The structural evolution of a maize flour was followed by means of oscillatory shear measurements during heating at a rate of 10 degreesC/ min in presence of water. These measurements were performed in a special plate and plate vessel designed to prevent moisture loss. The phenomena of gelatinization and gelation were clearly identified and their connection with the moisture content also demonstrated. Moreover, the complex mechanisms involved in gelatinization and gelation in native starch were separated. Softening of the amylose zones, exchange of water and amylose within the starch granules followed by amylopectin melting leads to the gelation of starch.