Depolymerisation of cassava starch

A factor in the use of native cassava starch for commercial food production is its variability. Agronomic factors and processing protocols alter the performance of starch in food products, Work carried out at the University of Nottingham has indicated that cassava is particularly susceptible tn starch conversion when being extruded Also cassava seems particularly liable to undergo oxidative reductive depolymerisation compared with other tuber and cereal starches. Low addition rates of substances that interact with oxygen to produce free radicals cause changes in the behaviour of starches. Agents that seem to have an effect on cassava include: sulfite, ascorbic acid and glutathione. The actual level of these compounds is important as maximum degradation is caused at a specific addition rate. Changes caused by the inclusion of the redox agents can be stopped or at least reduced by the use of the free radical terminator, propyl gallate. The inclusion of sulfite with cassava starch has been shown to alter the gelatinisation properties of the granules, the viscosity of pastes and the average molecular weight of amylose or amylopectin or of both polysaccharides. (C) 1999 Elsevier Science Ltd. All rights reserved.