The carob (Ceratonia siliqua) is an evergreen tree or shrub of the family Leguminosae, also known as the legume, pea, or bean family. This large and agriculturally important family of flowering plants includes: Alfalfa, lentils, beans, chick-peas, peas, peanuts, soybeans, kudzu, sweet pea, milkvetch, black locust, clover, wild blue lupine, silvery lupine, Pacific lupine, sundial lupine, bluebonnets, locoweed, snap beans, wisteria, mesquite, broom, gorse, and the mimosa.
The original distribution of Ceratonia siliqua is not clear as it has been extensively cultivated for at least 4,000 years in most countries of the Middle East and the eastern Mediterranean region, usually in mild and dry places with poor soils. Some researchers believe it originated in the Mediterranean basin, and others debate that it could have originated in the Middle East, and because this food source could be stored and transported for long distances, it migrated westward at an early stage, via human trade. Nevertheless, although carobs occur in many places around the western Mediterranean, its value was recognized by the ancient Greeks, who brought it home to Greece from the Middle East and also distributed it to Italy. It was also most likely disseminated by the Arabs all along the North African coast and into the south and east of Spain, from where it migrated to the south of Portugal and the southeast of France.
In more recent times the carob was spread by Spaniards to other regions of the world with similar Mediterranean type climates, including, California, Arizona, Mexico, Chile and Argentina. Mediterranean emigrants took it to parts of Australia, and English settlers brought it with them to South Africa and India.
The carob is also known as “St. John’s bread” or “locust bean” because it is believed that it was the beans and flesh of carob pods which sustained John the Baptist during his long trek through the desert, and not real locusts at all. From that we get the names “Johannis Brotbaum” in German, and “Johannesbroodboom” in Afrikaans.
The magnificent carob tree grows as a sclerophyllous evergreen shrub or tree which can grow anything from 10 to 15m tall in its natural habitat. Sclerophyllous vegetation is characterized by hard, leathery, evergreen foliage that is specially adapted to prevent moisture loss. With maturity the tree develops a broad semi-spherical crown, and a thick trunk with rough brown bark and sturdy branches. The carob is classified as evergreen because it does not shed its leaves in autumn, however, about every second year around springtime it will partially drop leaves, replacing them immediately with fresh new ones.
Carob trees flower in late summer and early autumn and this cool season blooming allows the trees to concentrate on vegetative survival during the warmer spring and hot and dry summer months. Because they are self-pollinating, they do not rely on springtime pollinators for reproduction. The carob is commonly a dioecious species, therefore male and female flowers are borne on different trees. There are also hermaphroditic forms that can produce both male and female reproductive organs.
Female flowers consist of a pistil on a disk and rudimentary stamens, surrounded by 5 hairy sepals. The ovary is bent, consisting of two carpels containing several ovules. The stigma has 2 lobes. Male flowers consist of a nectary disk with 5 stamens with delicate filaments surrounded by hairy sepals. In the centre of the disk there is a rudimentary pistil. Hermaphrodite flowers are a combination of both types, containing a pistil and a complement of 5 stamens.
Although the flowers are small, their attractive, green-tinted, dark red blooms are spirally arranged in dense clusters which droop down in catkin-like racemes. Flowering occurs on spurs from old wood and even on the trunk. Flowers are produced in late summer and autumn and let off a musky smell to attract bees and flies.
The fruit is an elongated, compressed pod which can be flat, curved, or twisted, and about 10 to 30cm long, 1.5 to 3.5cm broad and about 1cm thick. When ripe they are leathery and brown with a wrinkled surface. The pulp comprises an outer leathery layer and a softer inner region, and the numerous smooth and glossy brown seeds are very hard.
Carob production in the world has declined dramatically over the past 50 years, largely due to low pod prices and home consumption, and commercial world production of carob pods is estimated around 310,000 tons, and is mainly concentrated in Spain, Italy, Portugal, Morocco, Greece, Cyprus, Turkey, and Algeria. There is some production in Croatia, Tunisia and Malta, and small amounts are also produced in Australia, California, and South Africa.
Generally, grafted cultivars produce larger fruits than unselected wild types, and today at least seven clones are used worldwide, ranging in flavour, pod size, seed production, as well as sugar content (from 48% to 56%). Research on the carob was conducted in the USA in 1949, with the best varieties selected and cloned, some of which were then supplied to South Africa.
Despite the huge potential of carob to be utilised as a protein-rich food crop in South Africa, it is not yet cultivated on a large commercial scale here, and although there are some orchards established in the Western Cape, carob is not a very profitable crop. Agricultural research done in South Africa concluded that the winter rainfall regions were the most suitable for commercial carob production. The main reason for this is that carob pods ripen in late summer, and too much rainfall at this time results in the pods rotting away.
