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

Подождите немного. Документ загружается.

opportunities to expand markets for fresh sweet cher-

ries and for some sour cherry products.

Cherry Taxonomy and Types

0002 Commercially, the two most important cherry species

are: sweet cherry, Prunus avium, L. and sour cherry,

Prunus cerasus L., both tree fruits native to south-

eastern Europe and western Asia. They are closely

related, graft-compatible, and hybridize to form inter-

specific (Duke) cultivars. Sweet cherry (diploid, with

a base chromosome number of 8, and a somatic

number of 16) probably originated somewhere

between the Black Sea and the Caspian Sea, but it

spread into Europe in ancient times. Sour cherry

(tetraploid, with a base chromosome number of 16,

somatic chromosome number of 32) is native to the

same areas as sweet cherry, and there is good evidence

that crosses between Prunus avium and the ground

cherry, P. fruticosa Pall, gave rise to sour cherry.

There are several other cherry species, but most, e.g.,

Nanking cherry (Prunus tomentosa), have limited

commercial value as fruits.

0003 Sweet cherries can be divided into two major types

based on fruit characteristics. Heart-type cherries are

ovoid or heart-shaped with a relatively soft flesh,

often ripening early. Most of the commercially im-

portant cultivars, however, are of the Bigarreau type

with firmer, crisp-fleshed fruit, ripening mid to late

season. Fruit flesh may be red or yellow, and the skin

may be dark (red to nearly black) or light (yellow–red

to yellow–white).

0004 Many sweet cherry cultivars grown throughout the

world originated in Europe, but a number of im-

portant cultivars were selected or bred in local cherry

districts. European cultivars grown in the USA

are Napoleon (Royal Ann), Black Tartarian, Eagle,

Early Purple, Early Rivers, Elkhorn, Hedelfingen,

Knight’s Early Black, Lyon, and Schmidt. The

cultivars Windsor, Van, Sam, Vista, Victor, Sue,

Vega, Summit, and Stella were developed in Canada.

Chinook and Rainier were developed in Washington.

Bing, Lambert, Black Republican, Corum, and

Hoskins were selected and developed in Oregon.

Chapman, Burbank, Bush Tartarian, and the new

cultivars Mona, Larian, Jubilee, Berryessa, and Bada

originated in California. Recent introductions include

Ulster and Hudson from New York, and Angela from

Utah.

0005 The most important sweet cherry cultivars in the

western USA, where about 80% of the US crop is

produced, have been dark-fruited, crisp-fleshed culti-

vars: Bing (the leading cultivar in North America),

Van, and Lambert. But others may be available be-

cause of their use as pollinators or as the result of

recent fresh market demand for large, light-colored,

and crisp fleshed fruits from cultivars like Rainier.

Firmness, size, color, and soluble solids are all im-

portant market considerations, and growers in

regions where summer rains are prevalent, e.g., the

eastern USA and eastern Europe, are at a disadvan-

tage because the main cultivars are often the softer

fleshed, rain-cracking resistant types, e.g., Emperor

Francis, Hedelfingen, and Schmidt. In these regions,

light-fleshed cultivars, Rainier, Napoleon (Royal

Ann), Corum, and Emperor Francis, are best for

making into maraschino cherries (because the pig-

ment is undesirable), but a few are nevertheless

grown for the fresh market. Napoleon is also used

for canning. Bing is mainly a fresh-market cultivar,

and Lambert is used both for canning and fresh

market. Black Republican and other very firm, dark

cherries are good for freezing.

0006Sour cherry fruit are generally soft, juicy, and de-

pressed-globose in shape, but colors may range from

the Morello types, with red to dark red flesh and

juice, to the Amarelle types with an almost colorless

juice and flesh.

0007Although new cultivars are being tested, there are

only a few sour cherry cultivars commonly grown in

North America, ranging from the light red Early

Richmond, the medium red-skinned Montmorency,

to the late dark red English Morello, but Montmor-

ency is still the standard. In western Europe, Schat-

tenmorelle and Sternsbaer are common, but many

others are grown in Russia, the former Yugoslavia,

Romania, and Hungary. Most, unlike sweet cherry,

are more or less self fertile and generally do not

require pollinators. Almost all of those grown in the

USA and western Europe are harvested mechanically

and sold for processing, primarily as a frozen or

canned ingredient for use in manufactured food

products such as pies but more recently as a dried

fruit product, and in Europe and other areas, several

other uses have been developing for juice, liqueur, and

marmalade production, and combinations with

yogurt.

