From the book
Fruits of Warm Climates
by Julia F. Morton
Carob
Ceratonia siliqua
FABACEAE
Non-fleshy
and bean-like, the carob would not be generally regarded as a fruit, in
the food-use sense, except for its sweetness. To many people it is
familiar only by name as "St. John's Bread", in allusion to the
"locusts" which, according to the Bible, sustained St. John the Baptist
in the desert, and the "husks" which tempted the hungry Prodigal Son,
though "no man gave unto him." The word "locust" was originally applied
to the carob tree; later to migratory and other grasshoppers; and the
name is attached to a number of other leguminous trees with pinnate
leaves and oblong pods (Gleditsia, Hymenaea, Parkia, Robinia). The carob tree is called carrubo in Sicily, carrubio in Italy, algarrobo in Guatemala, alfarrobeira in Brazil.
Description
The tree reaches 50 to 55 ft (15-17 m) in height and at an age of 18
years may have a trunk 33 in (85 cm) in circumference. The evergreen
leaves are pinnate with 6 to 10 opposite leaflets, oval, rounded at the
apex, dark-green, leathery, 1 to 2 1/2 in (2.5-6.25 cm) long. The tiny
red flowers are in short, slender racernes borne in clusters along the
branches–male, female or hermaphrodite on separate trees. The pod is
light- to dark-brown, oblong, flattened, straight or slightly curved,
with a thickened margin; 4 to 12 in (10-30 cm) long, 3/4 to 1 in (1-2.5
cm) wide, glossy, tough and fibrous. It is filled with soft,
semi-translucent, pale-brown pulp, scant or plentiful, and 10 to 13
flattened, very hard seeds which are loose in their cells and rattle
when the pod is fully ripe and dry. The unripe pod is green, moist and
very astringent; the ripe pod sweet when chewed (avoiding the seeds)
but the odor of the broken pod is faintly like Limburger cheese because
of its 1.3% isobutyric acid content.
Fig. 34: A rarity in southern Florida, this carob tree
on the campus of the University of Miami was 15
years old when photographed in 1954. It is still
bearing small fruits every year without cross-
pollination.
Origin and
Distribution
Alphonse
de Candolle said that the carob "grew wild in the Levant, probably on
the southern coast of Anatolia and in Syria, perhaps also in Cyrenaica.
Its cultivation began within historic time. The Greeks diffused it in
Greece and Italy, but it was afterwards more highly esteemed by the
Arabs, who propagated it as far as Morocco and Spain. In all these
countries the tree has become naturalized here and there in a less
productive form . . . ".
In Spain and Portugal it survives only
on their Atlantic coasts. Throughout the Mediterranean region, it is
grown only in the warmest areas near the coast, and the neighboring
islands–Cyprus, Crete, Sicily, Sardinia and Majorca. Producers in the
Bari region of Italy on the Adriatic coast have long exported the pods
to Russia and central Europe. Prince Belmonte in the Province of
Salerno, Italy, was a leading influence in the 19th century in the use
of the carob as an ornamental and avenue tree and in the planting of
thousands for reforestation of the slopes of the Appenines.
Spanish
missionaries introduced the carob into Mexico and southern California.
In 1856, 8,000 seedlings, from seed brought in from Spain by the United
States Patent Office, were distributed in the southern states. More
seeds came from Israel in 1859. Many carobs were planted in Texas,
Arizona, California and a few in Florida as ornamental and street
trees. Seeds privately imported from Dalmatia were planted in
California in 1873.
In the Mediterranean region, peasants have
virtually lived on the pods in times of famine, but the tree is valued
mostly as providing great amounts of pods as feed for livestock, as it
is also in the State of Campinas, Brazil. Imported pods used to be
regularly sold by street vendors in the Italian section of lower New
York City for chewing. In the early 1920's, there was much promotion of
carob culture in California, especially allied with the development of
arid lands, and there was a flurry of activity in producing "health
food" products from imported pods. Some of these products are still
sold today, especially as substitutes for chocolate. Dr. J. Eliot Coit,
of Vista, California, led in the study of the carob and wrote
extensively on its potential improvement as a crop and its utilization.