No processing of carob pods is done in South Africa, and all our carob powder is imported. Also, no carob related products are included in the feeding rations of animals, but farmers do allow animals to eat the sugar-rich pods. For optimal animal digestion, pods and hard seeds should be chopped in a hammer-mill.
Carob Mill Museum - Image by Dimitris Vetsikas from PixabayThe many uses of Carob:
In days gone by jewellers used the uniform weight of the seeds of the carob tree (200mg) to measure the weight of gold and gems, and called it a “carat” which comes from “qīrāṭ” the Arabic name of the seeds. This unfaltering consistency was also put to good use in the gold and diamond mines of Kimberley, South Africa.
The leaves of carob trees are browsed by cattle in rural areas around the world, and the pods with their sugary pulp are a staple in the diet of farm animals like cattle, pigs, goats, sheep and donkeys. They are also relished by children as a sweet snack, and are a mainstay for many people in times of famine.
The timber is hard and close-grained, and is prized for carpentry and the making of utensils. It is also excellent to burn as fuel, and makes a good, slow-burning charcoal.
The pods contain a polysaccharide gum, which is odourless, tasteless and colourless, and is used commercially in many products.
After crushing to separate the seeds and pulp, carob pods are utilised for many products like: Kibbles for any animal feed (horses and ruminants); milled human food; fermentation and distillation of alcohol; and as a cacao substitute. The ground endosperm of the seed is used as a food additive, stabilizer and thickener, and as a dietary fibre in pet food. The endosperm is also used in the preparation of pharmaceutical products and cosmetics. Even the coating of the seed is used as it contains tannins for leather tanning. For commercial farmers today the main interest is in the production of seed for gum extraction.
Owing to the high sugar content of the pod and its relatively low cost, carob pulp was among the first horticultural crops used in several Mediterranean countries for the production of industrial alcohol by fermentation. In some countries like Egypt, carob syrup remains a popular drink obtained by extracting carob kibbles with water.
Because of low orchard management requirements the carob tree is suitable for rural and part-time farmers, and shows potential for planting in many regions around the world which have semi-arid and Mediterranean-like climates. The cultivation of carob trees in the marginal and prevailing calcareous soils of many of these regions remains important economically, and traditionally grafted carob trees have been inter-planted with olives, grapes, almonds, and barley.
The carob tree is also a most effective fire barrier as its leaves burn very poorly, making it most suitable for fire-wise landscaping. A fire-wise landscape uses careful planning as well as resistant plants that are strategically placed to deter the spread of fire to your home. This combined with proper maintenance, and learning to garden in ways that help to reduce fire danger by watering, pruning and maintaining your property correctly, will go a long way in protecting properties.
Carob trees remain popular ornamental shade trees for farms, large parks and gardens, and although the branches can break in high winds and storms, the trees remain useful for windbreaks and afforestation.
Health Benefits:
A study on the nutritional value of South African grown carob trees has shown that it is comparable with trees grown in other countries. The cultivars were found to be a good source of energy containing about 90% carbohydrates. The protein content was between 3 and 4% and seven essential amino acids were detected. Sucrose is the dominant sugar (up to 45%), while glucose and fructose made up the remainder.
Cultivars contained up to 36% dietary fibre and 3% polyphenols, both of which have remarkable nutritional benefits. They had low fat and sodium content; and good proportions of long-chain fatty acids, in terms of saturated to polyunsaturated fatty acids and omega-6 and omega-3 ratios.
Nine nutritionally important minerals were also detected, calcium, phosphorous, potassium, magnesium, sodium, manganese, iron, copper and zinc.
In the Kitchen:
Once you get beyond the slight stinky cheese smell, the flesh of carob pods is naturally sweet and can be nibbled on straight from the tree. The seeds are ground and used as a thickening agent, and the pods are used as a chocolate substitute, and although the flavour is not as rich as dark chocolate, it resembles milk chocolate.
The pulp can be dried in an oven and ground into a fine powder which can be added to cakes, bread, sweets, ice creams, or drinks, as flavouring and for its nutritional value. Carob powder ‘cocoa’ also has advantages over chocolate in that it has fewer calories and contains neither caffeine nor theobromine.
Ceratonia siliqua fruit - Image by Georges Tsukaïmah from PixabayCultivation:
The carob is a slow growing but long-lived evergreen tree thriving in habitats with mild Mediterranean climates with cool but not cold winters, mild to warm springs, and warm to hot and dry summers, withstanding summer temperatures as high as 40°C and hot dry winds. Mediterranean-like areas of the world range from approximately 30° to 45° in northern latitudes in the Mediterranean basin, California and Arizona, and between 30° and 40° in southern latitudes, in Australia, South Africa and Chile.
It also grows well in warm temperate and subtropical areas, and tolerates hot and humid coastal areas. The trees require no winter chilling and although they prefer milder winters they are still remarkably hardy once they are established. Young trees can be damaged when temperatures fall below -4°C, and although mature specimens are tougher, they cannot withstand winter temperatures lower than -7°C.