Production Areas

0008The USA, Russia, and Germany are large producers

of both sweet and sour cherry (Table 1). In some

areas of northern Europe, sour cherries are, after

apples, the second most important fruit grown.

Otherwise, within Europe and western Asia, sour

cherry production is concentrated in the Ukraine,

Russia, Poland, Turkey, and Germany, whereas

sweet cherry production is concentrated in Iran,

Turkey, Italy, and Germany. Sweet cherry production

is increasing in the Southern Hemisphere, in New

1136 CHERRIES

Zealand, Australia, and Chile, for shipment to north-

ern markets in their winter season. In the USA, sweet

cherry production is mostly in the west, primarily in

Washington, but also in Oregon and California. Most

USA sour cherry production occurs near the Great

Lakes, primarily in Michigan with 70–75% of the

US crop, which, with New York, Wisconsin, and

Pennsylvania totals 90–95% of the US crop.

0009Maximum world production values for sweet

and sour cherry are approximately 1 450 000 and

1 600 000 tonnes, respectively. Wide annual supply

fluctuations, especially regionally, in both sweet and

sour cherries characterize production and create high

risks in product availability and price change for

producers, processors, and marketers. The annual

US sour cherry production has ranged, for example,

from 63 600 to 141 000 tonnes, but there has been a

gradual downward trend in average production since

the mid-1960s to about 125 000 tonnes during recent

years, with a farm value of about $50 million, but the

processed value is at least three times that. Sweet

cherry production, however, is increasing, especially

as markets develop in Japan and the Far East of the

Pacific Rim for fresh cherries grown in the western

USA and elsewhere.

Growth and Management

Flowering and Fruit Set

0010Sweet cherry flowers are in clusters of two to four,

usually borne laterally on short spurs on 2-year-old

twigs or near the base of longer 1-year-old shoots.

Floral initiation takes place in July, after the crop is

harvested, and only on buds where the subtending

leaves opened relatively early in summer. Flower

buds are of the unmixed type and do not give rise to

a lateral or bourse shoot. As a result, flowering spurs,

unlike those on apples and pears, do not remain

productive. Flowers generally have a single pistil

but, in very hot summers, may form two pistils that

result in undesirable double fruits. With few excep-

tions, e.g., ‘Stella’ (and its progeny), and the new

‘Lapins’ and ‘Sweetheart’ cultivars, commercial

sweet cherries are self-sterile (self-incompatible), and

therefore require another cultivar for pollination.

There are, however, intrasterile groups, where none

of the group will cross-pollinate any other member of

the group. Bing, Lambert, and Napoleon are one such

group.

0011Sour cherry flowers develop much like sweet

cherry, with buds of two to four flowers on either

spurs or lateral buds. Sour cherry cultivars range

from compatible to self-incompatible. Montmorency,

for example, is only partially compatible, but is

always grown without a pollinator. Fruit set, how-

ever, clearly limits yield or the fully incompatible

cultivars, but overcropping may occur in other culti-

vars with excessive flowering or fruit set resulting in

too few leaves or leaf buds to develop fruit of an

adequate size and quality.

0012In both sweet and sour cherry, flower development

and fruit set may frequently be harmed by late frosts,

tbl0001 Table 1 Production and utilization of sweet and sour cherries

internationally (derived from FAO 1996–2000 statistics)

