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Kernel Microstructure of Latin American Races of Maize and Their Thermal and Rheological Properties

¹Universidad Autónoma de Querétaro, Centro Universitario, Cerro de las Campanas S/N, Querétaro, Querétaro, México, CP 76010. ²Centro de Investigaciones y Estudios Avanzados del IPN, Unidad Querétaro, Libramiento Norponiente No. 2000 Fraccionamiento Real de Juriquilla, Querétaro, México, CP 76230. ³Corresponding author. E-mail: jfigueroa@qro.cinvestav.mx ⁴Centro Internacional de Mejoramiento de Maíz y Trigo, Carretera México-Veracruz Km 45 El Batán, Texcoco, Estado de México, México, CP 56130. ⁵Universidad Autónoma Agraria Antonio Narro, Buenavista, Saltillo, Coahuila, México CP 25315.

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.