Standard maize starch was hydrothermally treated at residual moisture content (similar to 12%) by instantaneous controlled pressure drop for various pressure levels and processing times. In order to examine the homogeneity of the starch treatment, three thicknesses (1.5, 1 and 0.5 cm) were tested at 3 bar of steam pressure. For the three thicknesses, the temperature and the moisture content of starch were measured during the treatment at the bottom and the surface. The results showed an absence of gradient of temperature and moisture content only for a thickness of 0.5 cm. Gelatinization transition temperatures (T-o, T-p) increased after hydrothermal modifications. The change in the gelatinization temperature range was observed after DIC treatment when pressure level or processing time increased. For a high pressure (>= 4 bar) associated with low processing time (2 min) a total gelatinization of starch was observed. It also occurs when the processing time is important (similar to 15 min) and pressure lower than 4 bar. (c) 2005 Elsevier Ltd. All rights reserved.