Cassava and starch

Cassava is one of the most important commercial crops in Thailand. It is exported mainly to Europe in the form of chips for animal feed. The starch produced from cassava has wider utilization in both food and non-food applications. Industrial utilization of cassava starch has now expanded from being primarily used in paper, textile and plywood industries to the production of biofuel and biodegradable polymers. There are currently over 70 factories producing around 2 million tons of starch per annum. For the domestic market, the largest proportions of native starch go to the industrial production of food flavor enhancers, such as monosodium glutamate, lactic acid and amino acid production for feed supplement, such as lysine.

The main aim of cassava variety improvement in Thailand is to enhance starch yield. Other selection criteria for variety improvement include early harvest time, starch quality, root shape, white flesh and tolerance to pest and diseases. Improvements achieved through conventional hybridization already include nine new varieties with highly desirable characteristics that have been released for industrial use. Current research focuses on two important aspects of starch biosynthesis in cassava; the sucrose partitioning pathway and the biosynthesis of starch granules in the roots. To gain a better understanding of the starch biosynthesis in cassava, identification and extensive expression analyses are being carried out at the molecular level, looking at the enzymes involved in the starch biosynthesis in different cassava cultivars with varying storage starch levels.

Basic studies of cassava starch structure, as related to its functions, also offer more opportunities for researchers to develop industrial applications using cassava starch. The Cassava and Starch Technology Unit, a specialized BIOTEC laboratory established in 1995 at Kasetsart University, has been investigating the physicochemical properties of cassava. In addition, BIOTEC and the Nara Research Institute of Science and Technology in Japan have been collaborating to establish a cassava EST collection for transcription profiling of the cassava genes. Based on this technology a broad spectrum of genes, with many being novel, involved in starch biosynthesis control can be discovered from these studies.