Tara (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
Tara gum constitutes the clean, ground endosperm of the seeds of Caesalpinia spinosa. It is a white to yellowish white powder and consists chiefly of galactomannan-type polysaccharides. The ratio of galactose to mannose in tara gum is 1:3 (compared to 1:4 in locust bean gum and 1:2 in guar gum).
Tara gum is used as a thickening agent and stabilizer in a number of food applications. A solution of it is less viscous than a guar gum solution of the same concentration, but more viscous than a solution of locust bean gum. Blends of tara with modified and unmodified starches can be produced which have enhanced stabilization and emulsification properties, and these are used to advantage in the preparation of convenience foods.
WORLD SUPPLY AND DEMAND TRENDS
Markets
Tara gum is a relative newcomer to international trade and developmental work aimed at exploring the range of applications for which it might be suitable is still being undertaken.
Peru is the major exporter of powdered tara pods, which are used as a source of tannin (see PRODUCTS OTHER THAN GUM below), but data on tara gum are not readily available. A recent estimate of 1 000 tonnes annually was given by WIELINGA (1990) for total world production of tara gum, but no indication was given either of the trend or of the main markets.
Supply sources
Peru, as stated above, is believed to be the biggest (and, perhaps, the sole) exporter of tara gum. Bolivia and Ecuador are known to harvest small quantities of tara and there may be some production, also, in Chile and Colombia.
Quality and prices
The highest grades of tara gum are white and free from specks of husk and germ.
An FAO specification exists for tara gum which specifies upper limits on parameters such as moisture, ash, acid-insoluble matter, arsenic, heavy metals and protein.
Prices for tara gum are not known.
PLANT SOURCES
Botanical/common names
Family Leguminosae (Caesalpinioideae): Caesalpinia spinosa L. - Tara, huarango
*Accepted name : Tara spinosa.
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Description and distribution
Caesalpinia spinosa is a shrub or tree, with spreading, grey-barked leafy branches. The pods are flat, about 10 cm long and 2.5 cm wide, containing 4-7 large round seeds; the seeds are black when mature.
The tree is native to the Cordillera region of Bolivia, Peru and northern Chile and also occurs in Ecuador, Colombia, Venezuela and Cuba. It is also cultivated in most of these countries. It has been introduced to other parts of the world, including North Africa (notably Morocco) and East Africa.
It grows in ecological zones ranging from Warm Temperate Dry through Tropical Very Dry to Tropical Wet forest zones.
COLLECTION/PRIMARY PROCESSING
No easily accessible information is available on the harvesting of tara or on yields of seed to be expected from the tree. Most seed is harvested from wild trees although these are subjected to simple pruning operations.
The physical composition of tara seed (by weight) is approximately:
| Germ | 40% |
| Hull | 38% |
| Endosperm | 22% |
Yields of tara gum (endosperm) from the seed are therefore relatively small (22%), and less than that for the two other principal seed gums, locust bean (40-50%) and guar (ca 35%).
Like locust bean, the hull of tara is tough and hard, and special processes have to be used to remove the hull before separating the endosperm and germ. Acid treatment or roasting processes (as described for locust bean) are used to obtain the endosperm.
VALUE-ADDED PROCESSING
Like guar gum, further processing entails blending tara with other gums or chemically modifying it to produce the range of functional properties that are sought. This further processing is capital-intensive and is only carried out on a large scale by companies who process other gums in a similar manner.
PRODUCTS OTHER THAN GUM
Once separated from the hull and endosperm, it should be possible to use the germ of the seed as a source of protein, perhaps in animal feeds. However, it is not known whether this occurs in practice.
Tara pods are rich in tannin and are a regular item of trade in Peru for tanning purposes. The tannin is used extensively in South America and Morocco for tanning sheep and goat skins, and produces a good quality, light-coloured leather. Peruvian exports of powdered tara for tanning purposes averaged just over 5 000 tormes/year during 1990-93.
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Caesalpinia spinosa is sometimes grown as a live fence in Peru for keeping out animals.
DEVELOPMENTAL POTENTIAL
There is very little documented information available to know to what extent tara has been investigated as a dual purpose seed crop. Since the pods are utilized for tannin extraction purposes it is logical to think, also, in terms of gum production from the seeds. In this way, further economic value can be derived from a single harvested product (i.e., pods containing the seeds).
The opportunities for increasing production of tara depend very much on the markets for both tara gum and the tannins derived from the pods. If both markets are supplied from present production, then a disproportionate upturn in one market will, if met by increased production, cause an oversupply in the other. The greatest need in ascertaining the developmental potential of tara is therefore to investigate the markets for the seed (as a source of gum) and the pods (as a source of tannin).
SELECTED BIBLIOGRAPHY
- BENK, E. (1977) [Tara kernel meal. A new thickening, binding and stabilizing agent] (in German). Riechstoffe, Aromen, Kosmetica, 27(10), 275-276.
- DUKE, J.A. (1981) Caesalpinia spinosa. pp 32-33. In Handbook of Legumes of World Economic Importance. 345 pp. New York: Plenum Press.
- FAO (1992) Tara gum [published in FAO Food and Nutrition Paper 37, 1986]. pp 1475-1476. In Compendium of Food Additive Specifications. FAO Food and Nutrition Paper 52 (Joint FAO/WHO Expert Committee on Food Additives. Combined Specifications from 1st through the 37th Meetings, 1956-1990). Rome: Food and Agriculture Organization.
- JUD, B. and LOESSL, U. (1986) [Tara gum - a thickening agent with a future] (in German). Internationale Zeitschrift fur Lebensmittel Technologie und Verfahrenstechnik, 37(1), 28-30.
- ROJAS-PAJARES, H. (1991) [Determination of Parameters for Obtaining Tara Seed Gum (Caesalpinia tinctorea) by Aqueous Method and Dried by Spray Drying] (in Spanish). 94 pp. Lima, Peru: Universidade Nacional Agraria La Molina (Escuela de Post-Grado, Especialidad de Tecnologia de Alimentos).
- RUIZ, C.A.B. (1994) Country paper: Peru. Paper presented at the FAO Expert Consultation Meeting on Non-Wood Forest Products, Santiago, Chile, 4-8 July.
- WIELINGA, W.C. (1990) Production and applications of seed gums. pp 383-403. In Gums and Stabilisers for the Food Industry, Vol. 5. Proceedings of 5th International Conference, Wrexham, July, 1989. Oxford: IRL Press.
