Jelutong (FAO, NWFP 6)
- Extract from : NWFP 6. Coppen J.J.W., 1995. Gums, resins and latexes of plant origin. FAO, Rome. 142 p. (Non-Wood Forest Products, 6). on line
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Contents
DESCRIPTION AND USES
Jelutong is the coagulated gutta-like material obtained from the latex of wild trees of Dyera species which are indigenous to certain parts of Southeast Asia.
Before Hevea plantations were developed in Southeast Asia, jelutong was produced and exported for the manufacture of inferior rubber items, in which elasticity was not a prime consideration. With the advent of large-scale rubber production, exploitation of jelutong ceased almost completely. In the 1920s it regained importance as a basic ingredient in chewing gum, sometimes in admixture with chicle, and since then (at least into the 1960s, when WILLIAMS (1963) reviewed it) this has been its main use. It has a consistency comparable to that of chicle, but the additional advantage that its properties also make it suitable for "bubble" gums.
WORLD SUPPLY AND DEMAND TRENDS
Markets
The United States has traditionally been the major importer of jelutong, although it is almost all shipped via Singapore rather than direct from source. During the period of peak production in the early 1900s, consumption averaged almost 14 000 tonnes annually. For the five years 1957-61, US imports averaged approximately 1 300 tonnes, a ten-fold decrease.
Exports of jelutong from Indonesia for the six years up to 1993 (Table 33) averaged just over 3 600 tonnes/year, with a peak of 6 500 tonnes in 1990. Most, or all of it, has been exported to Singapore and it is not known how much of this has been re-exported to the United States. Some jelutong is exported directly to Japan, and in Europe, Italy is the main importer.
Unlike the other masticatory gums, therefore, there appears to have been some upturn in use of jelutong in the recent past, at least compared with thirty years ago. It remains to be seen whether the downward trend of the last four years continues.
Supply sources
In the past, Indonesia (principally Kalimantan) has been the most important supplier, followed by Malaysia (especially Sarawak). Today, Indonesia is believed to be the main source of jelutong, with the level of production indicated by the exports cited above (and Table 33).
Quality and prices
Dyera costulata appears to furnish an intrinsically better quality product than Dyera lowii, although in former times the method of coagulation of the latex and subsequent handling were also important factors; the moisture content of the jelutong was another important determinant. The proportion of gutta-type material is about 20% (on a moisture-free basis), most of the balance being resin.
Average FOB export values for raw, pressed and refined Indonesian jelutong were in the range US$ 720-750/tonne in 1993, compared to US$ 980-1 060/tonne two years earlier.
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PLANT SOURCES
Botanical/common names
Family Apocynaceae:
- Dyera costulata (Miq.) Hook.
- Dyera lowii Hook. (Accepted name : Dyera polyphylla)
Description and distribution
Both species grow to be very large trees with a straight trunk, up to 50-60 m tall and 2 m in diameter in fully developed trees. They are widely distributed in the Malay Peninsula, and the islands of Sumatra and Borneo. Dyera costulata is the only species found in Malaysia and extends into the southernmost part of Thailand. Both species are found scattered throughout Sumatra and Borneo.
Dyera costulata is found in the flood-free lowland and upland areas (up to about 800 m), while Dyera lowii occurs in the low-lying swamplands.
The term jelutong is used to describe both the tree and the coagulated latex. Pontianak is an older term for the coagulated product.
COLLECTION/PRIMARY PROCESSING
Older, indiscriminate methods of tapping entailed making a series of cuts around the trunk and removing the bark. The trees were retapped above the first cuts approximately every 8 days until the whole of the bark had been removed from near the ground to as high as the tapper could reach.
Recognizing the need to abandon such damaging practice, regulations were gradually introduced from the 1930s describing methods based on a "herring bone" system. V-shaped cuts are made in the trunk, commencing at a height of about 1.5 m, with a central, vertical channel leading to a bamboo cup or cloth bag placed at the base of the trunk, into which the latex flows. A narrow strip of bark is removed from the lower surface of the cut and repeated at 2-3 day intervals down the trunk of the tree. In Malaysia, tapping was restricted to trees of 70 cm diameter and greater, on a panel not to exceed half the trunk circumference. Size restrictions on the smaller Dyera lowii were slightly reduced. Dyera trees have a moderately good bark recovery, although not as rapid as rubber (Hevea brasiliensis) and the same panel may be retapped after a rest period of about two years.