Country 1000s of tons

peryear

Percentage

destined

for processing

Sweet Sour Sweet Sour

Argentina 6.0 30–35

Armenia 1.8 3.0 0 0

Australia 6.9 0

Austria 24.7 4.5 10–15 20–30

Azerbaijan 10.8 5.2 0 0

Belgium/Luxemburg 6.3 0

Bulgaria 45.3 11.9 40–50 90–100

Byelorussia 15.8 29.4 0 0

Canada 5.4 6.4 20–25 100

Chile 23.4 35–50

People’s Republic

of China

1.3 0

Czech Republic 12.6 7.3 10–20 30–40

Denmark 4.4 0

Estonia 0.9 0.1 0–5 0–5

France 63.8 25–30

Georgia 17.0 23.3 0 0

Germany 122.4 72.0 30–35 10–15

Greece 47.8 2.9 10 100

Hungary 20.6 53.8 60–70 80–90

India 4.0 10

Iran 217.7 42.1 0

Israel 1.1 0

Italy 132.7 6.9 5–10

Japan 17.0 35–50

Kazakhstan 5.4 0

Kyrgyzstan 3.5 9.0 0 0

Latvia 6.0 0

Lithuania 17.0 2.6 10–20 90–100

Moldavia 6.7 9.2 20 90

New Zealand 1.3 0

Norway 4.5 0

Poland 36.8 143.8 10–30 90

Portugal 6.9 0.6 15–20

Romania 78.1 20 80

Russia 64.2 154.0 25–35 65–75

Slovak Republic 5.7 1.5 70 90

Spain 81.7 1.5 5–10

Switzerland 20.5 60–70

Tajikistan 3.5 3.4 0 0

Turkey 200.0 124.0 20–25 95–100

Ukraine 61.3 193.4 30–40 95–100

UK 1.5 0

USA 188.3 128.8 45–55 100

Uzbekistan 10.9 14.0 0

Former Yugoslavia 26.9 68.9 5–10 95–100

CHERRIES 1137

although sour cherry is hardier and generally blooms

later than sweet cherry. Wide annual supply fluctu-

ations are consequently common in major growing

areas for both species owing to spring frosts or to low

midwinter temperatures where a lack of wood hardi-

ness is a contributing factor. Sweet cherries are less

hardy than apples, but some sour cherry cultivars

may be as hardy as the apple cultivars McIntosh or

Northern Spy. In addition, the best-quality sweet

cherry cultivars tend to be more susceptible to rain

cracking, and do best in regions with dry summer

growing conditions. Fruit also develop a good quality

in regions often too cool for peaches or apricots. The

climate also dictates that cherries be grown where

winter chilling temperatures (about 1000 h for most

sweet cherries, longer for sour cherry) are adequate to

break rest, and so cherry culture is generally limited

to cooler temperate regions.

Tree Size and Rootstocks

0013 Tree size plays a central role in production of

quality fruit. Dwarf trees have many advantages:

light penetrates better, favoring photosynthesis, and

the tree produces more and better fruit; spraying can

be done more efficiently, usually with a reduced use of

chemicals; and dwarf trees are easier to harvest. Cher-

ries are no exception, but dwarfing rootstocks have

not been available for either sweet or sour cherry. The

common rootstocks, ‘Mazzard’ and ‘Mahaleb,’ only

slightly affect tree size, if at all. ‘Colt’ is similar, and

may be somewhat drought- and cold-susceptible.

Recently, however, dwarfing rootstocks have been

developed in several breeding programs, and these

are being tested. For example, of 17 cherry rootstocks

developed in Giessen, Germany, most produce rela-

tively large trees, but two of these rootstocks give

trees about 25% of the standard, and several root-

stocks developed in Belgium may also be promising.

Harvesting and Handling

0014 Sweet cherries are almost all hand-harvested, particu-

larly those intended for the fresh market. Avoiding

pitting and bruising throughout harvest, sorting, and

packing is a major problem in delivering high-quality

fruit to the fresh market. The susceptibility of some

white- or yellow-fleshed cultivars to bruising may

even require field packing to minimize loss. Mechan-

ical harvesting of sour cherries for processing, how-

ever, has been a major technological development

that substantially reduces grower costs. A grower

and their family plus a group of six to eight high-

school students can harvest mechanically as much

as 200–300 hand pickers formerly did. The results

include huge savings in direct labor costs, large

reductions in housing costs, plus substantial savings

in direct labor fringe costs. The US sour cherry indus-

try became essentially completely mechanically har-

vested during the 1970s, although there have since

been additional improvements in equipment and

techniques.

0015Some aspects of cherry processing have also

changed substantially, which has led to greater effi-

ciencies and product quality in the cherry industry.

