pectin, lignin, and mucilage

of plants.

Toxic Substances

0019 Some vegetables contain harmful chemical com-

pounds such as trypsin inhibitors in bean seeds,

phytate in beans, and oxalate in amaranth and rhu-

barb, which pose serious nutritional problems. In

addition, chemicals such as glucosides induce toxicity

by producing hydrogen cyanide (HCN). Other toxi-

cants are nitrates in leafy vegetables, some alkaloids

in cucurbits, potato, and asparagus, and glucosino-

lates in Brassicas. These, when taken in higher

amounts, may cause harm.

0020A balanced diet should contain the amount of es-

sential nutrients needed to supply energy and prevent

nutritional deficiencies. Vegetables contain combin-

ations of nutrients and other protective substances.

Dietitians recommend an adult daily uptake of

75–125 g of green leafy vegetables, 60–80 g of other

vegetables, and 75–100 g of roots and tubers for a

balanced diet. (See Dietary Fiber: Physiological

Effects; Flavor (Flavour) Compounds: Structures

and Characteristics; Trypsin Inhibitors.)

0021With the growing consciousness of health and with

the recognition that a diet primarily of animal origin

is hazardous to health, the consumption of vegetables

has increased considerably, and vegetables have

become an important item of commerce. Vegetable

growers are able to obtain a better economic return,

and this is a great incentive for cultivation of this

commodity. Vegetables are items of daily consump-

tion and large quantities are marketed every day; the

market in vegetables can, therefore, never stagnate.

Increased demand for fresh temperate vegetables in

the more affluent countries during winter months has

created an opportunity for the tropical and subtrop-

ical countries to improve their economy by increasing

exports.

0022Many agro-based industries use vegetables as their

raw material. Tomatoes and potatoes are two vege-

tables which are processed into a wide range of prod-

ucts. Frozen vegetables are also of great commercial

importance as they retain most of the qualities of

fresh vegetables. In addition, vegetables are utilized

by many food-processing units for the production of

various vegetable sauces, fermented, and pickled

vegetables. (See Freezing: Structural and Flavor

(Flavour) Changes; Tomatoes.)

0023The importance of individual vegetables in com-

merce, and in different diets with special reference

to nutrition, is discussed under the Importance of

Specific Temperate Vegetables below.

International Trade

0024Among all the temperate vegetables discussed in this

article, potato occupies the topmost position in world

trade. According to an FAO estimate, the total world

export of potato in 1997 was 6.87 million tonnes and

the European countries ranked first, exporting 5.29

million tonnes. The next important crop in inter-

national trade is onion. Out of a total world export

of 3.23 million tonnes during 1997, the highest quan-

tity was exported by the European countries with a

share of 34.84%, followed by Asian countries with

27.83% share. Besides world trade in the fresh form

of potato, both these commodities are exported in

various processed products prepared from them.

5928 VEGETABLES OF TEMPERATE CLIMATES/Commercial and Dietary Importance

Potato chips and dehydrated onion occupy a promin-

ent position among them. In tropical countries of

Asia, mostly short day varieties of onions are

grown. These varieties are more pungent and have

higher total soluble solids than the long day types

grown in temperate countries. Because of high total

soluble solid and pungency, they store well under high

temperature conditions with less storage rot and can

stand long-distance shipping without refrigeration.

Because of these qualities, the demand for these

types is very high in world trade, particularly in

tropical countries.

0025 Cole crops and root vegetables are much in demand

in temperate countries during winter. In tropical and

subtropical countries these are grown in the open

during winter and thus the cost of production is less

compared with those grown under protective cover.

Many of these vegetables are exported from Latin

American and Asian countries to meet the demand

of the European and North American markets.

Recently, the demand for minimally processed vege-

tables has increased considerably in the developed

countries, mainly because of convenience. There is a

great potential for exporting minimally processed

temperate vegetables grown in tropical and subtrop-

ical countries during the winter season.

Importance of Specific Temperate

Vegetables

Bulb Crops

0026 Bulb crops, such as onion (Allium cepa), garlic (A.

sativum), and leek (A. porrum), are cultivated in

both the temperate and tropical regions. Leek is

particularly adapted to cold weather. (See Onions

and Related Crops.)

0027 Onions are high in energy and rich in calcium and

riboflavin (vitamin B

). The bulbs do not contain

starch and most of the carbohydrates are sucrose,

glucose, fructose, and fructosan (polymer of fruc-

tose). Green onion tops have a high carotene (pro-

vitamin A) content. Onions are an indispensable item

in every kitchen as a condiment and as a vegetable.

Green leaves and immature and mature bulbs are

eaten raw in salads or used as flavoring agents in

vegetable dishes. Multiplier onion bulbs (shallot) are

pickled in vinegar or brine. Dehydrated bulbs and

onion powder are in great demand in world trade.

The distinctive odor (pungency) of onion is due to

a volatile sulfur compound, allyl propyl disulfide.

Compounds responsible for alliaceous odors (and

flavors, at least in part) are only formed after the

onion has been cut or injured. Treatments such as

heating or freeze-drying which destroy or suppress

enzyme activity, reduce the formation of odor.

(See Freeze-drying: Structural and Flavor (Flavour)

Changes; Sensory Evaluation: Aroma.)

0028Garlic is consumed more in Asia, South America,

North Africa, and southern Europe. Garlic cloves

(bulbs) are rich in protein, carbohydrate, and some

minerals. They are used primarily as a flavoring agent

in a variety of dishes and vegetable soups, meat,

sausage, spaghetti, and vegetable curries. They are

used for the preparation of garlic bread and garlic

butter. The pungency of garlic is due to a volatile

sulfur compound, diallyl disulfide, which is produced

by the action of allinase enzyme on the amino acid,

alliin, present in the garlic.