In
1949, Dr. Walter Rittenhouse provided funds for the establishment of a
30-year test plot in northern San Diego County, where 400 local nursery
seedlings and many trees grafted with Mediterranean budwood were
planted and evaluated. Fruits from several thousand ornamental carob
trees in California and Arizona were collected in an effort to identify
superior types for human food use. Budwood of the most promising clones
was supplied to horticulturists in Tunisia, Israel, Australia, South
Africa, Hawaii, Mexico, Brazil and Chile.
Varieties
From more than
80 clones, 7 selections made by Coit were set out at the Citrus
Research Center of the University of California for preservation. The 7
are, briefly:
'Amele'-an
old commercial variety from Italy; S.P.I. #19437. Female. Pods
light-brown, straight or slightly curved, 5 1/2 to 6 1/4 in (14-16 cm)
long, 3/4 to 1 in (2-2.5 cm) wide; 53.8% sugar content under irrigation
near Indio. Flavor good. Season: September at Indio; October at Vista.
'Casuda'-a
very old cultivar from Spain. Female. Pod brown, mostly straight; 4 3/4
in (12 cm) long; 3/5 in (1.5 cm) wide; 51.7 % sugar at Vista; 56.7 %
under irrigation at Indio. Flavor fair. Season: September at Indio;
October at Vista.
'Clifford'-seedling
street tree in Riverside. Hermaphrodite. Pod light-brown, slightly
curved, 5 1/8 in (13 cm) long, 3/4 in (2 cm) wide; 52.9% sugar content.
Flavor fair. Season: early October; bears regularly and heavily.
'Sfax'-from
Menzel bou Zelfa, Tunisia; S.P.I. #187063. Female. Pod red-brown,
straight or slightly curved; 6 in (15 cm) long, 3/4 in (2 cm) wide;
56.6% sugar at Vista, 45.6% at Indio. Excellent flavor. Season: August
at Indio, September at Vista. A regular, medium-heavy bearer.
'Santa Fe'-seedling
from Santa Fe Springs, California. Hermaphrodite; self-fertile. Pod
light-brown, slightly curved, often twisted; 7 to 7 7/8 in (18-20 cm)
long, 3/4 in (2 cm) wide; 47.5% sugar at Vista. Excellent flavor.
Season: October. Bears regular, good crops. Good for coastal foothills.
Not suited to irrigated culture at Indio.
'Tantillo'-from
Sicily; S.P.I. #233580. Hermaphrodite. Pod dark-brown, mostly straight;
5 1/8 to 6 in (13-15 cm) long, 3/4 in (2 cm) wide. Of fair flavor.
Season: mid-September to mid-October. Bears heavily and regularly.
'Tylliria'-from
Cyprus; their chief export variety; S.P.I. # 189008. Female. Pod dark
mahogany-brown, slightly curved, 6 in (15 cm) long, 3/4 to 1 in (2-2.5
cm) wide; 47.4% sugar at Vista; 50.9% at Indio; 48.8% in Cyprus. Good
flavor. Season: mid-August to mid-September at Indio; October at Vista.
Adapted
to coastal foothills. (As reported from Cyprus, seed content is 7.6 to
10.6%; pod contains 51 % sugar and the seeds 49% gum).
These 7 superseded some older cultivars, including 'Bolser', 'Conejo', 'Gabriel', 'Horne', and 'Molino'; all hermaphroditic.
Other common cultivars in Cyprus are:
'Koundourka'-a
tree with weeping branches; mature pods generally less than 6 1/2 in
(17 cm) long; they split readily; have 14.7% seeds with a high (58%)
gum content.
'Koumbota'-a large-growing tree with "knotty" pods with low seed content. Pods contain 53% sugar; seeds, 53% gum.
Grafted
types are classed as 'Imera'. The name 'Apostolika' is a general term
for seedlings of fair quality. Wild types as a group are called 'Agria'.