Almost all sour cherry processors have adopted elec-

tric-eye sorting equipment that substantially reduces

in-plant sorting labor, and destemming equipment

efficiently removes the stems from mechanically

harvested cherries. Although picking of sweet cherries

for the fresh market is still by hand, subsequent hand-

ling has been improved dramatically very recently

with the substitution of hydraulic flumes for conveyor

belts to reduce bruising and pitting throughout

sorting and packing.

Quality Factors

0016Soluble solids (primarily hexose sugars and sorbitol)

and fruit color (depending on the type) are the best

indicators of quality for both sweet and sour cherry,

although the fruit acid level may be important in sour

cherry. Except for soluble carbohydrates, vitamins A

and C, and certain flavonoids that may be important

as antioxidants in some cultivars, cherries are rela-

tively low in nutrients, but calcium, iron, magnesium,

phosphorus, and copper contents are high compared

with apple, peach, grape, and strawberry. High-

quality sour cherry fruit typically have at least 15%

soluble solids, whereas sweet cherries should be

nearer 20% (or higher). Standards for harvest and

marketing may, however, often be lower. Optimum

conditions also often vary with use. To facilitate

brining (bleaching in sulfur dioxide solutions for mar-

aschino cherries), fruit may be picked prematurely

before color and soluble solids are adequate for the

fresh market. Stem-fruit removal force is carefully

monitored for sour cherries that will be mechanically

harvested, and abscission can be brought on by

treatment with ethephon, which releases ethylene,

expediting abscission and fruit drop in response

to mechanical shaking.

Disorders, Diseases, and Pests

Disorders

0017In processing brined sweet and sour cherries, the

solution pocket problem involves subepidermal splits

in the flesh that fill with brine solution and ruptured

1138 CHERRIES

cell contents. The time of harvest, degree of turgidity

at brining, temperature, or any procedures that

reduce either the sugar or water content of the fruit

will tend to reduce the problem.

0018 Rain cracking (swelling followed by rupture of

the epidermis) of sweet cherries occurs mostly

during the harvest period when the fruit is mature or

almost mature and has been wet with rain for some

time. The primary cause is absorption of water dir-

ectly through the skin of the fruit, and not through the

root system. Cultivar-cracking susceptibility has been

tested extensively. In testing, Bing, one of the best

quality cultivars, was worst, followed by Napoleon,

Lambert, Emperor Francis, Giant, Schmidt, Yellow

Spanish, and Montmorency, which did not crack. In

another ranking, Bing invariably cracked very badly,

and was followed by Lambert, Giant, Gil Peck, and

Hedelfingen. In yet another test, Van, Merton Glory,

Vega, and Vista were very susceptible, whereas Em-

peror Francis, Schmidt, and Sam were less suscep-

tible, and Sue, Kristin, Ulster, and Early Rivers were

least susceptible. From the long-range viewpoint,

breeding programs under way ultimately may pro-

duce desirable crack-resistant cherries. Cracking

may be reduced by some chemical treatments, e.g.,

rain activated calcium sprayers, but results with hor-

mones, auxin (NAA, naphthalene acetic acid) and

gibberellin (GA

) applications are equivocal. In

some parts of the world, e.g., Norway, covering

trees with plastic film has been widely used to avoid

cracking, and the method is being tested elsewhere

despite the high costs.

0019 Pitting of sweet cherry is a condition in which areas

near the surface of the fruit become sunken, forming

dimples or pits, and may occur before or after har-

vest, and there are at least three different sources:

usually from bruising during handling, but also from

feeding by sucking insects such as the soldier bug, and

perhaps from physiologic injuries, e.g., adverse low-

temperature stress during postharvest cooling or

growing conditions.

Diseases

0020 Bacterial canker, one of the most important sweet and

sour cherry pathogens, is caused by two different

pathogens, Pseudomonas syringae and P. morspru-

norum, and is characterized by oozing of gum (gum-

mosis) at infection sites. Disease development is most

prevalent during the cool, wet periods of early spring.

Crown gall, caused by Agrobacterium tumefaciens,

can affect sweet and sour cherry rootstocks and

is characterized by galls forming usually near infec-

tion sites caused by wounds, sometimes man-made,

e.g., cultivation injuries, or resulting from damage

from subterranean chewing insects or rodents. Some

rootstocks, however, are only moderately susceptible,

and some hybrids may be tolerant. Brown rot, caused

by the fungi Monilinia fructicola or M. laxa, affects

both sweet and sour cherries and reduces yield in

infecting and decaying blossoms, twigs, and fruit.