0029The leek is an important ingredient in European

dishes and its use in North America is increasing.

Leek stalks are used as a base for soups, and they

are steamed, boiled, or eaten raw in salads. After

boiling or crushing, most of the pungent flavors

disappear and this treatment gives a mild flavor to

the product.

0030Onion and garlic have a traditional place in folk

medicine in many countries. It has been shown that

half a medium-sized raw onion a day can trigger shifts

in the ratio of ‘good’ to ‘bad’ cholesterol, replacing

a significant amount of destructive low-density

lipoprotein (LDL) cholesterol with heart-protective

high-density lipoprotein (HDL). The HDL boost is

greatest from raw white and yellow onions and is

reduced with cooking. Onion and garlic are rich

sources of quercetin, a bioflavonoid with potent anti-

carcinogenic activity. They are also known to reduce

blood sugar. An antihypoglycemic agent, diphenyla-

mine, has been identified in onion recently. The allicin

which is produced in garlic when the tissues are in-

jured by cutting or crushing has been reported to have

hypocholesterolemic action. It reduces blood sticki-

ness, thus preventing coronary thrombosis, heart

attacks, and strokes. It has been indicated that garlic

constitutents like allicin, allistalin, garlicin, diallyl

disulfide, diallyl trisulfide, and essential oils are active

against certain bacteria and other microorganisms.

(See Lipoproteins.)

Cole crops

0031Cole crops are one of the largest groups of temperate

vegetables, comprising important crops like cauli-

flower (Brassica oleracea var. botrytis), cabbage

(B. oleracea var. capitata), sprouting broccoli or

broccoli (B. oleracea var. italica), Brussels sprout (B.

oleracea var. gemmifera), kale (B. oleracea var. ace-

phala), and knol khol (B. oleracea var. gongylodes).

Cole crops are rich in vitamin C and they are good

sources of minerals. Broccoli and kale are rich in

VEGETABLES OF TEMPERATE CLIMATES/Commercial and Dietary Importance 5929

carotene (provitamin A). Several volatile sulfur com-

pounds are responsible for the characteristic flavor of

the cole crops. Dimethyl trisulfide has been indicated

as the major aroma component in cooked Brassicac-

eous vegetables. These vegetables contain compounds

known as indoles and dithiolthiones which have been

linked with the prevention of cancers of the colon,

rectum, and breast. (See Cancer: Diet in Cancer

Prevention; Colon: Cancer of the Colon.)

0032 Cabbage and broccoli are used raw in salads. Cab-

bage is used steamed or boiled alone, or in a mixture

of other vegetables as main dishes with meat or in

casseroles. Sauerkraut is the main processed product

from cabbage. Some cabbage is dried after blanching

and also pickled. Cauliflower is cooked or steamed.

It is used in a mixture with other vegetables for the

preparation of curry and fried rice in the Orient. It is

also pickled along with other vegetables. Broccoli,

Brussels sprout, and cauliflower are frozen. Broccoli

is steamed and used in the preparation of many cas-

serole dishes. It may be chopped or prepared whole or

as florets. Its versatility of use has made it a staple

item in the American diet. Knol khol is a popular

vegetable of Germany. It is used raw or uncooked,

and the tender leaves are used as greens. Cooked knol

khol is scooped out, stuffed with onion and sausage,

and then baked.

Leafy vegetables

0033 Spinach (Spinacea oleracea), Swiss chard (Beta vul-

garis var. cicla), spinach beet (B. vulgaris var. benga-

lensis), and kale (Brassica oleracea var. acephala) are

the major leaf vegetables. The first three crops belong

to the family Chenopodiaceae and the last one to

Cruciferae (Brassicaceae). Of these, spinach beet is

primarily grown in the tropics, usually during winter.

Spinach, Swiss chard, and spinach beet leaves are rich

sources of carotene and some minerals. Kale is one of

the most nutritious vegetables. It is rich in carotene

and vitamin C. Besides, there are some vegetables like

knol khol, lettuce, spinach, and turnip, the leaves of

which contain a good amount of protein. The essen-

tial amino acid composition of these leaves is given in

Table 4.

0034Spinach and Swiss chard leaves and tender petioles

are cooked, steamed, or boiled for the preparation of

dishes like pastries, souffle

s, and soups. The stems of

chard are cooked and used like celery. Sometimes

spinach and chard are cooked combined to give a

blend of their pleasant flavors. Some quantity of spin-

ach is frozen and canned. Spinach beet is a popular

leaf vegetable of the Indian subcontinent. Leaves and

petioles are cooked for preparing stews. Kale is

steamed and served with butter or vinegar, or in soups.

Pea and Broad Bean

0035Pea (Pisum sativum) and broad bean (Vicia faba) are

leguminous vegetables which are characteristically

rich in protein. Peas are high in thiamin (vitamin

), niacin, and phosphorus. Broad beans are rich in

vitamin C. The pea is one of the major vegetables of

the temperate and subtropical world. It is cooked

with other vegetables or used in soups. It is also

used in salads. In India, it is cooked with milk casein

to prepare a delicious dish. A large portion of the pea

crop is canned, frozen, or dehydrated. The broad bean

is cooked with other vegetables or processed like

peas. (See Legumes: Legumes in the Diet; Peas and

Lentils.)