Pollination
In a planting of
female trees, one male should be included for every 25 or 30 females.
In southern Europe, branches from male trees are grafted onto some of
the females in an orchard instead of interplanting male trees.
Climate
The carob is slightly hardier than the sweet orange. Young trees suffer
frost damage. Mature tees can endure a temperature drop to 20º F
(-6.67º C). Frost during the blooming period will reduce or prevent
fruit-set. The tree does best in a Mediterranean-type climate with
cool, not cold, winters, mild to warm springs, and warm to hot summers
with little or no rain. Temperatures in carob-growing regions of Israel
may reach 104º to 122º F (40º-50º C) in summer. Ideal annual
precipitation is 30 in (75 cm), but widely spaced trees will thrive
with only 6 to 15 in (15-37.5 cm) without irrigation in mild climates.
The pods should not be exposed to rain or heavy dew after they have
turned brown and developed a high sugar content. Wet pods ferment
quickly.
Soil
The tree flourishes in
widely divergent soils, from rocky hillsides to deep sand or heavy
loam, but must have good drainage. In Nicosia, Cyprus, a large
plantation was developed by dynamiting planting holes in caprock
underlaid with limestone (pH 9). The carob is not tolerant of acid or
wet soils; it is extremely drought-tolerant.
Propagation
Fresh seeds germinate quickly and may be sown directly in the field.
Dried, hard seeds need to be scarified or chipped and then soaked in
water or dilute sulfuric or hydrochloric acid solutions until they
swell. In Cyprus, seeds are planted in sand and kept wet for 6 weeks or
more, periodically sifting out those that have swollen to 3 times
normal size. Germination rate may be only 25%. The swollen seeds are
traditionally planted in flats and when they produce the second set of
leaves they are transferred to small pots. When 12 in (30 cm) tall,
they are transplanted to large containers or nursery rows. A recently
developed technique is to plant the seeds in 2 halves of clay
drainpipes bound together or in plastic tubes packed in deep wooden
boxes to accommodate the long taproot. In perhaps a year, the tubes are
split and the seedlings are planted in the field in holes made with a
post-hole digger. Budding is done when the stem is at least 3/8 in (1
cm) thick.
The
shield-budding system is employed, or sometimes a blend of budding and
grafting, in February and March in Cyprus, in April, May and June in
California and Mexico. Male trees or those that bear poorly are
top-worked to productive cultivars.
Culture
The carob grows slowly during the first year. Stem-elongation in young
plants has been expedited by application of gibberellin (50 mg/liter
monthly, or 25 mg/liter semi-monthly) for 5 months. It is necessary to
cut back the taproot 6 months before transferring to the field if the
plant is not grown by the tube/post-hole method. Large trees cannot be
successfully transplanted.
A
good spacing is 30 ft (9 m) apart each way. Most carob growers consider
fertilizing unnecessary but the government of Cyprus subsidizes
fertilization–so much per tree. Irrigation must be provided in very dry
seasons if the tree is grown for its fruits. Budded trees begin to bear
in the 6th year from planting. A carob tree may remain productive for
80 to 100 years.
Harvesting
The pods must be harvested before winter rains. They are shaken down by
means of a long pole with a terminal hook to grasp the branches. Those
that don't fall readily are knocked off with the pole. The pods are
caught on canvas sheets laid on the ground. Then they are sun-dried for
1 or 2 days until the moisture content is reduced to 8% or below and
then go through a kibbling process–crushing and grading into 4
categories: cubed, medium-kibbled, meal, and seed kernels.
Yield
At 6 years of age, a budded tree in California should yield about 5 lbs
(2.25 kg). At 12 years, the crop should be 100 lbs (45 kg).
Productivity increases steadily up to 25 or 30 years when the yield may
average 200 lbs (90 kg). In Israel individual trees have produced 450
to 550 lbs (204-227 kg) 18 years after grafting. Some ancient trees in
the Mediterranean area are reported to have borne 3,000 lbs (1,360 kg)
in a season.
