Tropical starches: a grainy issue

Tropical starches have served as traditional staple crops for people throughout the world's hot and humid regions and yet, until recently, the potential for value-addition to starches grown in developing countries was relatively limited. Maize, wheat and potato dominate lucrative world markets for starches in food and non-food industries but there are other sources of starch which could be developed to reduce developing countries reliance on starch imports as well as providing products for export.

Edible canna (Canna edulis Ker-Gawler), for instance, is a root crop which is outstandingly versatile and robust. However, more than three hours is required to soften the rhizome tissue and in its native Andean range, as well as in other parts of the developing world, the use of canna for direct consumption is about to disappear. And yet, in Vietnam and southern China, there has been a new appreciation of canna as a source for starch in the manufacture of transparent noodles, a luxury food widely eaten across Asia. Canna has the largest starch grains known and is functionally similar to mungbean starch, the traditional constituent for transparent noodles but it is less expensive to produce. However, canna starch does not currently meet the quality standards required by most industrial-grade starch users although CIP scientists believe that canna starch could replace potato starch in other types of Asian noodles and certain bakery goods.

In the Shandong and Sichuan provinces of China, transparent noodles are made from starch extracted from sweet potatoes, an important crop in China's small farming systems. On the densely populated island of Sichuan, in particular, increased use of sweet potatoes for starch offers real potential for rural income generation in those areas where this crop is grown, and where the need for poverty alleviation is acute. CIP, working with the Sichuan Academy of Agricultural Sciences, has been evaluating the potential for the further development of small-medium scale sweet potato starch enterprises and significant progress has already been achieved in upgrading existing processing technology.

For farmers in upland or mountainous areas of Vietnam, where only a small proportion of the land is suitable for intensive rice production, it is cassava grown for animal feed or starch production that often represents farmers' best hope for raising their incomes. More than 20,000 rural households in 1998 were employed in starch processing and, with the addition of traditional farming activities, the total income of these households was more than twice the average rural per capita income. However, although growth potential is considerable, it may be limited by serious constraints relating to sustainability and quality with the most serious environmental byproduct being water pollution. In addition, says Francesco Goletti of IFPRI who has been working with the Vietnamese, the export of starch would require quality improvement in line with international standards.

Despite these successes with tropical starches, a recent study by FAO's AGSI concludes that there is an increased need for further research and development on product characteristics that make processing easier if value-added starches are to become competitive and establish a significant presence on world markets. This research would also pay dividends because the export of value-added starches would not only boost the prosperity of developing countries but as their economies grow, so will the domestic demand for high quality, highly functional, value-added starches.

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