0036The essential amino acid composition of pea and

broad bean has been given in Table 5. Both of them

are deficient in the amino acid tryptophan. Studies

have shown that food legumes reduce blood choles-

terol concentration and increase bowel movement.

Phytic acid (inositol hexaphosphoric acid), which is

present in mature seeds of peas and beans, can

tbl0004 Table 4 Essential amino acids content (g) of vegetable leaves

per 100 g protein

Amino acids Knol khol Lettuce Spinach Turnip

Arginine 4.8 5.6 4.8

Histidine 1.8 2.2 1.9

Isoleucine 5.3 5.1 4.8 3.8

Leucine 8.0 6.2 8.5 6.6

Lycine 8.6 5.0 6.4 5.1

Methionine 0.8 1.1 1.8 1.3

Phenylalanine 2.6 4.5 5.3 4.2

Threonine 2.1 4.3 4.6 3.8

Tryptophan 5.9 0.8 1.6 1.3

Valine 5.0 5.1 5.6 4.5

Source: Gopalan C, Sastri BVR, Balasubramanian SC, Rao BSN,

Deosthale YG and Pant KC (1999) Nutritive value of Indian Foods.

Hyderabad: National Institute of Nutrition.

tbl0005Table 5 Essential amino acid content (g) of pea and broad bean

seed per 100 g protein

Amino acids Broadbean (Vicia faba) Pea (Pisum sativum)

Arginine 8.8 9.5

Histidine 2.4 2.3

Isoleucine 4.0 4.2

Leucine 7.0 6.8

Lysine 6.4 7.5

Methionine 0.7 0.9

Phenylalanine 4.3 4.5

Threonine 3.6 4.0

Tryptophan – –

Valine 4.3 4.7

Source: Duke JA (1981) Handbook of Legumes of World Economic

Importance. New York: Plenum Press; Summerfield RJ and Roberts EH

(eds) (1985) Grain Legume Crops. London: Collins.

5930 VEGETABLES OF TEMPERATE CLIMATES/Commercial and Dietary Importance

combine with calcium and iron from other foods in

the diet and render them unavailable. (See Phytic

Acid: Nutritional Impact.)

Perennial Vegetables

0037 Major perennial vegetables are asparagus (Asparagus

officinalis), artichoke (Cynara scolymus), and car-

doon (C. cardunculus). Asparagus greens are rich in

carotene, thiamin, riboflavin, and niacin. Various

plant parts of asparagus, such as new shoots or

spears, petioles, flower buds, tubers, and roots, are

used for the preparation of different dishes. Aspara-

gus is prized for its spears. Fresh asparagus is usually

steamed or boiled. It is also frozen and canned. It is

especially rich in vitamin E and 60 g of it can provide

our daily requirement. It contains an amino acid as-

paragine which has calming properties. It is diuretic

and helps in the elimination of water through urin-

ation. It is also helpful in cleaning cholesterol from

arteries. However, in excessive amounts, it can irritate

the kidneys.

0038 In artichoke and cardoon, the edible portion consists

of fleshy bracts, receptacle, and petals. Fleshy petioles

of the cardoon are sometimes blanched to make them

more succulent. The fresh bud is usually cooked whole

and served hot or cold with melted butter, salad dress-

ing, or sauce. The canned or frozen small buds or

‘hearts’ are popular as an hors d’oeuvre. Artichoke

stimulates bile evacuation and acts as a diuretic.

Potato

0039 The potato (Solanum tuberosum) ranks first among

all the vegetables in terms of area and production in

many countries. It occupies a prominent position in

the diet as a staple food, as well as a vegetable for the

preparation of side-dishes. Potatoes are boiled, baked,

mashed, roasted, and fried (French fry). The potato

goes well in combination with most vegetables. It is

also one of the major vegetables which is processed as

chips, dehydrated, and granulated. (See Potatoes and

Related Crops: Processing Potato Tubers.)

0040 Potatoes are rich in starch, minerals, and vitamin

C. They are easily digested and assimilated, and thus

are considered as a good food for the sick and

invalids. Though the tubers contain only about 2%

protein on a fresh-weight basis, the content on a

dry-weight basis comes to about 10%, which is com-

parable to wheat flour. This makes the potato an

important source of dietary protein in countries

where consumption is high.

0041 Potato tubers when exposed to light produce an

alkaloid, solanin, which is bitter in taste and has

toxic effects when consumed in large amounts. (See

Alkaloids: Toxicology.)

Root crops

0042Though carrot (Daucus carota), radish (Raphanus

sativus), turnip (Brassica rapa), garden beet (Beta

vulgaris), parsnip (Pastinaca sativa), and rutabaga

(Brassica napus var. napobrassica) are major root

crops of the temperate region, there are distinct

tropical types of the first three crops which are

grown extensively in tropical Asia. Of all the vege-

tables, carrots, particularly yellow and orange flesh

cultivars, are the richest source of carotene (provita-

min A) which helps prevent night blindness and

cancer. The cortical region contains more carotene

than the core. Dark red cultivars, mostly of tropical

types, contain more anthocyanin pigment and con-

tribute less provitamin A to the diet. Turnip and

rutabaga are rich in vitamin C. Turnip and radish

greens are rich in provitamin A. Radish is astringent

and diuretic and is used to promote bile flow.

Garden beet is not nutritionally rich. However, it

has a number of useful medicinal properties such as

purification of blood, improving circulation, and

bowel stimulation. Its red color is due to the pigment

betacyanin, the chemical properties of which resem-

ble anthocyanin. It also contains a yellow pigment,

betaxanthin. Parsnip is rich in starch. (See Colorants

(Colourants): Properties and Determination of Nat-

ural Pigments.)

