From the book
Fruits of Warm Climates
by Julia F. Morton
Pomegranate
Punica granatum L.
PUNICACEAE
Steeped in history and romance and almost in a class by itself, the pomegranate, Punica granatum L., belongs to the family Punicaceae which includes only one genus and two species, the other one, little-known, being P. protopunica Balf. peculiar to the island of Socotra.
Plate XLIX: POMEGRANATE, Punica granatum
Despite
its ancient background, the pomegranate has acquired only a relatively
few commonly recognized vernacular names apart from its many regional
epithets in India, most of which are variations on the Sanskrit dadima
or dalim, and the Persian dulim or dulima. By the French it is called
grenade; by the Spanish, granada (the fruit), granado (the plant); by
the Dutch, granaatappel, and Germans, granatapfel; by the Italians,
melogranato, melograno granato, pomo granato, or pomo punico. In
Indonesia, it is gangsalan; in Thailand, tab tim; and in Malaya,
delima. Brazilians know it as roma, romeira or romazeira. The Quecchi
Indian name in Guatemala is granad. The Samoan name is limoni. The
generic term, Punica, was the Roman name for Carthage from whence the
best pomegranates came to Italy.
Description
An
attractive shrub or small tree, to 20 or 30 ft (6 or 10 m) high, the
pomegranate is much-branched, more or less spiny, and extremely
long-lived, some specimens at Versailles known to have survived two
centuries. It has a strong tendency to sucker from the base. The leaves
are evergreen or deciduous, opposite or in whorls of 5 or 6,
short-stemmed, oblong-lanceolate, 3/8 to 4 in (1-10 cm) long, leathery.
Showy flowers are home on the branch tips singly or as many as 5 in a
cluster. They are 1 1/4 in (3 cm) wide and characterized by the thick,
tubular, red calyx having 5 to 8 fleshy, pointed sepals forming a vase
from which emerge the 3 to 7 crinkled, red, white or variegated petals
enclosing the numerous stamens. Nearly round, but crowned at the base
by the prominent calyx, the fruit, 2 1/2 to 5 in (6.25-12.5 cm) wide,
has a tough, leathery skin or rind, basically yellow more or less
overlaid with light or deep pink or rich red. The interior is separated
by membranous walls and white spongy tissue (rag) into compartments
packed with transparent sacs filled with tart, flavorful, fleshy,
juicy, red, pink or whitish pulp (technically the aril). In each sac,
there is one white or red, angular, soft or hard seed. The seeds
represent about 52% of the weight of the whole fruit.
Origin and Distribution
The
pomegranate tree is native from Iran to the Himalayas in northern India
and has been cultivated since ancient times throughout the
Mediterranean region of Asia, Africa and Europe. The fruit was used in
many ways as it is today and was featured in Egyptian mythology and
art, praised in the Old Testament of the Bible and in the Babylonian
Talmud, and it was carried by desert caravans for the sake of its
thirst-quenching juice. It traveled to central and southern India from
Iran about the first century A.D. and was reported growing in Indonesia
in 1416. It has been widely cultivated throughout India and drier parts
of southeast Asia, Malaya, the East Indies and tropical Africa. The
most important growing regions are Egypt, China, Afghanistan, Pakistan,
Bangladesh, Iran, Iraq, India, Burma and Saudi Arabia. There are some
commercial orchards in Israel on the coastal plain and in the Jordan
Valley.
It is rather commonly planted and has become naturalized
in Bermuda where it was first recorded in 1621, but only occasionally
seen in the Bahamas, West Indies and warm areas of South and Central
America. Many people grow it at cool altitudes in the interior of
Honduras. In Mexico it is frequently planted, and it is sometimes found
in gardens in Hawaii. The tree was introduced in California by Spanish
settlers in 1769. It is grown for its fruit mostly in the dry zones of
that state and Arizona. In California, commercial pomegranate
cultivation is concentrated in Tulare, Fresno and Kern counties, with
small plantings in Imperial and Riverside counties. There were 2,000
acres (810 ha) of bearing trees in these areas in the 1920's.
Production declined from lack of demand in the 1930's but new plantings
were made when demand increased in the 1960's.
Cultivars
There
is little information available on the types grown in the Near East,
except that the cultivars 'Ahmar', 'Aswad', 'Halwa' are important in
Iraq, and 'Mangulati' in Saudi Arabia. 'Wonderful' and 'Red Loufani'
are often grown in the Jewish sector of Israel, while the sweeter, less
tangy 'Malissi' and 'Ras el Baghl', are favored in the Arab sector.
