Study of DIC hydrothermal treatment effect on rheological properties of standard maize (SMS), waxy maize (WMS), wheat (WTS) and potato (PTS) starches

Standard maize (SMS), waxy maize (WMS), wheat (WTS) and potato (PTS) starches were hydrothermally treated by Instantaneous Controlled Pressure Drop (DIC) process at different pressure levels (1, 2 and 3 bar) corresponding to the temperatures of 100, 122 and 136 °C, respectively. The rheological properties and particle size of treated starches under various conditions were compared to the native ones. The results showed for all starches, except for WTS, a reduction of the consistency coefficient and the yield stress (τ0) with increased intensity of the hydrothermal treatment conditions. Furthermore, τ0 vanished for severe treatment conditions. The DIC treatment yielded an increased fluidity and a loss of the conservative modulus of the pastes, as a result of partial gelatinization of starch granules. The extent of the observed effect depended on the botanical origin. Wheat starch exhibited a different behaviour: the consistency coefficient and the conservative modulus being higher for DIC treated starch except for the most severe conditions.