Pests and
Diseases
In the Mediterranean area, the major pest is the carob moth, Myelois ceratoniae. It lays eggs on the flowers or newly-formed pods and the larvae bore into the pods and ruin them. The larvae of a midge, Asphondylia gennadii, cause stunting of the pods. Some of the best cultivars are resistant to these pests.
In Cyprus, the tree is subject to several scale insects: Aspidiotus ceratoniae, Lecanium sp., Lepidosaphes sp. and the red scale, Aonidiella aurantii.
A beetle, Cerambyx velutinus, may bore holes in the trunk. Rats climb
the trees, hide among the branches, gnaw the bark until the branches
die. Such branches are pruned out twice a year. The only pests reported
as attacking carob trees in California are scale insects, including the
red scale. Ground squirrels feed on plants under 2 years of age. Pocket
gophers are very fond of carob roots, and rabbits and deer graze on the
young trees.
Diseases are few. In Cyprus, deformation of young pods may be caused by the fungus Oidium ceratoniae. Cercospora ceratoniae occasionally induces leaf-spotting.
Plate XV: CAROB, Ceratonia siliqua
Food Uses
Apart from being chewed as a sweetmeat, carob pods are processed to a
cocoa -like flour which is added to cold or heated milk for drinking.
It has been combined with wheat flour in making bread or pancakes. A
flour made by beating the seeded pods is high in fiber and has been
utilized in breakfast foods. The finer flour is also made into
confections, especially candy bars. The pods, coarsely ground and
boiled in water yield a thick, honey-like sirup, or molasses.
The
seeds constitute 10 to 20% of the pod. They yield a tragacanth-like gum
(manogalactan), called in the trade "Tragasol", which is an important
commercial stabilizer and thickener in bakery goods, ice cream, salad
dressings, sauces, cheese, salami, bologna, canned meats and fish,
jelly, mustard, and other food products. The seed residue after gum
extraction can be made into a starch- and sugar-free flour of 60%
protein content for diabetics.
In Germany, the roasted seeds have served as a substitute for coffee. In Spain, they have been mixed with coffee.
It
has been demonstrated that the extracted sugars of the pod (sucrose,
glucose, fructose and maltose in the ratio 5:1:1:0:7) can be utilized
to produce fungal protein. Infusions of the pulp are fermented into
alcoholic beverages.
Food Value
| Food
Value Per
100 g of Edible Portion* |
| Calories
|
180 |
| Moisture
|
11.2 g |
| Protein |
4.5 g |
| Fat |
1.4 g |
| Carbohydrates* |
80.7 g |
| Fiber |
7.7 g |
| Ash |
2.2 g |
| Calcium |
352 mg |
| Phosphorus |
81 mg |
| *Sugar content may be as high as 72%. |
|
The pods contain up to 1.5% tannins which interfere with the body's utilization of protein.
Other Uses
Pods: The pods are relished
by horses, cattle, pigs, goats and rabbits. Whole pods are broken up in
a hammermill in order to crush the seeds as well. Because of the tannin
content, carob pods should constitute no more than 10% of total feed,
other-wise they will depress growth rate. They cannot be fed to
chickens. The flour is often utilized in dog biscuits. Great quantities
of pods have been imported into the United States for flavoring uncured
tobacco.
Seeds: The seed gum
is much employed in the manufacture of cosmetics, pharmaceutical
products, detergents, paint, ink, shoe polish, adhesives, sizing for
textiles, photographic paper, insecticides and match heads. It is also
utilized in tanning. Where rubber latex is produced, the gum is added
to cause the solids to rise to the surface. It is also used for bonding
paper pulp and thickening silkscreen pastes, and some derivatives are
added to drilling mud. It has many other actual or potential
applications. A flour made from the seeds serves as cattle feed.
Wood:
The heartwood is hard and close-grained. It is prized for turnery and
cabinetwork. As a fuel it burns slowly and makes excellent charcoal. It
yields algarrobin, which gives textiles a light-brown hue.
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