Comparative study of maize cultivars 30 days after pollination (30 DAP): characterization of starch

Characterization of starch was comparatively studied in five maize cultivars, i.e., Maya Normal, Nutrimaiz, two hybrids (L90 x L78, L90 x L41) and Supersweet (SRR "Duro"), 30 days after pollination (30 DAP). Amylose content was found to be higher in the Maya Normal starch (31.3%) and lower (23 to 27%) in the genetically-modified cultivars. The absolute density of the isolated starches did not show significant differences among cultivars. Solubility and swelling studies suggested the presence of more homogenous forces maintaining the granular matrix on the starch from Maya Normal in relation to the other maize cultivars. The starch from the genetically-modified cultivars had a reduced solubility in dimethylsulfoxide and lower values for the gelatinization temperature range, in comparison to the Maya Normal. Information from the Brabender amylogram indicated greater resistance of the gelatinized maize starches to granule breakdown by mechanical stirring, in the new genotypes, resembling those starches modified by cross-linking.