Kernel microstructure of Latin American races of maize and their thermal and rheological properties

ABSTRACT Seventy-one races of maize representing races from Latin America were analyzed for microstructural features such as the degree of compaction of the endosperm cell bodies, starch granule size and morphology, and hard-soft endosperm relationship. Flours were analyzed using rapid visco analysis and differential scanning calorimetry. Compaction grade was the most important microstructural feature of the maize kernels that related to thermal and rheological properties. Highly compact kernels developed low peak and final viscosities; small, polygonal starch granules; and required more time and higher temperature to gelatinize. The opposite was the case for less compact kernels. This indicates that the characteristic protein matrix of highly compact kernels represents a physical barrier to water migration into the granules, retarding the gelatinization process.