2141

8: Vegetables

Archidendron jiringa (Jack) Nielsen

Adansonia, ser. 2, 19: 32 (1979).

LEGUMINOSAE

2n = 26 (?)

Pithecellobium lobatum Benth. (1844), Pithecellobium jiringa (Jack) Prain (1897), Zygia jiringa (Jack) Kosterm. (1954).

Indonesia: jengkol, jering, jingkol, jringkol. Malaysia: jiring. Burma: tangyin, tanyeng-pen. Thailand: niang (peninsular), niang-nok (peninsular), chaniang (eastern).

Archidendron jiringa is of South-East Asian origin and occurs wild and cultivated in Malaysia, Indonesia (Java, Sumatra, Kalimantan), Brunei, Thailand, Burma and Bangladesh.

The seeds of jengkol are mainly used to add flavour to food, and are relished by Indonesians and Malaysians. To some people, however, their smell is rather offensive. Young seeds are often eaten raw. Mature seeds are prepared in several ways: 1) boiled thoroughly till the offensive smell has disappeared, and consumed with salt and grated coconut, 2) steeped for a couple of hours in salt water, before being fried in oil; this also removes most of the bad smell, 3) processed into chips ('emping' or 'kripik jengkol'); after cooking, the cotyledons are flattened by hammering them into the shape of small cakes which are sun-dried, and fried in oil before consumption, 4) buried for 14 days until they germinate, then dug up and washed clean, whilst at the same time the sprouts are cut off and thrown away ('sepi'). The latter way of preparation is said to minimize the danger of intoxication by jengkolic acid, crystals of which can cause kidney failure. It is recommended to drink much water when eating the seeds. The very young wine-red shoots are also consumed raw as vegetable.
The pods were used as a source of purple dye for silk in the past; they are still used as a shampoo. In Kalimantan, the bark is used for dyeing matting black; to obtain this colour the mat is boiled with extract from the bark and then immersed in mud.
The old leaves, burnt to ashes, are used against itching. The ashes of young leaves are used as wound powder for cuts (e.g. circumcision).
The timber is soft, easy to saw and to work with; therefore it is only suitable for cabinet work, interior joinery or as firewood.

In its area of distribution, jengkol is a popular food and local production is considerable; however, no statistics are available. Fruits (containing the seeds) are traded on local markets only.

Per 100 g edible portion, young immature seeds contain: water 93 g, protein 3.5 g, fat 0.1 g, carbohydrates 1.7 g, Ca 21 mg, P 25 mg, Fe 0.7 mg, vitamin A 240 IU, vitamin B 0.1 mg, vitamin C 12 mg. The energy value is 92 kJ/100 g. Ripe seeds consist for about 70% of starch. Jengkol has a good amino-acid profile, and is rich in cysteine.
The seeds contain a volatile oil consisting of an allyl sulphur compound, and an alkaloid, which act as diuretic. They also contain 1.3—1.8% or an average of 225 mg/seed of the toxin jengkolic acid (C₇H₁₄O₄N₂S₂). Excessive consumption may lead to the 'kejengkolan' disease, caused by crystallization of jenkolic acid in the kidneys and bladder, with the following symptoms: renal hyperemia, oliguria to no urination at all, and pain when urinating.
Seed weight is approximately 15 g per seed.