0043Carrots are primarily consumed in salads and are

used in soups, curries, stews, and pies. They are used

in the preparation of a popular sweetmeat in the

Indian subcontinent. They are frozen or pickled. It

has been indicated that there is an inverse relation-

ship between a diet which is rich in carotene and

cancer of the lung. Turnip roots are steamed or

cooked and the tender leaves, apart from use in

salads, are also cooked. In western countries, the

radish is primarily used as a salad crop. In the

Orient, it is cooked and also pickled. The rutabaga

is used almost in the same way as turnip. It is used in

salads, soups, and in baked products on account of

its pleasant flavor. Parsnip, belonging to the carrot

family, gives a pleasant flavor when steamed or

cooked, and it is used in the preparation of various

dishes. In beet, both roots and tops are steamed or

boiled, and a considerable quantity of beetroot is

canned, frozen or pickled. Beet juice is used for the

coloring of many food products.

Salad crops

0044Salad crops comprise lettuce (Lactuca sativa), celery

(Apium graveolens), chicory (Cichorium intybus),

endive (C. endivia), and parsley (Carum petroseli-

num). The lettuce is the major salad vegetable in

most of the countries of North America, South

VEGETABLES OF TEMPERATE CLIMATES/Commercial and Dietary Importance 5931

America, Europe, Australia, and New Zealand. Its

production is increasing in the Middle East, Africa,

and Japan. It is rich in provitamin A and minerals.

Leaf lettuce is more nutritious than the head types.

Celtuce (L. sativa var. augustana) is very popular in

China and Taiwan. Its succulent thick stems and

tender leaves are used raw or cooked. Celery is

primarily used as a salad crop, and is also used for

the preparation of soups, stews, and sauces. Its

seeds are used as a spice. It contains a compound,

3-n-butyl phthalide, which lowers blood pressure.

Chicory (witloof, chicon) and endive are used in

salads in Europe. The blanched cluster of leaves

(head) has a delicate flavor as compared to the

strong flavor of the green, unblanched head. It is

considered as a delicacy in France, The Netherlands,

and Belgium. The roots of chicory are dried,

roasted, and blended with coffee to give it a strong

flavor. Parsley leaves are mainly used for garnishing

and flavoring. (See Salad Crops: Dietary

Importance; Leaf-types; Root, Bulb, and Tuber

Crops.)

See also: Cancer: Diet in Cancer Prevention;

Carotenoids: Physiology; Colon: Cancer of the Colon;

Colorants (Colourants): Properties and Determination of

Natural Pigments; Dietary Fiber: Physiological Effects;

Flavor (Flavour) Compounds: Structures and

Characteristics; Freeze-drying: Structural and Flavor

(Flavour) Changes; Freezing: Structural and Flavor

(Flavour) Changes; Legumes: Legumes in the Diet;

Onions and Related Crops; Peas and Lentils; Potatoes

and Related Crops: Processing Potato Tubers; Salad

Crops: Dietary Importance; Tomatoes

Further Reading

Bose TK, Som MG and Kabir J (eds) (1993) Vegetable

Crops. Calcutta: Naya Prokash.

Choudhury B (1990) Vegetables, 8th edn. New Delhi:

National Book Trust.

Decoteau DR (2000) Vegetable Crops. New Jersey: Prentice

Hall.

Duke JA (1981) Handbook of Legumes of World Economic

Importance. New York: Plenum Press.

Gopalan C, Sastri BVR, Balasubramanian SC, Rao BSN,

Deosthale YG and Pant KC (1999) Nutritive Value

of Indian Foods. Hyderabad: National Institute of

Nutrition.

Jeana G (1991) Pigments in Vegetables. New York: Van

Nostrand Reinhold.

Nonnecke IL (1989) Vegetable Production. New York: Van

Nostrand Reinhold.

Sharon M (1999) Nutrients A to Z. London: Prion Books.

Summerfield RJ and Roberts EH (eds) (1985) Grain

Legume Crops. London: Collins.

Vaclavik VA (1998) Essentials of Food Science. New York:

Chapman and Hall.

Watt BK and Merril AL (1963) Composition of Foods –

Raw, Processed, Prepared. Agricultural Handbook

No. 8. Washington, DC: USDA.

Yamaguchi M (1983) World Vegetables. New York: Van

Nostrand Reinhold.

Cabbage and Related

Vegetables

R Fordham, Ludgvan, Cornwall, UK

P Hadley, University of Reading, Whiteknights,

Reading, UK

Introduction

0001Cabbages and closely related vegetables belonging to

the same species are collectively referred to as cole

crops, which include a number of the world’s most

commonly cultivated vegetables. They are classified

into a number of readily identifiable groups based on

morphological differences in their vegetative and

reproductive stages. This article deals with those

members primarily distinguished by vegetative differ-

ences. Members of the species differing in reproduct-

ive characters are discussed in a separate article. (See

Brassicas.) Chinese cabbage is a different species and

is dealt with separately in the article on Oriental

vegetables.

Cabbage: Brassica oleraceae Capitata

Group, Family Cruciferae

0002The cabbage is a biennial plant grown as an annual

for its edible leaves, which, at maturity, form a com-

pact head. The species is thought to have originated in

western Europe along the coast of the Mediterranean

where wild forms still occur. It subsequently spread

along the Atlantic coast as far north as Scotland.

