Resumen de Influence of fructose and sucrose on small and large seformation rheological behaviur of heated amioca starch
M.A. Rao, K.S. Youn, V.M. Acquarone, D.B. Genovese
Effect of sucrose or fructose on the rheological behaviour of gelatinized 5% w/w amioca starch dispersions (GSDs), was studied by small and large deformation rheological techniques. Storage (G') and loss (G'') moduli as a function of angular frequency (omega), and shear stress (sigma) as a function of shear rate (gamma) data were obtained on GSDs with: 0, 30 and 60% w/w sugars. Magnitudes of Herschel-Bulkley yield stress (sigma 0-HB) were determined from sigma-gamma data. Using the vane method, the static yield stress (sigma 0s), the dynamic yield stress (sigma 0d) and the shear modulus (G) were determined. Effect of pasting temperature and ageing time were also studied by the vane method. Addition of sugars produced an increase in all rheological parameters except sigma 0d, suggesting that sugars increased the strength of the internal bonds or cohesiveness of the GSDs; in general, fructose was slightly more effective than sucrose. Equivalent parameters: G' and G, and sigma 0s and sigma 0s showed good agreement. Decreasing the heating temperature increased G. GSDs with fructose showed a clear increase in sigma 0s and G with ageing time. (A)