Fruit decay after harvest is also a problem. The

fungi persist in mummified fruit on the tree and

the ground, and infection continues from these inoc-

ula the following spring. Growing regions with cooler

and drier summers provide some relief. Cherry leaf

spot, Blumeriella jaapii (Coccomyces hiemalis), is the

most serious disease affecting sour cherry and most

ground cherries. Infection occurs in the spring on

expanding leaves and continues throughout the

season under favorable conditions, e.g., high humid-

ity. Severely infected leaves become chlorotic and

abscise, and if defoliation is severe, fruit may not

ripen properly, and tree vigor and hardiness are re-

duced. Powdery mildew (Podosphaera ocyacanthae)

is similar. Other fungal pathogens may sometimes be

important, causing blights, crown or root rots, and

replant (orchard reestablishment) problems. Cherry

dieback is thought to be a complex of several dis-

orders, one of which may be mycoplasma. X-disease,

leafhopper-transmitted and often devastating, is also

due to mycoplasma.

0021Several viruses cause poor vegetative growth,

reduce yields, and may even result in tree death, but

others are symptomless. Among the most severe is

Prunus Necrotic Ringspot Virus, which is pollen

transmitted and present in all cherry growing areas

of the world. Little Cherry (Prune Dwarf) disease is

another pollen-transmitted virus and very destructive.

Prunus stem pitting disease is caused by the tomato

ringspot virus and is spread by nematodes.

Pests

0022Bird damage can be very serious, and some areas may

require protective netting to reduce predation. The

major insect pest, the cherry fruit fly passes the winter

in the soil as a pupa, adult flies emerge in late spring,

and females feed on the surfaces of leaves and fruit

and lay eggs in the nearly ripe fruit. On hatching, the

larvae (maggots) feed on the fruit flesh. The larvae are

easily killed by holding fruit near 0



C, but fumiga-

tion, until recently carried out most often with methyl

bromide, may be required to meet quarantine restric-

tions for shipping overseas. Other pests include black

cherry aphid, plum curculio, European red mite,

peach tree borer, and two-spotted mite.

CHERRIES 1139

Economic Problems and Future

Developments

0023 Although the sour cherry industry is facing a serious

problem of excessive productive capacity in some

years and persistent oversupplies, this industry has

adopted new technologies and practices in the last

10 years that substantially improve its cost efficiency

and productivity. Much of the newly planted acreage

uses efficient trickle irrigation and closely planted

orchard systems that also involve hedging techniques.

These recent new techniques, especially in combin-

ation, provide large increases in yields per hectare and

hence substantial reductions in costs.

0024 Considerable genetic diversity still exists in Eastern

Europe and Russia, the center of origin for both sour

and sweet cherries. Although breeding programs have

been limited, exploiting that diversity should do

much to overcome the growing, handling, and pro-

cessing problems that face growers using the industry

standards, the sweet ‘Bing’ and the sour ‘Montmor-

ency’ in the USA. Sweet cherry growers especially

need dwarfing rootstocks and spur types for growth

control, and all growers need disease and pest resist-

ance, less self-sterility, and cultivars with a range

of maturities so that there are longer seasons for

fresh markets. Sweet cherry growers also need rain-

cracking resistance and, for postharvest fresh-market

quality, resistance to bruising. Sour cherry growers

need new cultivars for diversifying and strengthening

marketing options, e.g., fresh and frozen juice prod-

ucts, dyes for cosmetics and the food processing in-

dustry, and dry stem scars and small freestone pits to

facilitate handling and processing. A combination of

new marketing strategies and products for sour cher-

ries and advances in breeding of both sweet and sour

cherries would clearly benefit the economic potential

of the entire cherry industry.

See also: Preservatives: Classifications and Properties

Further Reading

Brettin TS, Karle R, Crowe EL and Iezzoni AF (2000)

Chloroplast inheritance and DNA variation in

sweet, sour, and ground cherry. Journal of Heredity 91:

75–79.

Brown SK, Iezzoni AF and Fogle HW (1996) Cherries. In:

Janick J and Moore JN (eds) Fruit Breeding, Vol. I:

Tree and Tropical Fruits, pp. 213–255. New York:

John Wiley.