Earliest selections were probably made to reduce the

content of bitter glucosinolates, which are at high

levels in the wild types. The crop has a long history

of cultivation; the Ancient Greeks grew it primarily

for medicinal purposes and its cultivation in Germany

took place as early as the twelfth century. Over time a

wide range of cultivars has been selected to suit dif-

ferent environments, seasons, and markets. Cabbage

production is now worldwide and, although better

adapted to cooler climates, it is also grown in tropical

regions. Data on world production are presented

in Table 1.

5932 VEGETABLES OF TEMPERATE CLIMATES/Cabbage and Related Vegetables

000 3 Although there are marked differences between

cultivars in terms of their environmental responses,

the optimum temperature for growth in cabbage is

between 16 and 18



C. Growth is arrested above



C and below 0



C, although cold-hardened plants

will survive temperatures as low as 10



C without

severe damage.

000 4 The dense terminal cabbage head is produced on a

short stem. Harvesting is usually carried out at

around the time of maximum head density, although

immature plants may also be harvested as ‘spring

greens’ in order to extend the season of supply. If

harvesting is delayed beyond maturity, further expan-

sion of the inner leaves and continuation of stem

growth will result in splitting of the head. Flowering

in cabbage, although a necessary prerequisite of seed

production, will detract from crop quality. Young

plants pass through a juvenile period during which

they are unable to flower but following this, exposure

to vernalizing temperatures of between 4 and 10



may induce premature flowering, referred to as bolt-

ing. The stem lengthens to bear a terminal raceme of

yellow to white flowers. Following pollination seed

development occurs within a fruit called a siliqua.

Normal flowering, however, usually occurs in the

second year following exposure of the mature plant

to vernalizing temperatures during its first winter in

the field. The duration of exposure required to initiate

flowering depends on the precise pattern of tempera-

tures and on the sensitivity of individual cultivars, but

generally varies between 10 and 50 days or longer.

000 5 Cabbage cultivars also differ in head shape, varying

from pointed to round; leaves may be green or red

and smooth or wrinkled. Savoy types, which are

particularly tolerant to cold conditions, have deeply

wrinkled dark green leaves. For production purposes,

cabbages are classified on the basis of their season of

maturity. The earliest types for spring harvesting may

be cut before they develop hearted heads and are then

marketed as spring greens. These are followed by a

wide range which mature throughout the summer,

fall, and winter. Winter white cultivars, often referred

to as Dutch White, have dense-hearted heads of

blanched leaves which store well.

Nutritional Value and Chemical Composition

0006The nutritional value of cabbages depends on their

vitamin and mineral contents, which vary signifi-

cantly with cultivar and method of preparation.

Carotene levels, for example, depend on the amount

of chlorophyl, and outer green leaves may contain 50

times as much as inner white ones. As a consequence,

carotene content in Savoy and kale, for example, are

significantly higher than in Dutch White cabbage.

Heat treatment will also cause changes in compos-

ition and vitamin C levels are markedly reduced by

boiling. Estimates of nutritional value and chemical

composition of cabbage and related vegetables are

summarized in Table 2.

Handling and Storage

0007Cabbages are a relatively low-value vegetable and are

normally grown on a large field scale, either from

direct drillings or transplanting. A range of cultivars

is available to provide spread in maturity dates but

the season can also be extended by growing trans-

plants under protection in glasshouses. Earliness can

also be achieved by covering field crops with plastic

film covers or nonwoven agritextiles. Under favor-

able conditions, appropriate cultivars can be har-

vested throughout the year, using Savoy types and

unhearted spring cabbages or greens to cover the

winter months.

0008Continuity of supply can also be maintained by

both cold and controlled-atmosphere storage, al-

though the latter is more commonly used for higher-

value vegetables. Winter white cabbage, for example,

can be stored for at least 6 months in cold stores at an

optimum temperature of 0–1



C, and 95% relative

humidity. Storage for longer periods can be achieved

under controlled-atmosphere conditions of lower

oxygen and higher carbon dioxide relative to ambient

conditions, although different vegetables and culti-

vars vary markedly in their response to specific levels

and off-flavors may develop. The optimum concen-

trations for cabbage lie between 2.5 and 3% oxygen

and 2–5% for carbon dioxide which, combined with

cold storage, enables white cabbage to be stored for

around 9 months.

tbl0001 Table 1 Estimated world production of cabbage

Country Production (Mt)

World total 48 872 193

China 18 502 086

India 4 200 000

Russian Federation 2 850 000

Korea, Republic of 2 755 000

Japan 2 400 000

USA 2 150 000

Poland 1 709 154

Indonesia 1 459 232

Ukraine 1 015 000

Uzbekistan 894 000

Romania 812 000

Germany 791 364

Turkey 732 000

Korea, Democratic People’s Republic 600 000

Italy 522 000

Source:FAO(1999)FoodandAgricultureOrganisation. Website:http://

apps.fao.org.

VEGETABLES OF TEMPERATE CLIMATES/Cabbage and Related Vegetables 5933

0009 Uniformity and head size are important marketing

requirements and are achieved through the appropri-

ate choice of cultivar and carefully controlled plant

spacing. Spring greens, for example, are grown at

densities of up to 40 plants per square meter, in con-

trast to 9 per square meter for hearted summer har-

vests and 3–4 for winter and fall crops. Earlier

harvests may be by selective hand-cutting, although

the majority of commercial crops are now harvested

mechanically.

Domestic and Industrial Use

0010 Cabbages may be cooked by boiling or stir-fried, or

used raw in salads and in the preparation of coleslaw.

Red types are generally sliced and pickled in vinegar.

