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Tamarind: a multipurpose tree

July 09, 2007

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AMONG fruit trees of the tropics, none is more widely distributed and appreciated as an ornamental tree than the tamarind. Tamarind is best known for its mouth-watering fruit. It is commonly known here as “Imli”. Tamarind fruit is marketed worldwide and used in sauces, syrups and processed foods. The soft, succulent pulp is used in confectionery and as an ingredient in curries, chutneys, preserves, pickles and beverages.

The tender pods can be eaten as a vegetable--cooked or pickled. Tamarind contains pectin which is used in manufacturing process of jams and jellies. Once the seeds are extracted and the pods removed, tamarind pulp can be stored for several months in compressed form.

Iimli is also used as an alternative to tomatoes when tomato is scarcely available. The price of Imli is cheap compared to tomato and it is available throughout the year in market.

Tamarind tree can grow up to 25 meters with a spread of 12 meters and stays evergreen in regions without a dry season. Tamarind timber consists of hard, dark red heartwood and softer, yellowish sapwood. The leaves consist of 10 to 18 leaflets. The tree produces brown pod-like fruits, which contain pulp and hard-coated seeds. The seeds can be scarified to enhance germination. Its leaves, flowers, and even seedlings, make a tasty broth. The foliage is good for cattle fodder. It is also used as mulch for tender plants and it composts into good manure.

The pulp of the fruit is used as a spice in Asian cuisine. The pulp of a young fruit is very sour, whereas a ripened fruit is sweet and can be used in desserts and drinks. The pulp, leaves, and the bark also have medicinal uses. Due to its denseness and durability, tamarind heartwood can be used in making furniture and wood flooring.

Tamarind grows well in deep sandy loam soil and tolerates limited salinity. It is a highly sun-loving plant of warm open areas. It likes humid tracts. Annual rainfall of around 70-200 cm is ideal for this tree and draught is injurious.

Tamarind stock is raised in nurseries. The fruit is dispersed widely because of its taste. The seed germinates easily. Tamarind has 1-2 cm thick dark-grey bark with longitudinal fissures. The leaves are pinnate compound with 5-10 cm long rachis. Each leaf has 10-20 pairs of opposite leaflets. The canopy is beautiful, umbrella-like and the foliage dense. Tamarind bears reddish brown inflorescence in sub-terminal racemes during May-June. The fruit pods are 5-8 cm long and 2-4 mm thick. It fruits during August-September and ripens by March- April.

Cultivation: Nursery-grown trees are usually transplanted during the early rainy season. If kept until the second rainy season, the plants must be cut back and the taproot trimmed. Spacing may be 33ft to 65 ft between trees each way, depending on the fertility of the soil. With sufficient water and regular weeding, the seedlings will reach 2 ft the first year and 4 ft by the second year. The tree bears fruit abundantly up to an age of 50-60 years or some times longer, then productivity declines, though it may live another 150 years.

Small seedlings are susceptible to browsing damage and weed competition so some initial protection and spot weeding may be necessary. Young trees might also be tied to stakes to encourage a straighter stem form. In more arid climates, irrigation during the first dry season speeds growth substantially. Apart from these suggested treatments, once planted, tamarind trees require little management. Tamarind starts bearing fruit at about 10 years, depending upon the environment.

Harvesting: Tamarinds may be left on the tree for as long as six months after maturity so that moisture content will be reduced to 20 per cent or lower. Fruits for immediate processing are often harvested by pulling the pod away from the stalk which is left with the long, longitudinal fibres attached. In Pakistan and India, harvesters may merely shake the branches to cause mature fruits to fall and they leave the remainder to fall naturally when ripe. Pickers are not allowed to knock the fruits off with poles as this would damage developing leaves and flowers. To keep the fruit intact for marketing fresh, the stalks must be clipped from the branches so as not to damage the shell.

A mature tree may annually produce 330 to 500 lbs (150-225 kg) of fruits, of which the pulp may constitute 30 to 55 per cent, the shells and fibre, 11 to 30 per cent, and seeds, 33 to 40 per cent.

