Effect of tapioca starch addition on rheological, thermal, and gelling properties of rice starch

The rheological, thermal, and gelling properties of blends of rice starch (RS) with tapioca starch (TS) at different RS/TS ratios (10/0, 9/1, 8/2, 7/3, 6/4, and 5/5) were examined. Steady and dynamic shear rheological tests indicated that the consistency index (K) and yield stress (sigma(oc)) of the RS TS blends increased with an increase in the mixing ratio of TS while the dynamic moduli (G' and G '') values decreased. Tan delta (ratio of G ''/G') values of all the blends were higher than that of RS, indicating that there is a more pronounced synergistic effect on the viscous properties of RS in the presence of TS. DSC studies found that the transition temperatures and enthalpies of gelatinization of the blends appeared to be greatly influenced by the addition of TS. The blend gels showed higher gel strength and also better freeze-thaw stability with a significant decrease in syneresis (%) in higher ratios of TS. In general, these results suggest that in the RS-TS blend systems, the addition of TS modified the rheological, thermal, and gelling properties of RS, and that these modifications were dependent on the mixing ratio of TS as well as the physical properties of the two component starches. (C) 2015 Elsevier Ltd. All rights reserved.