Sauerkraut is manufactured industrially from sliced

white cabbage by controlled anaerobic fermentation

and the addition of salt. A small proportion of the

crop may be dried.

Kale:

Brassica oleraceae

Acephela Group,

Family Cruciferae

0011Kale is a biennial closely related to the cabbage,

grown as an annual for its edible shoots and young

leaves. It probably originated along with other var-

ieties of the species in western Europe, but is now

widely distributed throughout the world. It is one of

tbl0002 Table 2 Nutritional value and chemical composition of white and Savoy cabbage, curly kale, and Brussels sprouts. Values are based

on 100 g raw flesh

White cabbage Savoy cabbage Curlykale Brussels sprouts

Edible proportion 0.91 0.77 0.85 0.69

Water (g) 90.7 88.1 88.4 84.3

Total nitrogen (g) 0.23 0.33 0.55 0.56

Protein (g) 1.4 2.1 3.4 3.5

Fat (g) 0.2 0.5 1.6 1.4

Carbohydrate (g) 5.0 3.9 1.4 4.1

Energy value (kJ) 113 114 140 177

Starch (g) 0.1 0.1 0.1 0.8

Total sugars (g) 4.9 3.8 1.3 3.1

Dietary Fiber (g) (Englyst method) 2.1 3.1 3.1 4.1

Sodium (mg) 7 5 43 6

Potassium (mg) 240 320 450 450

Calcium (mg) 49 53 130 26

Magnesium (mg) 6 7 34 8

Phosphorus (mg) 29 44 61 77

Iron (mg) 0.5 1.1 1.7 0.7

Copper (mg) 0.01 0.03 0.03 0.02

Zinc (mg) 0.2 0.3 0.4 0.5

Sulfur (mg) 54 88 N 93

Chloride (mg) 40 48 68 38

Manganese (mg) 0.2 0.2 0.8 0.2

Selenium (mg) Tr (2) (2) N

Iodine (mg) 2 2 N 1

Carotene (mg) 40 995

3145 215

Vitamin D (mg) 0000

Vitamin E (mg) 0.2 0.20

(1.70) 1.00

Thiamin (mg) 0.12 0.15 0.08 0.15

Riboflavin (mg) 0.01 0.03 0.09 0.11

Niacin (mg) 0.3 0.7 1.0 0.2

Vitamin B

(mg) 0.18 0.19 0.76 0.37

Vitamin B

(mg) 0000

Folate (mg) 34 150 120 135

Pantothenate (mg) 0.21 0.21 0.09 1.00

Biotin (mg) 0.1 0.1 0.5 0.4

Vitamin C (mg) 35 62 110 115

N, no analysis available; Tr, trace.

Values in parentheses are estimated from other related data.

Average figures. The amount of carotene in leafy vegetables depends on the amount of chlorophyl, and the outer green leaves may contain 50 times as

much as inner white leaves.

Value for inner leaves.

Reproduced from Holland B, Unwin ID and Buss DH (1991) Vegetables, Herbs and Spices: Fifth Supplement to McCance and Widdowson’s. The Composition of

Foods. London: HMSO, with permission.

5934 VEGETABLES OF TEMPERATE CLIMATES/Cabbage and Related Vegetables

the hardiest of all brassicas, capable of withstanding

winter temperatures as low as 15



C. It is also toler-

ant of high summer temperatures. There are two main

groups of kale, the curly-leaved types referred to as

Scotch kales or borecole, and the broader, smooth-

leaved types. Rape or Siberian kales are similar to the

curly-leaved kales but belong to the species Brassica

napus. Unlike cabbages, kales produce no head, but

leaves are borne on a tall stem, the height of which is

dependent on cultivar. The crop is mainly used for

winter supplies when other green leafy vegetables

may be in short supply.

0012 Cultivation of the crop is similar to that for cab-

bage. Shoots and leaves of kale are cooked by boiling

in a similar manner to cabbage. They provide a

valuable source of minerals and vitamins. These are

summarized for raw curly kale in Table 2.

Brussels Sprout:

Brassica oleracea

Gemmifera Group, Family Cruciferae

0013 The Brussels sprout is a single-stemmed, tall biennial

growing to a height of around 1 meter in its first

season. The main edible portions of the crop are the

small, tightly formed axillary buds that develop in the

axils of the expanding leaves. Its loose head of large

leaves may also be used as a substitute for cabbage.

Flower production in Brussels sprouts is similar to

that for cabbage, being triggered by exposure of

mature plants to relatively low temperatures. Culti-

vars vary in their sensitivity to vernalizing tempera-

tures, but Brussels sprouts generally require a longer

period of exposure than cabbage, ranging from

around 50 to 80 days. The crop has developed from

the wild cabbage and is believed to have originated in

Belgium where it was cultivated during the nineteenth

century. Its cultivation has spread to other European

countries: production is carried out on a relatively

large scale in the UK. Its importance is more limited

outside Europe. In the USA it is mainly cultivated in

California.

0014 Brussels sprouts are adapted to relatively cool

conditions, and in warmer regions the axillary buds

may develop into loose sprouts, in contrast to the

preferred tightly formed round buds. Cultivars

have been selected to provide a spread in harvests

and later-maturing ones are able to withstand

temperatures down to 10



C. Cultivar selection for

sprout uniformity has been achieved for use in mech-

anical harvesting.

Food Value and Chemical Composition

0015 In comparison with other Brassica crops, only a rela-

tively small portion of the total plant is consumed.

The composition of the edible sprouts is indicated in

Table 2. Mineral and vitamin content determines

their main value.

