Rheological, thermal, and gelling properties of azuki bean starch with sucrose

Abstract

Rheological, thermal, and gelling properties of 5% (w/w) Korean azuki bean starch (ABS)-sucrose mixtures at different sucrose concentrations (0, 10, 20, and 30% w/w) were investigated. Flow properties of ABS-sucrose mixtures were determined from rheological parameters for power law and Casson flow models. All mixture pastes exhibited a pseudoplastic shear-thinning characteristic (n = 0.30-0.34) with yield stress. Consistency index (K), apparent viscosity (ha, 50), and Casson yield stress (sigma(oc)) values decreased with an increase in sucrose concentration. Dynamic moduli (G' and G '') values of ABS-sucrose mixtures increased with increasing sucrose concentration, indicating that their viscoelastic properties were greatly affected by the addition of sucrose. The addition of sucrose had little impact on tan delta (ratio of G ''/G') values. Differential scanning calorimetry of ABS-sucrose mixtures showed an increase in the onset (T-o), peak (T-p), and conclusion (T-c) temperatures of gelatinization and a decrease in the enthalpy (Delta H) of gelatinization with a corresponding increase in sucrose concentration. The ABS-sucrose mixture gels showed much lower gel strength values compared to the control (0% sucrose). In general, these results suggest that the presence of sucrose in ABS modifies physical and rheological properties, depending on the sucrose concentration. In addition, these results could facilitate the development of sweetened ABS-based products with improved physical and rheological properties.