2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

Sugar is the main additive in cereal products and affects the melt viscosity of starch, thus contributing to the final product quality. The purpose of this work is to understand under controlled conditions of shear and temperature, how sugar affects starch conversion and melt elasticity and also to determine the relationship between the latter two factors. The flow behavior of wheat semolina and maize grits with the same particle size distribution were studied in the presence of three levels of sucrose 0, 10 and 20 percentage using a twin barrel capillary rheometer fitted with 2 mm die. Four temperatures : 90, 100, 110 and 120°C and two wall shear rates: 10(1/s) and 500(1/s) were investigated. The sectional and longitudinal expansion of the extrudate from the capillary die was measured. Starch conversion was monitored by X-ray diffraction, dynamic scanning calorimeter (DSC) and Rapid Visco Analysis. The flow behavior of maize and wheat was influenced by sucrose content. The viscosity of the wheat melt was found to be considerably lower than maize. Although the addition of sucrose reduced the viscosity of both systems, it did not have a significant influence on starch conversion. An understanding of the role of sugar during conventional and extrusion cooking of cereal products will allow prediction and hence improvement of final product quality.