Handling and Storage

0016The cultivation of Brussels sprouts is similar to that

of cabbage and other Brassica species. Crops may

be grown either from direct seeding or from trans-

planted seedlings raised in open seed beds or, more

generally, under protection. Typically, seeds are

sown in early spring and harvesting is carried out

from fall until the following spring. Continuity

of production is achieved primarily through choice

of cultivars, but raising transplants under protection

enables an advancement of the earlier crops. The

sprouts on older cultivars develop from the base of

the stem upwards, necessitating selective harvesting

by hand. Modern hybrid cultivars, however, mature

more uniformly and commercial production is now

mainly conducted using mechanical harvesters.

0017Sprouts are trimmed and marketed loose. Short-

term storage in cold stores at 0–1



C and high humid-

ity can be used to maintain freshness.

Domestic and Industrial Use

0018Brussels sprouts are cooked by boiling. Processing is

primarily by freezing, although a small proportion of

the crop is canned.

See also: Brassicas; Vegetables of Temperate

Climates: Oriental Brassicas

Further Reading

Hardy FS and Watson GD (1982) The Complete Guide

to Commercial Vegetable Growing. London: Frederick

Muller.

Holland B, Unwin ID and Buss DH (1991) Vegetables,

Herbs and Spices: Fifth Supplement to McCance and

Widdowson’s The Composition of Foods. London:

HMSO.

Huxley AJ, Griffiths M and Levy M (eds) (1992) The

New Royal Society Dictionary of Gardening. London:

MacMillan.

Nieuwhof M (1969) Cole Crops – Botany, Cultivation and

Utilization. London: Leonard Hill.

Nonnecke IL (1989) Vegetable Production. New York: AVI.

Rubatzky VE and Yamaguchi MAS (1997) World Vege-

tables – Principles and Nutritive Values, 2nd edn.

Connecticut: AVI.

Salunkhe DK and Kadam SS (eds) (1998) Handbook of

Vegetable Science and Technology: Production, Compos-

ition, Storage and Processing. New York: Marcel Dekker.

Splittstoesser WE (1990) Vegetable Growing Handbook –

Organic and Traditional Methods. New York: Van Nos-

trand Reinhold.

Thompson HC and Kelly WC (1957) Vegetable Crops. New

York: McGraw-Hill.

VEGETABLES OF TEMPERATE CLIMATES/Cabbage and Related Vegetables 5935

Weichmann J (ed.) (1987) Postharvest Physiology of

Vegetables. New York: Marcel Dekker.

Wein HC (1997) The Physiology of Vegetable Crops.

Wallingford, Oxon, UK: CAB International.

Wein HC and Wurr DCE (1997) Cauliflower, broccoli,

cabbage and Brussels sprouts. In: Wien HC (ed.) The

Physiology of Vegetable Crops. Wallingford, Oxon, UK:

CAB International.

Broccoli-type Brassicas See Brassicas

Leaf Vegetables

R Fordham, Ludgvan, Cornwall, UK

P Hadley, University of Reading, Whiteknights, UK

Introduction

0001 In addition to the diverse selections of the species

Brassica oleraceae which include nonheading leafy

members, there are other species within the genus

Brassica and also in the family Chenopodiacea which

are cultivated as vegetables principally for their edible

foliage.

Spinach (

Spinacia oleracea

): Family

Chenopodiacea

0002 Spinach is an annual crop grown for its edible leaves. It

initially develops as a rosette of leaves on a short stem.

Following stem elongation, branching occurs from

leaf axils, from which further laterals develop. It is

believed to have originated in central Asia and there

are records of its cultivation in China in the seventh

century and in Europe in the fourteenth century. The

Moors introduced it to Spain and the word ‘spinach’ is

derived from the Spanish hispania. It is now widely

cultivated, particularly in the USA. It has a long history

of cultivation. Recent production statistics for the

principal growing areas are summarized in Table 1.

0003 It is a cool-season crop and grows best at average

temperatures in the range 16–18



C. Young plants can

withstand freezing temperatures down to 9



Flowering is induced by long day conditions; the

critical day-length ranges from 12.5 to 15 h depending

on cultivar and temperature. High temperatures can

also cause premature flowering or bolting. A combin-

ation of cold exposure followed by high temperatures

and long days causes rapid bolting with consequent

cessation of leaf growth. Most cultivars produce

between 22 and 26 leaves.

0004 The species is mainly dioecious, producing male

and female flowers on separate plants, although

monoecious plants occur.

0005Cultivars differ in day-length response and also in

their leaf morphology, which may be either smooth or

wrinkled (savoyed).

Nutritional Value and Chemical Composition

0006Spinach is rich in vitamins and is particularly high in

carotene, a precursor of vitamin A. It is also rich in

iron and calcium, but the calcium is said to be un-

available as it unites with oxalic acid to form calcium

oxalate. Table 2 summarizes the nutritional value

and composition of raw spinach leaves. Spinach

leaves contain relatively high levels of nitrate (1075–

2300 p.p.m.), although these are influenced by a

number of factors, including cultivar, fertilizer regime,

growing temperatures, and nitrate reductase activity.

It has been suggested that frequent consumption of

leafy vegetables containing high levels of nitrate may

be hazardous as a result of the nitrate being reduced

to nitrite by saliva and the upper gastrointestinal tract.

