Changes

Chicle is the coagulated latex obtained from ''Manilkara zapota'', and is produced on acommercial scale in Mexico and certain parts of Central America. Chicle is to bedistinguished from sapote gum, the hard, gummy material which forms slowly over thewound made in the tree to obtain the latex, after the latter has ceased to flow. Sapote gumwas once used in Peru as a sizing agent for cloth, and as a glue, but it does not enter world trade and is not considered further here.

Although it has had miscellaneous minor uses as a gutta percha substitute, chicle's economicimportance has arisen from its use in the manufacture of chewing gum, where it imparts the"chewing" properties to the product. An inferior, little-used "chicle"-type of gum is crowngum.

At one time, chewing gum base consisted almost entirely of natural "gums", of which theprincipal one was chicle. The most important of the other natural gums was jelutong,although smaller quantities of sorva and maçaranduba have also been used. Nowadays, withthe advent of cheaper, synthetic resins with suitable properties, demand for the natural gums for use in chewing gum has declined.

The United States chewing gum industry was traditionally the major consumer of chicle butas they have moved towards using a greater proportion of synthetic gums, imports of chiclehave fallen, and the Far East has become the major market, particularly Japan. In 1930, atthe peak of production, over 6 000 tonnes of chicle were imported into the United States.In the period 1963-66, American imports of chicle from Mexico, the leading producer,averaged just over 1 000 tonnes/year. In the three years 1988-90, exports of chicle to theUnited States from Mexico (Table 30) averaged 10 tonnes.

In Europe, at least as far as Mexican exports of chicle are concerned (Table 30), Italy hasbeen the major importer. Total annual imports into Italy may amount to 100-200 tonnes.

Mexico is believed to be the biggest producer of chicle, although if the disaggregation ofimported chicle and gutta-type products into Japan - and shown in Table 32 - is correct,

Guatemala, which has been a significant producer in the past, may recently have surpassedMexico: estimated imports from the two countries for the period 1988-94 averagedapproximately 400 tonnes (Guatemala) and 370 tonnes (Mexico) each year. Exports of chiclefrom Mexico for 1988-90 are shown in Table 30.

Recent quality and price information on chicle is not available. General requirements ofnatural masticatory substances, including chicle, are specified in the Food Chemicals Codexof the United States and these detail limits on arsenic, lead and heavy metals.

Details of tapping methods used on plantation-grown trees are not known, but in the wild,methods have probably changed little from the early days of production. Contemporarydescriptions given by BOLT (1961) are essentially the same as earlier ones by EGLER (1947).

Further processing (before mixing with other ingredients to form a chewing gum base) entailsdrying, melting and centrifuging to remove extraneous matter.

The economic viability of chicle production from cultivated sources depends on the continuedmarket for chicle as a natural chewing gum ingredient, as well as production factors such aslabour costs. If the market can be maintained and production costs can be held stable, thensome increase in the area under cultivation can be justified. Providing the price of

Efforts have been made to extract chicle from the leaves and unripe fruits of the tree, butyields have been too poor to make such production economic. Research should focus onways of increasing yields of latex from the trunk, either by using improved planting stock or through use of better tapping methods:*Populations of trees throughout the natural range of ''Manilkara zapota'' should be screened to determine the intrinsic (genetic) variability in latex yield between and withinprovenances, with a view to identifying high-yielding trees.*The development of improved tapping methods should include an investigation of thepossible benefits of using chemical stimulants to increase yields of latex; such methodshave been used to improve rubber yields in ''Hevea''.

*ANON. (1967) A note on the market for chicle. 3 pp. Unpublished memorandum of the TropicalProducts Institute, London [now Natural Resources Institute, Chatham].

*TESSIER, A.M., NOLOT, P. and DELAVEAU, P. (1976) [Critical review of the latexes ofApocynaceae, Euphorbiaceae, Moraceae and Sapotaceae used in masticatories] (in French). ''Plantes Médicinales et Phytothérapie'', '''10''', 203-212.*TESSIER, A.M., NOLOT, P. and DELAVEAU, P. (1977) [Modern masticatories] (in French).''Médecine et Nutrition'', '''13'''(3), 171-199.