Common Name: Carob

General Information

Ceratonia siliqua is an evergreen shrub or, more commonly, a tree with a hemishperical crown; it usually grows up to 10 metres tall, occasionally to 15 metres, with a crown that can be up to 14 metres wide[]..
The plant is harvested from the wild for local use as a food, medicine and source of materials.. The tree is sometimes cultivated for its edible seeds and seed pods, and is commonly grown as an ornamental in Mediterranean climates[].

Known Hazards

None known

Botanical References

,

Range

Mediterranean Region - Spain, east to Greece and Turkey, south to Israel, Jordan and Egyptian Sinai; Morpcco, Algeria, Tunisia

Habitat

Rocky places near the sea shore[]. Dry hillsides in garrigue, coastal and submaritime maquis and in the transitional zone between Mediterranean scrub and Sahara; at elevations up to 600 metres[].

Properties

Edibility Rating
Medicinal Rating
Habit	Evergreen Tree
Height	8.00 m
Growth Rate	Slow
Pollinators	Bees, Insects, Wind
Self-fertile	No
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Ceratonia siliqua is a plant of Mediterranean climates with hot, dry summers and cooler moist winters - it also thrives in warm temperate regions, subtropical areas and hot, humid coastal areas, but does not generally thrive outside those areas. It thrives where the mean annual rainfall is within the range 250 - 550mm[]. Young plants are very frost tender, but older plants develop some resistance and can tolerate ocasional lows to -5°c so long as the soil is freely draining. Young growth in spring, even on mature plants, is frost-tender and so it is best to grow the plants in a position sheltered from the early morning sun[]. Trees can withstand summer temperatures of 40°c and hot dry winds. They need from 5,000 - 6,000 hours with temperatures above 9°c in order for the pods to ripen[]. The plants generally grow well in the more southerly parts of California[].
Requires a very sunny position in any well-drained moderately fertile soil[]. Does well in calcareous, gravelly or rocky soils and also tolerates fairly salty soils[, , ]. Tolerates salt laden air[] and urban pollution[]. Tolerates a pH in the range 6.2 to 8.6. The tree is very drought resistant, thriving even under arid conditions, the roots penetrating deep into the soil to find moisture[, , , ].
The carob is sometimes cultivated, especially in Spain, as a food crop and source of gum. There are some named varieties that have larger seedpods containing more pulp and with a greater sugar content[, , ].
Mature trees in a suitable environment can yield up to 400 kilos of seedpods annually[].
Plants are often slow-growing[].
The seed is very uniform in size and weight, it was the original 'carat' weight of jewellers[, ].
A dioecious species, both male and female forms are generally required for seed to be produced. The flowers initially appear to be bisexual, but usually one sex is suppressed during late development of the functionally male or female flowers. Occasional trees produce functional bisexual flowers[].
Although many species within the family Fabaceae have a symbiotic relationship with soil bacteria, this species is said to be devoid of such a relationship and therefore does not fix atmospheric nitrogen[].

Edible Uses

Seedpods - raw or ground into a powder[, , , , ]. The seedpods are filled with a powdery, saccharine pulp and can be eaten both green or dried[]. Rich in sugars and protein, the pulp is very sweet but fibrous[]. The pulp can be ground into a fine powder and used as a chocolate substitute in cakes, drinks, sweets etc[, ]. The seedpods can be 10 - 30cm long, 15 - 35mm wide and 10mm thick[, ]. The pods contain about 55% sugars, 10% protein and 6% fat[, , ].

Seed - rich in protein. A flour is made from them which is 60% protein, it is free from sugar and starch and is suitable for baking[, ]. It can be used as a chocolate substitute[].

An edible gum is extracted from the seed, a substitute for Gum Tragacanth (see Astragalus species)[]. A stabilizer and thickening agent, it can also be used as an egg substitute[, , , , ]. A widely used food additive, it has the Euro number E410[]. The gum is obtained from the endosperm, it is a polysaccharide comprised of mannose and galactose sugars. This gum has a high viscosity in solution with water, and is able to form very stable, viscous solutions in high dilution (1% or lower)[]. One hundred kilos of seeds can yield 20 kilos of pure, dry gum[].

The roasted seed is a coffee substitute[, , ].

Medicinal

The pulp in the seedpods of carob is very nutritious and, due to its high sugar content, sweet-tasting and mildly laxative[]. However, the pulp in the pods is also astringent due to the presence of tannins and, used in a decoction, will treat diarrhoea and gently help to cleanse and also relieve irritation within the gut[, ]. Whilst these appear to be contradictory effects, carob is an example of how the body responds to herbal medicines in different ways, according to how the herb is prepared and according to the specific medical problem[]. The seedpods are also used in the treatment of coughs[].
A flour made from the ripe seedpods is demulcent and emollient[]. It is used in the treatment of diarrhoea[].

The seed husks are astringent and purgative[].

The bark is strongly astringent[]. A decoction is used in the treatment of diarrhoea[].

Agroforestry Uses:

Traditionally, grafted carob trees (Ceratonia siliqua) have been interplanted with olives (Olea europaea), grapes (Vitis vinifera), almonds (Prunus armeniaca) and barley (Hordeum vulgare) in low-intensity farming systems in most producing countries in the Mediterranean[].
The carob tree is often recommended for the reforestation of degraded coastal zones threatened by soil erosion and desertification. It also has been recommended for planting as a windbreak around orchards, and could even have some use for buffering noise from factories, roads and railways because of its dense foliage[].

Other Uses

The gum obtained from the seeds has a wide range of uses in addition to food and medicine. It is used, for example, as an emulsifier in cosmetics, it is included in products for coeliacs because of its soothing effect upon the digestion, is used to thicken colours in the textile industry, and added to concrete mixes to strengthen solidification[].

A flour made from the seedpods is used in the cosmetic industry to make face-packs[].

Tannin is obtained from the bark and seedpods[, ].

The wood is hard, close-grained and lustrous. Highly valued by turners for making utensils etc, it is also used for marquetry and walking sticks[, , , , ].
The wood makes an excellent fuel and a slow-burning charcoal[].

Propagation

Seed - pre-soak for 24 hours in warm water prior to sowing. If the seed has not swollen then give it another soaking in warm water until it does swell up. Sow in a greenhouse in mid spring[]. Germination is best at around 25°c, and should take place within 2 months. As soon as they are large enough to handle, prick the seedlings out into individual deep pots and grow them on in a greenhouse for at least their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts. Give them some protection from the cold for their first few winters outdoors.
Cultivated forms are propagated by means of grafting on to seedling rootstocks[].