It has been shown that nitrate levels are reduced by

exposure of light prior to harvesting and that levels

increase during storage. Thus, agronomic practices

can have a significant influence on the levels of nitrate

in the marketed leaves. Processing and culinary treat-

ment will also affect levels of nitrates and other com-

ponents. For example, canning and freezing at 18



can lead to cell rupture and hence ion loss. This

has been reported particularly in relation to nitrate

tbl0001Table 1 Estimated world production of spinach (Mt)

World 8 031 923

China 6 162 000

USA 354 390

Japan 330 000

Turkey 191 000

France 130 000

Korea, Republic of 125 000

Italy 85 367

Pakistan 73 788

Indonesia 65 000

Germany 59 890

Belgium–Luxembourg 58 000

Spain 50 000

Source: Food and Agriculture Organization (2001) http: //

www.nal.usda.gou/fric/foodcomp.

5936 VEGETABLES OF TEMPERATE CLIMATES/Leaf Vegetables

reduction. Sun-drying of spinach before storage is

carried out in a number of developing countries but

the practice markedly reduces carotene content.

Handling and Storage

0007 Leaf production is at its optimum just below the

critical day-length and thus appropriate cultivars are

needed to suit latitude and season of production. The

crop is established from direct seeding. For overwin-

tering, a hardier form of spinach having prickly seeds

is preferable. Spinach leaves can either be harvested

individually as required or the entire shoot can be

cut off just above ground level, leaving the plant to

produce a new growth under favorable conditions.

Mechanical harvesting is used commercially, particu-

larly for the processing industries.

000 8 Continuous refrigeration just above 0



Cfrompack-

aging through to retail is desirable. Hydrocooling or

vacuum cooling should be carried out as soon as prac-

tical after harvesting in order to remove field heat.

Storage at ambient temperatures for as little as 24h

can lead to significant losses in ascorbic acid and vita-

min A. Controlled-atmosphere storage can prolong the

shelf-life of spinach by about 1 week at 5



Domestic and Industrial Use

0009The leaves are prepared by boiling and can also be

used raw in salads. The crop is also processed by both

freezing and canning.

New Zealand Spinach (

Tetragonia

tetragoniodes

): Family Aizoaceae

0010New Zealand spinach is a minor crop unrelated to

true spinach. It is a perennial, trailing vine reaching

2 m in length and cultivated for its edible young

shoots and dark green succulent leaves. It is indigen-

ous to New Zealand and the south and western

coastal regions of Australia and Tasmania and was

introduced to England in the eighteenth century. It

has the advantages of being drought-resistant and

heat-tolerant but is not as hardy as spinach and is

therefore established in the spring after the risk of

frost. It can be raised from either direct seeding or

from transplants. Seed germination is slow. Harvest-

ing commences about 70 days after sowing by cutting

off the terminal 7–8cm of shoot growth. This may

be repeated two or three times during the season

following regrowth. The crop is a useful substitute

for spinach in hot dry weather. Young shoots are

edible either raw or cooked. Information on the

nutritional value and chemical composition of New

Zealand spinach is included in Table 2.

Swiss Chard

Beta vulgaris

ssp.

cicla

Family Chenopodiacea

0011Swiss chard was first recorded in the Mediterranean

region and Canary Islands and was popular as long

ago as 350 bc. It was introduced to the USA in 1806

by Swiss settlers.

0012Swiss chard is a biennial cultivated as an annual for

its edible leaves. It has a number of synonyms, includ-

ing silver chard, seakale beet, silver beet, spinach

beet, and perpetual spinach.

0013There are a range of types, including those with

dark green spinach-like leaves to examples with large

crisp crinkly leaves, pronounced fleshy midribs, and

swollen petioles. The latter types are referred to as

chards and after removing the leaf lamina the central

portions are used asa separate vegetable which may be

cooked and served like asparagus. Leaf stalks occur in

a range of colors, including white, pink, red and silver.

tbl00 02 Table 2 Nutritionalvalueandchemicalcompositionofspinach,

NewZealandspinach,andSwisschard. Valuesarebasedon

100grawflesh

SpinachNewZealand

spinach

Swisschard

Proximates

Water(g)91.5894.0092.66

Energy(kJ)925979

Protein(g)2.861.501.80

Totallipid(fat)(g)0.350.200.20

Carbohydrate,by

difference(g)

3.502.503.74

Fiber,totaldietary(g)2.7N1.6

Ash(g)1.721.801.60

Minerals

Calcium,Ca(mg)995851

Iron,Fe(mg)2.710.801.80

Magnesium,Mg(mg)793981

Phosphorus,P(mg)492846

Potassium,K(mg)558130379

Sodium,Na(mg)79130213

Zinc,Zn(mg)0.530.380.36

Copper,Cu(mg)0.1300.0930.179

Manganese, Mn (mg) 0.897 0.639 0.366

Selenium, Se (mg) 1.0 0.7 0.9

Vitamins

Vitamin C total ascorbic

acid (mg)

28.1 30.0 30.0

Thiamin (mg) 0.078 0.040 0.040

Riboflavin (mg) 0.189 0.130 0.090

Niacin (mg) 0.724 0.500 0.400

Pantothenic acid (mg) 0.065 0.312 0.172

Vitamin B

(mg) 0.195 0.304 0.099

Folate, total (mg) 194 15 14

Vitamin B

(mg) 0.00 0.00 0.00

Vitamin A (mg RE) 672 440 330

Vitamin E (mg ATE) 1.890 N 1.890

N, no analysis available.

RE, retinol equivalents; ATE, alpha-tocopherol equivalents.

Source:USDepartmentofAgriculture(2001)http://www.nal.usda.gov/

fric/foodcomp.

VEGETABLES OF TEMPERATE CLIMATES/Leaf Vegetables 5937