Tree, up to 20 m tall with grey smooth bark, white wood and terete, glabrous branchlets. Leaves 2-pinnate, up to 25 cm long; petiole 2—6 cm long; leaflets 2—3 pairs per pinna, ovate-elliptical to oblong, 8—15 cm x 4—5 cm, opposite, chartaceous, glabrous, dark violet-red when young. Inflorescence axillary, paniculate, up to 20 cm long; flowers sessile, 4—7 together in a pseudo-umbel on a short peduncle, 5-merous, bisexual; calyx cup-shaped; corolla tubular, 4—5 mm long, 5-lobed, white; stamens numerous, at base united into a tube, free filament parts ca. 5 mm long. Fruit a legume, compressed, falcate or twisted in a wide spiral, more or less deeply lobed along the ventral suture between the seeds, 20—25 cm x 3—4 cm, woody, greyish, glabrous, dehiscent along the ventral suture. Seeds compressed orbicular, ca. 35 mm x 10 mm, testa yellow-green when young, turning dark brown. Germination is hypogeal and the first five leaves are scale-shaped.
Archidendron jiringa starts bearing 5—6 years or more after sowing. Flowers open in the evening after dark and pollination is effected by moths and other insects. Flowering and fruiting are year-round, but peak periods occur. It takes 40—50 days from anthesis to mature fruits.
There are a few forms differing in size and tenderness of the seeds. They are sometimes distinguished in Indonesia as 'jingkol' or 'jengkol gobang' with large, somewhat hard and slightly bitter seeds, and 'jringkol' with smaller, more tender and less bitter seeds.
Several other Archidendron species in South-East Asia also produce edible seeds (e.g. Archidendron bubalinum (Jack) Nielsen, Archidendron quocense (Pierre) Nielsen, Archidendron microcarpum (Benth.) Nielsen, but they seem more poisonous. Only Archidendron jiringa is purposely cultivated in fields, around villages and in home gardens.

Archidendron jiringa occurs in primary and secondary rain forest and in evergreen forest. Trees are often spared when the forest is cut down. It prefers a pervious soil and high rainfall. It is recorded from sandy soil, lateritic soil, reddish sandy clay, flat land and low undulating hills, from sea-level up to 1000(—1600) m altitude.

Jengkol is propagated by seed. Squirrels (Callosciurus notatus) eat the seeds and facilitate its distribution. In cultivation, planting distances are 10—15 m. Jengkol has a number of pests in common with other leguminous trees and shrubs such as the pod-borers Mussidia pectini cornella and Cryptophlebia ombrodelta, and the caterpillars of the leaf-feeder Eurema blanda, one of the most common butterflies in Java.
A mature tree produces from 1000—4000 seeds/year. The main harvest period in Java is in July — August, the after-crop in December — February. Jengkol is sold in the market by number of seeds. For transport, seeds, in particular young ones, should not be removed from the pods to avoid desiccation. Processed into chips, they can be stored for a long period.

Archidendron jiringa will remain an important relish. Very little information has been gathered on this tree in recent times. More research might be rewarding, in particular on methods to reduce the danger of intoxication, to control insect pests without spraying pesticides and on methods for clonal propagation.

Kartawinata, K. & Sastrapradja, S. (Editors), 1979. Kayu Indonesia [Indonesian timbers]. LBN-LIPI 14. Project of Indonesian Economic Plant Resources No 55. LBN-LIPI, Bogor, Indonesia. p. 37.
Nielsen, I.C., 1985. Leguminosae - Mimosoideae. In: Smitinand, T. & Larsen, K. (Editors): Flora of Thailand. Vol. 4(2). The Forest Herbarium, Royal Forest Department, Bangkok, Thailand. pp. 217-219.
Soeparma Satiadiredja, 1950. De teelt en het gebruik van Indonesische groenten en toekruiden [The cultivation and use of Indonesian vegetables and condiments]. Wolters, Groningen, the Netherlands. p. 67.
Suhaila Mohamed, Mohamed Shamsuddin Abd. Rahman, Sabturiah Sulaiman & Fauziah Abdullah, 1987. Some nutritional and anti-nutritional components in jering (Pithecellobium jeringa), keredas (Pithecellobium microcarpum) and petai (Parkia speciosa). Pertanika 10(1): 61-68.

H. Wiriadinata

Wiriadinata, H, 1993. Archidendron jiringa (Jack) Nielsen. In: Siemonsma, J.S and Piluek, K (Editors): Plant Resources of South-East Asia No 8: Vegetables. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea