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1

INTRODUCTION

Apart from essential oils, which provide an array of flavours and fragrances, gums, resins and latexes are perhaps the most widely used and traded category of non-wood forest products other than items consumed directly as foods, fodders and medicines. A recent estimate put the value of the world market for gums used as food additives at about US$ 10 billion in 1993, of which the two largest "forest" gums (gum arabic and locust bean) accounted for just over 12%; the remainder were mainly the seaweed gums, starches, gelatin and pectin (NAUDE, 1994). This takes no account of non-food uses of gums.

Some idea of the quantities of natural gums and resins which enter international trade can be gained by examining trade statistics. Imports into the European Community of "natural gums, resins, gum-resins and balsams", excluding gum arabic, are given in Table 2 for the period 1988?93. Annual imports averaged approximately 20 000 tonnes. Inclusion of gum arabic (Table 6) adds a further 28 000 tonnes to this figure.

Indonesia, India and the People's Republic of China are among the world's biggest producers of gums and resins, and exports from these countries are shown in Tables 3, 4 and 5, respectively. Note that some of the figures in Table 3 (and Table 2, Brazil) are distorted by the inclusion of pine resin/. Sudan (Table 12) and Indonesia are the world's two biggest exporters of natural gums and resins.

The uses of the gums discussed in this report are elaborated in the sections concerned, but they embrace food, pharmaceutical and miscellaneous technical applications. In the food industry, advantage is taken of their thickening, stabilizing, emulsifying and suspending properties and they are employed in a very wide range of products, both foods and drinks. In the pharmaceutical industry they are used as binding agents in tablets and as suspending and emulsifying agents in creams and lotions; some have specific applications in the dental and medical fields. Miscellaneous end users include the printing and textile industries.

Resins, including oleoresins and balsams, have an equally diverse range of applications, although the volumes which are traded have declined considerably (with the exception of pine resin) over the last 50 years.

Their use in paints, varnishes and lacquers, in particular, has suffered as cheaper, synthetic alternatives have become available. Some resins, however, are still used in this way. Others, especially the soft resins and balsams, are used as sources of fragrances and pharmaceuticals, usually after preparation of a suitable solvent extract or distillation of a volatile oil.

The decline in use of certain types of natural product at the expense of synthetics, referred to above in the case of resins, has been even greater for most of the latexes discussed in this report. In their heyday in the early part of the century, they were produced in large volumes to meet the needs of the growing chewing gum industry and for use in specialized applications such as insulating materials and the manufacture of golf balls. Today, their use is but a fraction of what it was.

The decline in use of many gums, resins and latexes is a reflection of industry's general preference for raw materials which are of consistent, predictable quality, which are not subject to the vagaries of weather, insect pests and economic and political stability in producing countries, and which are available at an attractive price. In many cases, the synthetic alternatives which meet these needs are also technically superior to the natural products they replace. Notwithstanding these remarks, however, some natural gums and resins do enjoy continued use - gum arabic is a prime example - either because they have functional properties which synthetics cannot match or because they are available at a price which makes it cost-effective to continue to use them. In food use, particularly, any change of formulation requires a change in the labelling of the end product, which is very costly to the manufacturer and not something which is done without very good reason. (Equally, if a switch is made away from using a natural gum then that market cannot easily be regained at a later date). There are also some marketing advantages for manufacturers in being able to label their products as containing natural, rather then synthetic, additives.

The above remarks apply, essentially, to the large-scale consumer markets and take no account of the use of gums, resins and latexes at the local level, by the communities which collect them. This use is not easily quantified but is clearly very important. Some of the resins are used for making torches and for caulking boats and baskets, or as sources of incense. Many are used for medicinal purposes.

The permitted use of gums in foods is a subject of some concern and much legislation. Recent changes in the toxicological status of gums, including the exudate and seed gums discussed in this report, have been summarized by ANDERSON (1991). Present and future European legislation on food hydrocolloids (gums) has been summarized by GRAY and PENNING (1992). Where applicable, specifications for gums (and resins) used in foods and dealt with in this report have been included in the selected bibliography at the end of each section. However, any prospective new producer or exporter of gums intended for food use should consult either their national standards organization (for information on local quality requirements) or international organizations or importers (for up-to-date advice on requirements in end-user countries).

OPPORTUNITIES FOR DEVELOPMENT OF NEW OR IMPROVED SOURCES OF GUMS, RESINS AND LATEXES

ROBBINS (1988) has stated, "in spite of the problems which have beset the gums market in recent years, the fact remains that in many cases the gums provide a valuable source of income for many poor smallholders or itinerant labourers, either in very poor countries or in the poorest regions of rather more developed countries. As such they are important commodities ...". This remains true today. Tens of thousands of people worldwide, living in regions ranging from semi-arid lands to moist rainforest, depend on the collection of gums, resins and latexes as a means of cash income. Equally, many millions of people in consuming countries make use of these products in their everyday life.

Markets for many of the products have undoubtedly declined over the years and, for some, these markets will never be recovered. This is especially true for some of the latexes. However, for others, there will continue to be a demand, and provided quality and price are right (and, in the case of food gums or resins, legislation continues to permit them) the end-user industries in the consuming countries will wish to continue using them.

The need to maintain quality or, better still, improve it, in order to retain or increase markets cannot be over-emphasized. The quality of the consignment of gum or resin received by an importer depends on a number of factors:

Every effort should therefore be made to improve the collection and post-harvest handling of gums and resins. The use of improved methods of tapping will have the added incentives of increasing yields and minimizing or eliminating damage to the forest resource. Quality control measures should be in place which ensure that there is no mixing of gums from different botanical sources, either accidentally or deliberately by the collector or trader. And excessive handling should be avoided which increases the risk of contamination, including microbial contamination.

In the past especially, but to some extent even now, the wild sources of gums, resins and latexes have been damaged by the methods employed for tapping and by over-exploitation of the resource. The introduction of better tapping techniques is one way of avoiding damage, but the use of cultivated sources can also reduce the pressure on the natural forest, and by improving the accessibility of the trees to the collector can increase the efficiency of collection. Cultivation may be on a large scale (as, for example, with some of the plantations of Acacia senegal in Sudan which are tapped for gum arabic) or in an agroforestry context (as in the case of Shorea javanica in Indonesia which is being grown as a source of damar). Some species of Canarium have the potential for multipurpose use as a source of edible fruits or nuts and elemi resin.

There are good grounds for optimism that despite the changes which have occurred in the markets over the years there will continue to be a demand for gums, resins and latexes (albeit more for some than others) and that there are opportunities for people in the producing countries, providing due attention is given to such aspects as quality control of the product and sustainable management of the resource.
 

COVERAGE AND FORMAT OF THE REPORT

Many thousands of plant species yield gums, resins or latexes, and probably several hundreds are utilized to produce items of trade, either local or international. Of these, the 22 listed in Table 1 are the subject of this report.

All except one enter world trade, and those which do range from large volume gums such as gum arabic - where over 30 000 tonnes were exported from producer countries in 1994 - to small volume resins and latexes, where less than 50 tonnes/year are traded. Mesquite seed gum is not yet produced commercially but has the potential to do so.

Except for tragacanth and asafoetida/galbanum, which come from small shrubby plants, all the products are obtained from trees, although these vary in size from relatively small Acacia to Dyera species up to 50 m or more tall. They have been chosen to illustrate the diversity of the products and their applications, and the different types of forest cover, ecological zones and geographical regions from which they come ? from food additives, flavours and fragrances to pharmaceuticals and industrial applications; from small shrubs or trees of the arid and semi-arid zones of Africa and India to medium-sized trees of the Mediterranean region, and large trees of the Amazonian and Southeast Asian rainforests. The developmental potential of the products discussed ranges from those with high potential such as gum arabic, locust bean and damar to those with very little potential such as dragon's blood and balata.

A standard format has been adopted when discussing each product:

A large number of gums, resins and latexes have inevitably had to be omitted from this report, including some which are traded internationally in significant quantities. A few have been omitted because they have already been the subject of recent publications:


Some have been omitted because they are not forest products. These include (a) seaweed gums, (b) those produced as agricultural crops and (c) some produced commercially by microbial biosynthesis:

(a) Agar
Alginates
Carrageenan

(b) Guar gum from Cyamopsis tetragonoloba
Psyllium gum from Plantago spp.
Guayule latex from Parthenium argentatum
Rubber latex from Hevea brasiliensis

(c) Gellan gum
Xanthan gum

Processed gums such as modified starches and celluloses are excluded. Others have been omitted in order to keep the present report to a reasonable size or because there is insufficient published information to enable an adequate account to be given of the particular gum, resin or latex. These include:

Gums
Cashew from Anacardium occidentale
Ghatti from Anogeissus latifolia
Gum arabic-like gums from Combretum, Albizia and
Leucaena spp.
Gum from Cassia spp. (e.g., C. tora)
Gum from Sesbania spp. (e.g., S. bispinosa)
Semla from Bauhinia retusa
Tamarind from Tamarindus indica

Resins
Accroides from Xanthorrhoea spp.
Gaharu resin-soaked wood from Aquilaria spp.
Gamboge from Garcinia spp.
Guaiacum from Guaiacum spp.
Gumweed from Grindelia camporum
Gurjun balsam from Dipterocarpus kerrii
Kauri from Agathis
Labdanum from Cistus spp.
Lac (shellac) from the lac insect
Sandarac from Tetraclinis and Callitris spp.