Iezzoni A, Schmidt H and Albertini A (1990) Cherries

(Prunus spp.). Acta Horticultura.

Perry R (1987) Cherry rootstocks. In: Rom RC and Carlson

RF (eds) Rootstocks for Fruit Crops, pp. 217–264. New

York: Wiley Interscience.

Webster AD and Looney NE (eds) (1996) Cherries: Crop

Physiology, Production and Uses, p. 464. New York:

Oxford University Press.

Westwood MN (1978) Temperate Zone Pomology, p. 428.

San Francisco, CA: W.H. Freeman and Co.

CHESTNUTS

N A M Saleh, National Research Centre, Cairo, Egypt

Global Distribution

0001 Castanea is a genus of about 12 species native to the

north temperature regions, belonging to the family

Fagaceae with close botanical relationship to birch.

The sweet chestnut (Castanea sativa Mill. synonyms:

C. vulgaris Lam., C. vesca Gaertn., and C. castanea

Karst.) is native from southern Europe, north Africa,

and Asia Minor to China. The main center of origin

of chestnut is thought to be located in the Ponto-

Caucasian region. It is cultivated in many parts of

the Himalayas, especially in Punjab and the Khasia

Hills. Naturalized in central, western, and northern

Europe, and introduced on the Pacific Coast of the

USA, Australia, and New Zealand, it is commonly

known as European, Spanish, Italian, Eurasian, or

sweet chestnut.

Description

0002Chestnut is a deciduous tree, which reaches heights

of up to 30 m. The shiny leaves, of about 20 cm in

length, are the most characteristic part of the tree.

They are lanceolate, with serrated margins, and have

15–20 pairs of straight, parallel veins. The female

flowers are green and rounded, growing at the base

of male catkins or in separate round catkins. The

male flowers are long, slender, creamy-white and

grow upright in catkins. The flowers appear in June

to early July. Fruits are in groups of one to three

single-seeded nuts, often 2–3.5 cm in diameter. Shiny

brown, with paler bases, they are thickly pubescent at

the tip, bearing a short-stalked perigynium with its

1140 CHESTNUTS

persistent styles. The seed has a large embryo but no

endosperm. Nuts of the European chestnut are gener-

ally dark brown in color and often lightly striped. The

nuts contain an edible kernel, enclosed in a thin,

tough, and astringent skin (pellicle) and surrounded

by a spinous, cup-like organ termed a cupule. The

latter is a unique feature of the family. The kernel of

European chestnut is often deeply grooved, with the

fibrous pellicle folded into the grooves, making it

difficult to separate this bitter covering from the

kernel. There are several cultivars of chestnut,

differing in the quality of kernels; the forms grown

in India, for example, are inferior to those cultivated

in Europe.

Cultivars

0003 In the past, only two cultivars were known: Asplenii-

folia with narrow leaves, often linear and irregularly

lobed, and Macrocarpa with large fruit. Later,

the following examples were cultivated: Marron

Combale, Marron Noursillard and Marron Quercy,

which originated in France. All have very large, light-

to dark-brown nuts and are very productive. Numbo

and Paragon are the most frequently grown cultivars

in the USA: they have medium-large, roundish nuts of

fair quality, and bear regularly. Ridgely, which origin-

ated in Dover, Delaware, has fair-sized nuts, of very

good quality and flavor, with two to three nuts per

bur; it is vigorous and productive. Rochester and

Comfort are grown to a limited extent. A number of

factors are involved in choosing a given cultivar: (1)

resistance to chestnut blight (caused by Cryphonectria

parasitica Murr.); (2) size of fruit, as large-sized nuts

are more profitable to sell; and (3) the ease with which

the ‘skin’ or pellicle can be removed from the kernel.

Commercial and Industrial Importance

Uses

0004 Chestnuts are grown as ornamentals and for the

edible nuts. Trees often bear nuts 2 or 3 years after

plantation. Propagation is by budding or grafting on

chestnut stocks. They are naturally tolerant of acid

soils and present no special cultural difficulties on

well-drained land. The chestnut blight may be injuri-

ous or fatal to susceptible species, and weevils may be

troublesome.

