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.
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 branchesmale, 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.
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 islandsCyprus, 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.
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'.
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.
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.
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.
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.
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 in) apart each way. Most carob growers consider fertilizing unnecessary but the government of Cyprus subsidizes fertilizationso 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.
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 processcrushing and grading into 4 categories: cubed, medium-kibbled, meal, and seed kernels.
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|
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 Per 100 g of Carob Flour
The pods contain up to 1.5% tannins which interfere with the body's utilization of protein.
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.