Latexes

Chilte from Cnidoscolus spp.

Many other gums, resins and latexes have been the subject of research reports but these are not discussed further here.

REFERENCES

ANDERSON, D.M.W. (1991) Recent changes in toxicological status of permitted food emulsifiers, stabilisers and thickeners. South African Journal of Food Science and Nutrition, 3(2), 25?28.

COPPEN, J.J.W. and HONE, G.A. (1995) Gum Naval Stores: Turpentine and Rosin from Pine Resin. Non-Wood Forest Products series. No. 2. 62 pp. Rome: Food and Agriculture Organization.

GRAY, P.S. and PENNING, W. (1992) Present and future legislation of food hydrocolloids. pp 17?27. In Gums and Stabilisers for the Food Industry, Vol. 6. Proceedings of 6th International Conference, Wrexham, 1992. Oxford: IRL Press.

NAUDE, A. (1994) Food additives '94. Thickeners, the next generation. Chemical Marketing Reporter (27 June), pp SR16 and SR18.

ROBBINS, S.R.J. (1988) Gum arabic. pp 18?33. In A Review of Recent Trends in Selected Markets for Water-Soluble Gums. ODNRI Bulletin No. 2. 108 pp. London: Overseas Development Natural Resources Institute [now Natural Resources Institute, Chatham].
 
 

Table 1. Gums, resins and latexes described in the report
 
 
Gum, resin or latex  Main genera  Family  Main producing regions 
Exudate gums 
Gum arabic  Acacia  Leguminosae  Africa 
Karaya  Sterculia  Sterculiaceae  Asia, Africa 
Tragacanth  Astragalus  Leguminosae  Asia Minor 
Seed gums 
Locust bean  Ceratonia  Leguminosae  Mediterranean 
Mesquite  Prosopis  Leguminosae  Americas, 
Africa, Asia 
Tara  Caesalpinia  Leguminosae  S America 
Hard resins 
Copal  Agathis  Araucariaceae  SE Asia 
Damar  Shorea ,
Hopea, Vatica
Dipterocarp- aceae  SE Asia 
Mastic  Pistacia  Anacardiaceae  Mediterranean 
Dragon's blood  Daemonorops  Palmaceae  SE Asia 
Soft resins/balsams 
Benzoin  Styrax  Styracaceae  SE Asia 
Styrax  Liquidambar  Hamamelidaceae  Asia Minor, 
C America 
Peru/Tolubalsams  Myroxylon  Leguminosae  C/S America 
Copaiba  Copaifera  Leguminosae  S America 
Elemi  Canarium  Burseraceae  SE Asia 
Asafoetida/ 
Galbanum 
Ferula  Umbelliferae  Asia Minor 
Latexes 
Chicle  Manilkara  Sapotaceae  Americas 
Jelutong  Dyera  Apocynaceae  SE Asia 
Sorva  Couma  Apocynaceae  S America 
Gutta percha  Palaquium  Sapotaceae  SE Asia 
Balata  Manilkara  Sapotaceae  S America 
Maçaranduba  Manilkara  Sapotaceae  S America 

 
 

Table 2. Gums and resinsa (excluding gum arabic): imports into the
European Community, and sources, 1988-93
(tonnes)
 
 
1988 
1989 
1990 
1991 
1992 
1993 
Total 
15754 
21238 
22774 
25161 
22718 
13521 
Of which from 
Brazil 
1056 
3959 
8197 
10041 
7431 
1427 
Indonesia 
2599 
3033 
2680 
2567 
3609 
3239 
India 
1694 
2108 
690 
796 
1111 
1352 
Senegal 
1182 
1735 
1824 
1477 
1329 
919 
Iran 
956 
969 
779 
910 
689 
808 
Singapore 
863 
737 
1186 
813 
855 
630 
Germany 
827 
683 
711 
649 
912 
801 
France 
561 
797 
894 
1041 
676 
614 
UK 
409 
504 
694 
527 
676 
522 
China,P.Rep. Of 
285 
457 
202 
2010 
1871 
33 
Nigeria 
359 
698 
503 
294 
201 
381 
Philippines 
207 
259 
515 
143 
177 
291 
Mali 
104 
446 
549 
560 
484 
197 
Sudan 
343 
318 
234 
433 
317 
279 
Spain 
197 
227 
391 
320 
438 
101 
Portugal 
463 
122
143 
548 
59 
88 
Ethiopia 
220 
231 
285 
139 
131 
62 
Somalia 
108 
167 
121 
151 
237 
202 
South Africa 
1288 
1478 
363 
Netherlands 
283 
262 
87 
226 
307 
267 
USA 
232 
271 
331 
186 
114 
115 
Australia 
101 
111 
152 
186 
134 
209 
Turkey 
114 
242 
55 
33 
25 
Albania 
18 
185 
257 
72 
277 
Others 
1285 
1239 
1188 
854 
862 
694 