0005 The Fagaceae family is the source of some of the

most important hardwood timbers of the world,

the most notable being oak, beech, and chestnut. The

timber of the sweet chestnut is almost equal to oak in

strength and durability, and the one is often substi-

tuted for the other. Coppiced chestnut is in great

demand for fencing, which lasts for very many

years, even when not treated with creosote. The rela-

tively hard, durable, fine-grained wood is easy to split

but not easy to bend (density, 593–865 kg m

3

). It is

used for general carpentry, railway ties, and the

manufacture of cellulose. The bark and wood are

used for tanning. Wood and burs may be used for

firewood or for the production of charcoal.

0006European chestnuts are grown for the kernels of

the nuts, and are extensively eaten by humans and

animals. The nuts are used as a vegetable, boiled,

roasted, steamed, pure

ed, or in a dressing (stuffing)

for poultry and meats. In some European mountain-

ous regions, chestnuts replace wheat and potatoes in

the form of chestnut flour bread, and mashed chest-

nuts. Flour made of ground chestnuts is said to have

provided a staple ration for the Roman legions. In

Italy, chestnuts are prepared like a stew with gravy.

Dried nuts are used for cooking purposes in the same

way as the fresh nuts, or eaten like peanuts. They are

also used in brandy, in confectionery, in desserts, as a

coffee substitute, for thickening soups, and as a

source of oil. The largest nuts, called marron, com-

mand the highest price and are used to make the

famous French delicacy, marrons glace

s. Culled chest-

nuts are safely used for fattening poultry and hogs, as

well as for feeding cattle.

Yields

0007Chestnut trees begin to produce at an early age, and

can produce two tons or more of fresh nuts per

hectare. Yields average from 45 to 136 kg of nuts

per tree. In 60–80-year-old stands in Russia, yields

average 770 kg ha

1

and up to 1230 kg ha

1

in better

stands. Italy reports c. 1100 kg ha

1

, France c. 1500–

2200 kg ha

1

, and Spain c. 2800 kg ha

1

. In the best

years, 5000 kg ha

1

are reported. Nuts are marketed

to a limited degree, but are mostly locally cultivated

and used.

Biological Properties

0008The Greek physician Dioscorides noted the Castanea

sativa as a tree was a fruitful source of medicinal

remedies. The leaves, twigs, bark, flowering catkins,

and spiny cases of the nuts are good astringents, which

cause mucous membranes and skin to contract. They

were therefore used to control bleeding, aid in healing

wounds, and against diarrhea. The leaves, which con-

tain demulcents, were used in teas to soothe irritated

throats and in relieving symptoms of coughs and colds.

The nuts are also reported in folk remedies for the

treatment of fever, hematochezia, infections, sores,

inflammation, wounds, sclerosis, kidney ailments,

myalgia, nausea, and stomach ailments.

CHESTNUTS 1141

0009 Sweet chestnut (C. sativa) is related to the beech

family (Fagales) with close botanical relationship to

birch, which is known as a major pollen allergen in

Europe. It is not surprising that Castanea pollen can

cause allergies – particularly in areas where Castanea

trees are frequently found. Southern Switzerland

(Lugano) is reported to experience the highest Casta-

nea pollen loads and hence high Castanea allergy

rates. It is reported that patients allergic to pollen

are affected by oral allergy syndrome (allergy to

food resulting from contact between food and the

oral mucosa). A reported case of oral allergy syn-

drome to chestnut appears to be a manifestation of

immediate immunoglobulin E-dependent hypersensi-

tivity. It was also reported in a second study that a

patient with latex allergy has a high risk of contact

urticaria or even anaphylaxis to the related fruits such

as chestnut. Class I chitinases are relevant allergens of

avocado and chestnut, and could be the panallergens

responsible for the latex-fruit syndrome.

