Effect of sucrose addition on rheological and thermal properties of rice starch-gum mixtures

The effect of sucrose at different concentrations (0, 10, 20, and 30% w/w) on rheological and thermal properties of 5% (w/w) rice starch (RS) pastes mixed with guar gum (GG) and xanthan gum (XG) was examined. The flow behavior index (n) values of RS-gum mixtures in the presence of sucrose were higher than those of the control (0% sucrose), whereas their K and σ_oc values were lower. The RS-XG-sucrose mixtures showed much higher dynamic moduli values than the control, while the RS-GG-sucrose mixtures, except for the 30% sucrose concentration, showed lower values, indicating that the viscoelastic properties of RS-XG mixtures were greatly affected by the addition of sucrose. In general, differential scanning calorimetry studies showed that the presence of sucrose resulted in an increase in the gelatinization temperatures and a decrease in gelatinization enthalpy. These results could facilitate the development of RS-based products with improved thermal and rheological properties.