Source: Eurostat
Note:
a "Natural gums, resins, gum-resins and balsams".
b A significant proportion of Brazilian exports is believed to be crude pine
resin imported into Portugal.
 
 

Table 3. Gums, resins and latexesa: exports from Indonesia, by type, 1988-93
(tonnes; US$ millions)
 
 
 
1988 
1989 
1990 
1991 
1992 
1993 
Total 
17114 
33236 
40531 
41270 
35052 
41961 
FOB value 
9.8 
19.6 
24.8 
23.4 
22.1 
24.9 
Of which :
Damarb
10343 
11372 
10878 
12573 
10175 
13285 
Jelutongc
2358 
5373 
6495 
3700
2712 
1182 
Copal 
2485 
1811 
1766 
1880 
1863 
1886 
Gum arabicd
2937 
2050 
2405 
1988 
361 
Benzoine
1157 
975 
884 
1126 
806 
824 
Lac 
411 
227 
703 
221 
245 
311 
Gutta percha 
75 
156 
316 
366 
241 
Dragon's blood 
26 
59 
71 
87 
47 
25 
Gahuru 
39 
44 
47 
181 
204 
"Other gum"f
107 
9947 
16557 
18602 
16454 
23255 
"Other resin" 
129 
391 
927 
311 
177 
387 
Others 
95 
30 
38 

Source: National statistics

Notes:

a Excludes agar-agar (a seaweed gum) and "Resin pine"
(= pine rosin, a processed product of crude pine resin).

b Includes "Damar", "Resin batu" and "Resin mata kucing" (see section on DAMAR).

c Includes raw, pressed, refined, and other.

d Very improbable that this is genuine gum arabic.

e Classified as "Frankincense" (see footnote to Table 23).

f From 1989, it is probable that a large proportion of this is crude pine resin.
 

Table 4. Gums and resins: exports from India, by type, 1987/88-1993/94a
(tonnes)
 
 
87/88 
88/89 
89/90 
90/91 
91/92 
92/93 
93/94 
Total 
8013 
9674 
7818 
8257 
7299 
7124 
8513 
Of which :
Lacb
5038 
7157 
5169 
6958 
5673 
4989 
5935 
Karaya 
2001 
1831 
1628 
599 
574 
843 
1443 
Asafoetida 
140 
144 
149 
130 
164 
231 
205 
Olibanum 
167 
81 
19 
75 
70 
113 
66 
Gum arabic 
30 
30 
80 
83 
Asian gum 
23 
41 
37 
12 
19 
"Other natural gums" 
484 
331 
683 
374 
567 
660 
592 
"Other gum resins" 
102 
42 
61 
51 
214 
97 
116 
"Other resins" 
21 
30 
66 
18 
87 
45 
Others 
31 
14 
18 

Source: National statistics

Notes: a Year runs April-March

b Includes shellac, seedlac, button and garnet lac, stick lac,
dewaxed and decolourised lac, bleached lac, and other lacs including
lac dye.
 
 

Table 5. Gums and resinsa: exports from the People's Republic of China,
and destinations, 1990-92
(tonnes)
 
 
 
1990 
1991 
1992 
Total 
8701 
340 
2755 
Of wich to: 
Hong Kong 
6575 
212 
1497 
India 
2105 
Spain 
350 
Viet Nam 
305 
Indonesia 
29 
55 
Thailand 
15 
52 
Singapore 
59 
Nigeria 
72 
Russia 
50 
USA 
12 
12 
Japan 
22 
Iran 
14 

Source: China's Customs Statistics Yearbook
Note: a "Natural gums, resins, and balsams excluding lac and gum arabic"

___________________________________
2/ Annual world production of pine resin is almost one million tonnes, making it by far the most important natural resin of commerce. It is obtained by tapping pine trees and is used as a source of turpentine and rosin, but it has been reviewed in detail elsewhere (COPPEN and HONE, 1995) and is not discussed in this report.

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