Preservation: To preserve tamarinds for future use, they may merely be shelled, layered with sugar in boxes or pressed into tight balls and covered with cloth and kept in a cool, dry place. For shipment to processors, tamarinds may be shelled, layered with sugar in barrels and covered with boiling syrup. In India, the pulp with or without seeds and fibre is mixed with salt (10 per cent), pounded into blocks, wrapped in palm leaf matting, and packed in burlap sacks for marketing. To store for long periods, the blocks of pulp may be first steamed or sun-dried for several days.

Uses: Tamarind fruits are brown, fleshy pods that are fibrous, thick and sticky. They are sausage shaped and covered in faint fuzz, like a kiwi fruit. Inside they contain a sharp-tasting pulp and several flat shiny brown seeds. Young seeds contain amber, sweet-tasting oil (10 to 15 per cent by weight). It produces many valued food, medicine, wood and construction products. Drought resistant and strong, it performs well as a windbreak, preventing soil erosion and protecting people, crops and animals in harsh environments.

Tamarinds also provide a handsome element in thousands of park, garden and roadside landscapes. The American pharmaceutical industry processes 100 tonnes of tamarind pulp annually. The fruit is said to reduce fever and cure intestinal ailments. Its effectiveness against scurvy is well documented. It is a common ingredient in cardiac and blood sugar reducing medicines.

The pulp is also used as an astringent on skin infections. Leaves are used in treatment of swellings, tumour, ring worm, blood disorders, small-pox, eye diseases, earache etc. Flowers are useful in treatment of urinary troubles. Fruits are sour, tasty, indigestible, and astringent to bowels, laxative, heating, heart tonic, whereas seeds are useful in treatment of vaginal discharges and ulcers. According to the Unani systems of medicine, its bark is astringent and tonic whereas fruits are sour, sweetish, laxative and useful in liver complaints, vomiting, thirst, scabies, and sore-throat, stomatitis and blood disorders.

Seeds are astringent and aphrodisiac. In case of snake or scorpion bite, they cut the wound with the help of sharp knife and after rubbing Imli seeds in stones; stick the seeds in contact with the affected portion. The seeds are capable of absorbing the poison. When seeds soak all the poison, it drops automatically. The flowers are rated as a good source of nectar for bees. The honey is golden-yellow and slightly acidic in flavour.

Tamarind seeds yield amber oil used for illumination and as a varnish especially preferred for painting dolls and idols. The oil is said to be palatable and of culinary quality.

In India and Southeast Asia, tamarind seeds are also crushed and boiled to produce a paste that is used as a roofing material. This material is highly resistant to sea water and salt spray corrosion. The powder made from tamarind kernels has been adopted by the Indian textile industry as 300 per cent more efficient and economical than cornstarch for sizing and finishing cotton, jute and spun viscose, as well as having other technical advantages.

It is commonly used for dressing homemade blankets. Other industrial uses include employment in colour printing of textiles, paper sizing, leather treating, the manufacture of a structural plastic, and glue for wood, a stabiliser in bricks, a binder in sawdust briquettes, and a thickener in some explosives. It is exported to Japan, the United States, Canada and the United Kingdom.

Tamarind wood burns well as fuel and make a high-grade charcoal for cooking. The wood ash and bark contain high tannin concentrations. Sometimes compared to the coconut as another “tree of life", it is widely adaptable and easily managed. Tamarind wood, weighing about 20-25 kg per cubic foot, is somewhat hard to work. It is also not very durable in outdoor structures exposed to weather. The sapwood of the tamarind tree is pale-yellow. The heartwood is rather small, dark purplish-brown, very hard, heavy, strong, durable and insect-resistant. It bends well and takes a good polish and, while hard to work, it is highly prized for furniture, panelling, wheels, axles, gears for mills, ploughs, planking for sides of boats, wells, mallets, knife and tool handles, rice ponders and pestles.