Common name: Kokum

Kokum is a Mangosteen (Garcinia mangostana) relative originating in humid tropical India, its natural range limited to the Western Ghats and the West coast of the sub-continent, extending from near Matheran, in the hills to the east of Mumbai (Bombay), south through the states of Goa and Karnataka to Kerala.

It is a slow-growing tree, to heights of up to 20 m (66 ft). However, it is more typically 10 to 15 m (33 to 50 ft) tall with a slim, low-branching trunk supporting a densely leafy pyramidal crown. The bark is dark grey or dark brown, scaly, rough and sometimes mottled by lichens, mosses and algae, which thrive in the humid conditions in which the tree grows.

Leaves are lance-shaped or elongated-oval, 5 to 10 cm (2 to 4 in) long, crimson red and soft when they emerge, becoming dark glossy green with a leather texture. Arranged in pairs along stems, they remain on the tree in all seasons.

Flowers are small with fleshy, waxy pink petals and with female and male flowers on separate trees. They are borne directly on the stems, singly or in clusters of up to four and bloom in the dry winter season. They are followed on female trees by small round fruit, 3 to 4 cm (1.2 to 1.6 in) in diameter.

The fruit are green when young, become dark purple-red when ripe and have a thick rind that encloses soft, juicy pulp embedded with six to eight kidney-shaped seed. Kokum is a heavy bearer, each female tree producing hundreds of fruit that ripen around the start of the rainy season.

Use

The seed yield 25 to 35% of an edible, white or pale yellow buttery fat known as 'Kokum Butter'. It is produced by grinding, steaming and then pressing the seed to release the fat, which is then filtered and churned into a solid buttery mass. The leftover seed cake is high in protein and is used mainly as an ingredient in livestock feed.

Kokum butter has a melting point of around 40°C (104°F), remaining solid at room temperature. Its melting properties and buttery consistency make it suitable for confectionery, including use as a Cocoa Butter Equivalent (CBE) to extend or replace Cocoa butter (from Theobroma cacao) in chocolate manufacturing. It is also widely used in its native range as a substitute for Gee, the clarified dairy butter common in Indian cooking. And it is an ingredient in cosmetics, especially skin moisturising, lip balm and lipstick products.

The fruit rind is juicy with a sour flavour and is made into a syrup (cordial), beverage base, or dried as a souring agent.

The syrup, known as 'Kokum syrup' is made by mixing the rind with cane sugar and packing the mixture into sealed drums left to stand. After standing for a week, the mixture is pressed and strained to produce the syrupy liquid, which is usually bottled. It is an intensely deep purple-red syrup with a pleasing fruity taste and is served diluted with tap or soda water to make a refreshing drink.

Kokum rind is indispensable in making 'Sol Kadi', one of southern India's most popular beverages. A vividly pink drink, it is made by soaking the rind in hot water to extract the colour and flavour, then mixing the resulting liquid with fresh coconut milk, salt, garlic and green chillies.

Some of the rind is also usually reserved for drying (after brining) to make a souring agent known as 'Malabar tamarind', commonly used in southern Indian cooking, especially fish curries.

Wild trees are now threatened by the loss of natural habitat, which has caused the species to be listed as vulnerable by the International Union for Conservation of Nature and Natural Resources (IUCN).

Health use

The properties of the seed fat lend to its use as an ointment base for adding medicinal ingredients, such as liniment ointments for treating sore muscles and strains. It is also used in its pure form to soothe chapped or cracked lips, fingers and feet.

The rind is rich in hydroxycitric acid, a biologically active plant metabolite sometimes touted as an anti-obesity drug, reportedly inhibiting the conversion of carbohydrates to fats. Hydroxycitric acid is also present in high concentrations in the fruit rind of Garcinia cambogia  (Garcinia gummi-gutta). 

Climate

Kokum grows naturally in humid subtropical and tropical lowland to mid-elevation climates, generally frost-free areas with annual lows of 18 to 25°C annual highs of 27 to 35°C, annual rainfall of 2000 to 5000 mm and a dry season of 7 months or less.

Growing

New plants are usually started from seed and cuttings, with cuttings from known female and male trees considered best practice to establish a good male to female ratio for successful pollination and fruit production. The seed are very slow to germinate, and seedling trees only start to flower and bear fruit at about seven to eight years old. Yields vary considerably but average around 12 kgs (26 lbs) of fruit per tree per year.

Performs best on free- to slow-draining clay and loam soils of a moderately acid to neutral nature, generally with a pH of 5.0 to 7.5, and on sites with full to partial sun exposure. It has good tolerance to permanently wet or waterlogged soils.

Problem features

There does not appear to be any records of escape and naturalisation anywhere in the world. The likelihood of it becoming a problem weed is low due to the relatively large size of the fruit and seed, which makes them not easily dispersed.

Books

• Attokaran, M. 2011, Natural food flavors and colorants, Institute of Food Technologists, Wiley-Blackwell Publishing, Oxfordshire

• Dastur, J. F. 1964, Useful plants of India and Pakistan : a popular handbook of trees and plants of industrial, economic, and commercial utility, 2nd ed., D. B. Taraporevala Sons, Bombay

• Farooqi, A. A. & Sreeramu, B. S. 2004, Cultivation of medicinal and aromatic crops, Hyderabad University Press, Hyderabad

• Gunstone, F. D. 2011, Vegetable oils in food technology : composition, properties and uses, 2nd ed, Wiley-Blackwell, Hoboken, New Jersey

• Jamieson, G. S. 1943, Vegetable fats and oils : their chemistry, production, and utilization for edible, medicinal and technical purposes, 2d ed, Reinhold, New York

• Janick, J., & Paull, R. E. 2008, The encyclopedia of fruit & nuts, CABI Publishing, Wallingford, Oxfordshire

• Martin, F. M., et al. 1987, Perennial edible fruits of the tropics : an inventory, U.S. Dept. of Agriculture (USDA), Agricultural Research Service, U.S. Government Printing Office (GPO), Washington, D.C.

• Parrotta, J. A. 2001, Healing plants of peninsular India, CABI Publishing, Wallingford, Oxfordshire

• Seidemann, J. 2005, World spice plants: economic usage botany taxonomy, Springer-Verlag, Berlin