In
India there are several named cultivars. Preference is usually given
those with fleshy, juicy pulp around the seeds. Types with relatively
soft seeds are often classed as "seedless". Among the best are 'Bedana'
and 'Kandhari'. 'Bedana' is medium to large, with brownish or whitish
rind, pulp pinkish-white, sweet, seeds soft. 'Kandhari' is large,
deep-red, with deep-pink or blood-red, subacid pulp and hard seeds.
Others include:
'Alandi' ('Vadki')–medium-sized, with fleshy red or pink, subacid pulp, very hard seeds.
'Dholka'–large,
yellow-red, with patches of dark-pink and purple at base, or all-over
greenish-white; thick rind, fleshy, purplish-white or white, sweet,
pulp; hard seeds. The plant is evergreen, non-suckering, desirable for
commercial purposes in Delhi.
'Kabul'–large, with dark-red and pale-yellow rind; fleshy, dark-red, sweet, slightly bitter pulp.
'Muscat
Red'–small to medium, with thin or fairly thick rind, fleshy,
juicy, medium-sweet pulp, soft or medium-hard seeds. The plant is a
moderately prolific bearer.
'Paper Shell'–round, medium to
large, pale-yellow blushed with pink; with very thin rind, fleshy,
reddish or pink, sweet, very juicy pulp and soft seeds. Bears heavily.
'Poona'–large, with dark-red, gray or grayish-green rind, sometimes spotted, and orange-red or pink-and-red pulp.
'Spanish
Ruby'–round, small to medium or large; bright-red, with thin
rind, fleshy, rose-colored, sweet, aromatic pulp, and small to medium,
fairly soft seeds. Considered medium in quality.
'Vellodu'–medium to large, with medium-thick rind, fleshy, juicy pulp and medium-hard seeds.
'Muscat
White'–large, creamy-white tinged with pink; thin rind; fleshy,
cream-colored, sweet pulp; seeds medium-hard. Bears well. Desirable for
commercial planting in Delhi.
'Wonderful'–originated as a
cutting in Florida and propagated in California in 1896. The fruit is
oblate, very large, dark purple-red, with medium-thick rind; deep-red,
juicy, winey pulp; medium-hard seeds. Plant is vigorous and productive.
In
California, 'Spanish Ruby' and 'Sweet Fruited' were the leading
cultivars in the past century, but were superseded by 'Wonderful'. In
recent years 'Wonderful' is losing ground to the more colorful
'Grenada'.
Mexicans take especial pride in the pomegranates of
Tehuacan, Puebla. Many cultivars are grown, including 'Granada de
China' and 'Granada Agria'.
The Japanese dwarf pomegranate, P. granatum var. nana,
is especially hardy and widely grown as an ornamental in pots. The
flowers are scarlet, the fruit only 2 in (5 cm) wide but borne
abundantly. Among other ornamental cultivars are 'Multiplex' with
double, creamy white blooms; 'Chico', double, orange-red; 'Pleniflora',
double, red; 'Rubra Plena', double, red; 'Mme. Legrelle' and
'Variegata', double, scarlet bordered and streaked with yellowish-white.
Pollination
The
pomegranate is both self-pollinated and cross-pollinated by insects.
There is very little wind dispersal of pollen. Self-pollination of
bagged flowers has resulted in 45% fruit set. Cross-pollination has
increased yield to 68%. In hermaphrodite flowers, 6 to 20% of the
pollen may be infertile; in male, 14 to 28%. The size and fertility of
the pollen vary with the cultivar and season.
Climate
The
species is primarily mild-temperate to subtropical and naturally
adapted to regions with cool winters and hot summers, but certain types
are grown in home dooryards in tropical areas, such as various islands
of the Bahamas and West Indies. In southern Florida, fruit development
is enhanced after a cold winter. Elsewhere in the United States, the
pomegranate can be grown outdoors as far north as Washington County,
Utah, and Washington, D.C., though it doesn't fruit in the latter
locations. It can be severely injured by temperatures below 12° F
(-11.11° C). The plant favors a semi-arid climate and is extremely
drought -tolerant.
Soil
The
pomegranate thrives on calcareous, alkaline soil and on deep, acidic
loam and a wide range of soils in between these extremes. In northern
India, it is spontaneous on rockstrewn gravel.
Propagation
Pomegranate
seeds germinate readily even when merely thrown onto the surface of
loose soil and the seedlings spring up with vigor. However, to avoid
seedling variation, selected cultivars are usually reproduced by means
of hardwood cuttings 10 to 20 in (25-50 cm) long. Treatment with 50
ppm. indole-butyric acid and planting at a moisture level of 15.95%
greatly enhances root development and survival. The cuttings are set in
beds with 1 or 2 buds above the soil for 1 year, and then transplanted
to the field. Grafting has never been successful but branches may be
air-layered and suckers from a parent plant can be taken up and
transplanted.