Chemistry

General

0010 C. sativa leaves proved to contain two flavonoid

aglycones (quercetin and myricetin) along with their

glycoides. A study of Castanea species indicated that

catechol tannins were more abundant in buds at the

tip and base, while bud scales contained about 80%

of the tannis of the whole bud. The leaves, bark, and

wood also contain tannins. High concentrations of

ellagic acid were found to be present in the hard-

wood of European chestnut (89 mg g

1

wood) as

compared to those of a number of red and white

oaks (19–63 mg g

1

wood). After mimosa and que-

bracho extracts, chestnut extract is the third most

important vegetable tannin used for leather produc-

tion. It is only the wood (8–13% tannins), however,

that is used in the tanning industry and for commer-

cial preparation of the chestnut extract. The chestnut

bark contains a number of polyphenols based on

ellagitannins, galloylesters, phenolic glycosides, and

hamamelitannins. Countries manufacturing the ex-

tract are France, Italy, and the USA. Commercial

liquid extracts contain 29–49% tannin, while solid

extracts contain 56–76% tannin.

0011 Chestnut seeds are desiccation-sensitive and have

high moisture contents in the mature stage. For this

reason, they are possibly better targets for pathogenic

fungi than nonrecalcitrant seeds, which might explain

in turn why chitinases are abundant and stable

proteins in chestnut cotyledons. A study of class Ib

endochitinase from C. sativa cotyledons showed

in vitro antifungal properties when assayed against

Trichoderma viride. (See Tannins and Polyphenols.)

Nutritional Composition

0012Recent reports of the US Department of Agriculture

for nutritional composition of unpeeled and roasted

chestnut seeds are outlined in Table 1. The chemical

composition is similar to that of wheat, and the starch

is easily digested after cooking. Spanish chestnuts are

reported to contain 2.87–3.03% ash, 9.61–10.96%

total protein, 2.55–2.84% fiber, 73.75–77.70% total

nitrogen free extract, and 7.11–9.58% fat. Chestnuts

from 19 natural stands in southern Yugoslavia

showed a total fat content of 4–5%; oleic and linoleic

acids predominated, followed by palmitic acid. (See

Wheat.)

Handling and Storage

Harvesting

0013The nuts fall to the ground within about a week after

they have become ripe in the hulls. Once fallen, they

are subject to depredation by birds, squirrels, and

mold. Traditionally, mature chestnuts have been

gathered from the ground after they fall. Some culti-

vars stick, and shaking or jarring the limbs is useful.

In other cultivars, burs open, and nuts fall to the

ground. Burs that fall and do not open can be made

to shed their nuts by pressure of the feet, or by

striking with a small wooden mallet. Some harvesters

use heavy leather gloves and twist nuts out of burs by

hand.

0014Unopened burs stored in a humid, cool 12–18



location will continue to mature and open in a week.

In gathering nuts, the collector usually has two pails

or containers, one for first-grade, perfect nuts, the

other for culls. Some sort of harvest mechanization

is essential for the development of a chestnut orchard

industry.

Storing

0015Fresh chestnuts contain 40–50% carbohydrate,

mostly in the form of starch, about 5% oil, 5% pro-

tein, and 40% moisture. They are highly perishable

because they lose water rapidly at normal room tem-

perature and humidity, causing the kernel to become

hard and incapable of germinating. Numerous fungi

and bacteria attack the nuts, causing decay and spoil-

age. High temperatures, as a result of remaining in the

sun, cause rapid kernel deterioration. The nuts should

be stored at 0–4



C under conditions of high humidity

but no free moisture. (See Storage Stability: Mechan-

isms of Degradation.)

1142 CHESTNUTS

0016Nuts should be picked up every morning and stored

in sacks, if they are to be shipped at once. If they are

to be kept for a while, they should be piled on the

floor to sweat. The pile should be stirred twice a day

for 2 days; then the nuts should be sacked. Nuts

should always be stored in a manner so that air can

circulate freely. A practical method for storing small

quantities of nuts is to mix the freshly harvested nuts

with dry peat moss in plastic bags, close the bags, and

refrigerate. Properly stored, they will keep satisfactor-

ily for 6 months and have been kept for as long as 3

years.

0017Nuts to be eaten raw should be ‘cured’ for several

days by allowing the kernel to dry to a spongy

texture. The amount of free sugar and sweetness is

maximized in this way.

Seed Propagation

0018Chestnut seeds require a moist cold treatment of

at least 1–2 months at 0–4



C to insure good and

uniform germination. Stored nuts should not be

subjected to temperatures much below freezing

(irreversible damage begins to occur around 4



or above 7



See also: Storage Stability: Mechanisms of Degradation;

Tannins and Polyphenols; Wheat: Grain Structure of

Wheat and Wheat-based Products