INFLUENCES OF POLYOLS ON THERMAL AND DYNAMIC VISCOELASTIC PROPERTIES OF RICE STARCHES DURING GELATINIZATION

The thermal and dynamic viscoelastic characteristics of indica (KSS7) and japonica (TNu67) rice starches (starch:water = 1:2) during gelatin ization have been investigated in polyol solutions, with DSC and dynam ic rheometry. The results indicate that the increments of some critica l temperatures (T-o, T-p, T-G' and T-G'max) in the thermograms and rhe ograms of rice starches are correlated well with the dynamic hydration number of polyol added. This firmly implies the importance of polyol- water interaction in delaying the initial gelatinization. Polyol-starc h interactions appear to be different for low-MW polyol and maltodextr in (DE = 8 similar to 14) studied. As suggested by the changes in Delt a H, tan delta and G'(95) values, the action from the plasticization o f polyol presumably occurs during final gelatinization. These interact ions and the plasticization of water and polyol cosolvents depend cons iderably on the granular structure of starch.