Culture
Rooted
cuttings or seedlings are set out in pre-fertilized pits 2 ft (60 cm)
deep and wide and are spaced 12 to 18 ft (3.5-5.5 m) apart, depending
on the fertility of the soil. Initially, the plants are cut back to 24
to 30 in (60-75 cm) in height and after they branch out the lower
branches are pruned to provide a clear main stem. Inasmuch as fruits
are borne only at the tips of new growth, it is recommended that, for
the first 3 years, the branches be judiciously shortened annually to
encourage the maximum number of new shoots on all sides, prevent
straggly development, and achieve a strong, well-framed plant. After
the 3rd year, only suckers and dead branches are removed.
For
good fruit production, the plant must be irrigated. In Israel, brackish
water is utilized with no adverse effect. In California, irrigation
water is supplied by overhead sprinklers which also provide frost
protection during cold spells. The pomegranate may begin to bear in 1
year after planting out, but 2 1/2 to 3 years is more common.
Harvesting and Yield
The
fruits ripen 6 to 7 months after flowering. In Israel, cultivar
'Wonderful' is deemed ready for harvest when the soluble solids (SSC)
reach 15%. In California, maturity has been equated with 1.8%
titratable acidity (TA) and SSC of 17% or more. The fruit cannot be
ripened off the tree even with ethylene treatment. Growers generally
consider the fruit ready for harvest if it makes a metallic sound when
tapped. The fruit must be picked before over maturity when it tends to
crack open if rained upon or under certain conditions of atmospheric
humidity, dehydration by winds, or insufficient irrigation. Of course,
one might assume that ultimate splitting is the natural means of seed
release and dispersal.
The fruits should not be pulled off but
clipped close to the base so as to leave no stem to cause damage in
handling and shipping. Appearance is important, especially in the
United States where pomegranates may be purchased primarily to enhance
table arrangements and other fall (harvest-time) decorations. Too much
sun exposure causes sunscald–brown, russeted blemishes and
roughening of the rind.
The fruit ships well, cushioned with
paper or straw, in wooden crates or, for nearby markets, in baskets.
Commercial California growers grade the fruits into 8 sizes, pack in
layers, unwrapped but topped with shredded plastic, in covered wood
boxes, precool rapidly, and ship in refrigerated trucks.
Keeping Quality and Storage
The
pomegranate is equal to the apple in having a long storage life. It is
best maintained at a temperature of 32° to 41° F
(0°-5° C). The fruits improve in storage, become juicier and
more flavorful; may be kept for a period of 7 months within this
temperature range and at 80 to 85% relative humidity, without shrinking
or spoiling. At 95% relative humidity, the fruit can be kept only 2
months at 41° F (5° C); for longer periods at 50° F
(10° C). After prolonged storage, internal breakdown is evidenced
by faded, streaky pulp of flat flavor. 'Wonderful' pomegranates, stored
in Israel for Christmas shipment to Europe, are subject to superficial
browning ("husk scald"). Control has been achieved by delaying harvest
and storing in 2% O2 at 35.6° F (2° C). Subsequent transfer
to 68º F (20° C) dispels off-flavor from ethanol accumulation.
Pests and Diseases
The pomegranate butterfly, Virachola isocrates,
lays eggs on flower-buds and the calyx of developing fruits; in a few
days the caterpillars enter the fruit by way of the calyx. These fruit
borers may cause loss of an entire crop unless the flowers are sprayed
2 times 30 days apart. A stem borer sometimes makes holes right through
the branches. Twig dieback may be caused by either Pleuroplaconema or Ceuthospora Phyllosticta. Discoloration of fruits and seeds results from infestation by Aspergillus castaneus. The fruits may be sometimes disfigured by Sphaceloma punicae. Dry rot from Phomopsis sp. or Zythia versoniana
may destroy as much as 80% of the crop unless these organisms are
controlled by appropriate spraying measures. Excessive rain during the
ripening season may induce soft rot. A post-harvest rot caused by Alternaria solani was observed in India in 1974. It is particularly prevalent in cracked fruits.
Minor problems are leaf and fruit spot caused by Cercospora, Gloeosporium and Pestalotia sp.; also foliar damage by whitefly, thrips, mealybugs and scale insects; and defoliation by Euproctis spp. and Archyophora dentula.
Termites may infest the trunk. In India, paper or plastic bags or other
covers may be put over the fruits to protect them from borers, birds,
bats and squirrels.
