EFFECTS OF HYDROTHERMAL TREATMENTS ON THE RHEOLOGICAL PROPERTIES OF POTATO STARCH

Potato starch was hydrothermally treated at moisture levels ranging fr om 20 to 40% and at temperatures 3% below the gelatinization peak temp eratures (in K). The treatments had a great impact on the rheological behavior as studied with a rapid visco analyzer (RVA) and dynamic visc oelastic measurements. The extent of the observed effects did not only depend on the specific treatment but also on the starch concentration s investigated (3.0, 6.6, and 20.0%). For the dynamic measurements, th e gel storage moduli were related td swelling power and close packing concentration. The increase in onset temperature of viscosity developm ent and the decrease in peak viscosity observed with RVA as a conseque nce of hydrothermal treatments, were also attributed to the decreases in swelling power and solubility. (C) 1997 Elsevier Science Ltd.