After first straining the freshly collected latex through a fine-mesh sieve, it is coagulated in one of two ways. In the cold method, dilute phosphoric acid is added to the latex, which is then set aside to stand for 3 days; at the end of this time coagulation is usually complete. In the hot method, which usually gives better results, phosphoric acid is added to the latex and the mixture is boiled with stirring; coagulation is usually complete within 2-3 minutes.
Before shipping to the factory for further processing, the initial coagulant is subjected to some preliminary treatment. This usually entails repeated boiling in hot water to remove soluble impurities; the coagulant is then pressed into blocks in readiness for shipment. If there is
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likely to be some delay before transportation the blocks are stored under water to prevent oxidation, discolouration and mould formation.
Yields
Although there can be significant tree-to-tree variation, and yields of latex also depend on the method of tapping which is used, Dyera costulata is generally regarded as being a higher latex yielder than Dyera lowii. Dyera costulata trees growing in Malaysia have been found to average about 11 litres of latex a month when tapped daily, and to yield about 3.5 kg of coagulated jelutong. Some old studies have found that upward tapping is more productive than tapping in a downward direction.
VALUE-ADDED PROCESSING
Further processing entails repeated washing (sometimes with boiling) and drying to bring it to a lower, more consistent moisture content and pressing into sheets. Recent trade statistics for Indonesian jelutong indicate that it may be exported in the raw, pressed, refined or "other" form, but the nature of modern-day refining or other treatment that it may receive is not known.
PRODUCTS OTHER THAN LATEX
Apart from minor timber use, there are no other products of commercial value.
DEVELOPMENTAL POTENTIAL
Information acquired in Sarawak shows that Dyera costulata takes nearly 60 years to attain a girth of about 1.8 m, and until it reaches this size yields of latex are such that it is not worth tapping. On this time scale, plantations established for latex production could not possibly be economic. Dyera lowii has been tested as a plantation crop in Sarawak, and although it reaches a size at which it can be tapped rather more quickly than Dyera costulata, 30-35 years of age, this is still too long for a tree in which the latex would be the principal product.
SELECTED BIBLIOGRAPHY
- BROWNE, F.G. (1952) Jelutong. pp 2-6. In Sarawak Forestry Department Leaflet No. 1.
- SMITH, E.H.G. (1940) Chicle, jelutong and allied materials - a review. Bulletin of the Imperial Institute, 38, 299-320.
- STANISLAUS, P.R. (1955) Jelutong: a Sarawak latex and timber tree. Wood, 20(4), 169.
- WILLIAMS, L. (1963) Laticiferous plants of economic importance. IV. Jelutong (Dyera spp.). Economic Botany, 17, 110-126.
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| 1988 | 1989 | 1990 | 1991 | 1992 | 1993 | |
|---|---|---|---|---|---|---|
| Total | 2358 | 5373 | 6495 | 3700 | 2712 | 1182 |
| Of which: | ||||||
| Raw | 48 | 612 | 1444 | 552 | 313 | 6 |
| Pressed | 932 | 838 | 1393 | 695 | 630 | 222 |
| Refined | 1378 | 2472 | 1958 | 1335 | 1063 | 516 |
| Other | - | 1451 | 1700 | 1118 | 706 | 438 |
| Of which to: | ||||||
| Singapore | 2358 | 5339 | 6287 | 3039 | 2145 | 751 |
| Japan | - | - | 56 | 443 | 446 | 268 |
| Italy | - | - | 38 | 57 | 121 | 141 |
| France | - | - | 101 | - | - | - |
| Korea, Rep. of | - | - | 13 | 81 | - | - |
| China (Taiwan) | - | - | - | 80 | - | - |
| Malaysia | - | 34 | - | - | - | - |
| Hong Kong | - | - | - | - | - | 22 |
Source: National statistics