Food Uses
For
enjoying out-of-hand or at the table, the fruit is deeply scored
several times vertically and then broken apart; then the clusters of
juice sacs can be lifted out of the rind and eaten. Italians and other
pomegranate fanciers consider this not a laborious handicap but a
social, family or group activity, prolonging the pleasure of dining.
In
some countries, such as Iran, the juice is a very popular beverage.
Most simply, the juice sacs are removed from the fruit and put through
a basket press. Otherwise, the fruits are quartered and crushed, or the
whole fruits may be pressed and the juice strained out. In Iran, the
cut-open fruits may be stomped by a person wearing special shoes in a
clay tub and the juice runs through outlets into clay troughs.
Hydraulic extraction of juice should be at a pressure of less than 100
psi to avoid undue yield of tannin. The juice from crushed whole fruits
contains excess tannin from the rind (as much as .175%) and this is
precipitated out by a gelatin process. After filtering, the juice may
be preserved by adding sodium benzoate or it may be pasteurized for 30
minutes, allowed to settle for 2 days, then strained and bottled. For
beverage purposes, it is usually sweetened. Housewives in South
Carolina make pomegranate jelly by adding 7 1/2 cups of sugar and 1
bottle of liquid pectin for every 4 cups of juice. In Saudi Arabia, the
juice sacs may be frozen intact or the extracted juice may be
concentrated and frozen, for future use. Pomegranate juice is widely
made into grenadine for use in mixed drinks. In the Asiatic countries
it may be made into a thick sirup for use as a sauce. It is also often
converted into wine.
In the home kitchen, the juice can be easily extracted by reaming the halved fruits on an ordinary orange-juice squeezer.
In
northern India, a major use of the wild fruits is for the preparation
of "anardana"–the juice sacs being dried in the sun for 10 to 15
days and then sold as a spice.
| Food
Value Per
100 g of Edible Portion* |
| Calories | 63-78 | | Moisture | 72.6-86.4 g | | Protein | 0.05-1.6 g | | Fat | Trace only to 0.9 g | | Carbohydrates | 15.4-19.6 g | | Fiber | 3.4-5.0 g | | Ash | 0.36-0.73 g | | Calcium | 3-12 mg | | Phosphorus | 8-37 mg | | Iron | 0.3-1.2 mg | | Sodium | 3 mg | | Potassium | 259 mg | | Carotene | None to Trace | | Thiamine | 0.003 mg | | Riboflavin | 0.012-0.03 mg | | Niacin | 0.180-0.3 mg | | Ascorbic Acid | 4-4.2 mg | | Citric Acid | 0.46-3.6 mg | | Boric Acid | 0.005 mg |
*Analyses of fresh juice sacs made by various investigators. |
|
Toxicity
A
tannin content of no more than 0.25% in the edible portion is the
desideratum. Many studies have shown that tannin is carcinogenic and
excessive ingestion of tannin from one or more sources, over a
prolonged period, is detrimental to health. (See also "Medicinal Uses"
regarding overdoses of bark.)
Other Uses
All
parts of the tree have been utilized as sources of tannin for curing
leather. The trunk bark contains 10 to 25% tannin and was formerly
important in the production of Morocco leather. The root bark has a 28%
tannin content, the leaves, 11%, and the fruit rind as much as 26%. The
latter is a by-product of the "anardana" industry. Both the rind and
the flowers yield dyes for textiles. Ink can be made by steeping the
leaves in vinegar. In Japan, an insecticide is derived from the bark.
The pale-yellow wood is very hard and, while available only in small
dimensions, is used for walking-sticks and in woodcrafts.
Medicinal
Uses: The juice of wild pomegranates yields citric acid and sodium
citrate for pharmaceutical purposes. Pomegranate juice enters into
preparations for treating dyspepsia and is considered beneficial in
leprosy.
The bark of the stem and root contains several
alkaloids including isopelletierine which is active against tapeworms.
Either a decoction of the bark, which is very bitter, or the safer,
insoluble Pelletierine Tannate may be employed. Overdoses are emetic
and purgative, produce dilation of pupila, dimness of sight, muscular
weakness and paralysis.
Because of their tannin content,
extracts of the bark, leaves, immature fruit and fruit rind have been
given as astringents to halt diarrhea, dysentery and hemorrhages.
Dried, pulverized flower buds are employed as a remedy for bronchitis.
In Mexico, a decoction of the flowers is gargled to relieve oral and
throat inflammation. Leaves, seeds, roots and bark have displayed
hypotensive, antispasmodic and anthelmintic activity in bioassay.
|
|