Be patient as carob trees grow slowly at first, but begin to bear in the sixth year of planting and may remain productive for 80 to 100 years. Like most Mediterranean trees, the carob has two main growing flushes, one in spring and the other in autumn before the winter rains, and vegetative growth slows below 10°C. Thus, it seems that this species enters some kind of ‘light’ dormancy, in most cool latitudes. However, in very warm places, and under favourable conditions, carobs grow without becoming dormant either in winter or summer.
For resistance to dry environments the carob is surpassed only by the pistachio, and the rooting habit of carob trees is also similar to pistachio, with its extensive root system penetrating deeply into the soil, where water may be available. As a xerophyte, it can survive long periods of drought and can survive dry climates with annual average rainfall between 250 and 500mm without irrigation. Although 350mm of annual rainfall is considered enough for fruit set, for commercial crops carob trees need to receive at least 500 to 550mm per year, and require 5,000 to 6,000 hours with temperatures above 9°C for the pods to ripen.
Carob trees can adapt to a wide range of soil types, except heavy clay and acidic soils. They thrive on poor sandy soils near the sea, to rocky hillsides, and deep soils, but they cannot withstand waterlogging. In areas with shallow rocky soils, tree size and productivity are reduced. The best soils are sandy well-drained loams, but calcareous soils with high lime content are also suitable. Carob also appears to tolerate soil salinity well (up to 3% in soil), and after being irrigated with saline water in the summer, carob trees can recover during winter rainfalls.
Generally, an established plant will not need to be pruned, except to remove wind damaged or diseases limbs, and the trees do not required feeding, but an occasional dose of fertiliser will do no harm.
On the basis of the flower structure, male, female, and hermaphrodite cultivars can be recognized. The female cultivars are the most important trees in commercial groves and males and hermaphrodites are normally only used as pollinators. There is no agreement on the best density of male pollinators for commercial orchards. However, there is sufficient information to recommend around 12% of pollinators. Pollination is carried out by wind and insects, and low yields are often due to poor pollination.
Harvesting:
Pods are produced after 6 to 7 years, and improved varieties of carob can bear pods within 3 to 4 years. A yield of about 2kg can be expected from a 6 year old tree, and up to 125kg of pods can be harvested from mature trees about 25 years old.
Carob trees flower in late summer and early autumn, and they are also harvested at this time. For this reason harvesting is the most labour-intensive part of carob cultivation, and care has to be taken not to damage the flowers and therefore next year's crop.
Containing a lot of sugar, carob pods need to be picked at specific times of the year, based on your intended use of their tasty seeds and pulp.
If you want to enjoy the moist pulp, you need to pick the pods in the spring while they are still green and flexible. At this stage of growth the internal pulp will have a wonderful sweet taste, and is eaten raw, while avoiding the seeds. Chewable carob pods are ready for picking when they have grown into a flattened shape with a long body.
For milling, carefully observe the tree in late summer, and shake some pods off before they naturally fall to the ground. To check the ripeness, simply bend the pod - pods that flex are not ready for milling, but a quick snap of the pod's protective sheath indicates that the dry carob is ready for picking.
Carob pods are harvested before winter and should be prodded off the tree with a pole, and they are often collected in nets or sheeting placed under the trees. After harvest, carob pods have a moisture content of 10 to 20% and should be dried down to a moisture content of 8% so the pods don’t rot.
When you pick the dry pods, they do not need to be processed immediately, as they store quite well for up to one year if they are dried thoroughly. If you have a lot of pods to store, it is good practice to lay them out in the sun on a sheet or blanket. After approximately two days of drying, these pods should have an extremely low moisture content of about 8%. As long as the pods are not exposed to any moisture during or after drying, you may store them for milling or other uses around the kitchen.
Propagation:
The slow-growing carob tree can be grown from seed. Fresh seeds germinate quickly, while dried seeds need to be scarred and then soaked in hot water for a period of time until swollen two to three times in size to improve germination. Sow in a sandy potting mix in spring or summer, in individual containers such as recycled milk cartons. Seedlings are transplanted when they are about 8 to 10cm high and have grown their first true leaves. Avoid damaging the fragile taproots when transplanting the seedlings.
Problems, Pests & Diseases:
Few pests are known to cause severe damage in carob orchards, so they have traditionally not been treated with pesticides, and only some cultivars are susceptible to mildew disease.
The biggest threat to the carob is its dislike for soggy soil and overly wet conditions which lead to stunted trees and inability to absorb nutrition, causing yellowing and leaf drop.
Low yields are often due to autumn rains which can interfere with pollination and affect fruit set. Too much summer rainfall results in the pods rotting away.
Wind can damage young trees, and strong winds can break the branches of mature trees and detach pods.