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The vitreous and floury endosperms have regional distributions in maize kernels, and influence their qualities and applications. In this study, the whole transverse and longitudinal sections of maize mature dent, flint, and pop kernels were observed to reveal and compare the morphological characteristics of cell, starch, and protein in different regions of endosperm. The shape and size of cells had significant differences in different regions of dent and flint maize endosperms, but had no relationship with vitreous and floury texture. Popcorn had homogeneously polygonal cells in whole endosperm. The vitreous endosperm in middle and central regions of kernel had polygonal starch granules with large size and that close to aleurone cells had spherical granules with small size, but the floury endosperm had only spherical granules with different sizes. The shape and size of starch granules did not directly determine the texture of vitreous and floury endosperm. The storage protein was distributed regionally in endosperm, and its content and spatial distribution was related with vitreous endosperm. The above results not only enriched our knowledge of vitreous and floury endosperms of maize, but also provided some information for quality breeding and applications of maize kernels with different vitreousness. • The whole sections were prepared in maize mature dent, flint and pop kernels. • Cell, starch and protein in different regions of endosperm were viewed and compared. • The shape and size of cells had no relationship with vitreous and floury endosperm. • Starch granules did not determine the texture of vitreous and floury endosperm. • The content and spatial distribution of protein was related with vitreous endosperm. [ABSTRACT FROM AUTHOR]

Abstract: The effects of endosperm vitreousness, cooking time and temperature on sorghum and maize starch digestion in vitro were studied using floury and vitreous endosperm flours. Starch digestion was significantly higher in floury sorghum endosperm than vitreous endosperm, but similar floury and vitreous endosperm of maize. Cooking with 2-mercaptoethanol increased starch digestion in both sorghum and maize, but more with sorghum, and more with vitreous endosperm flours. Increasing cooking time progressively reduced starch digestion in vitreous sorghum endosperm but improved digestibility in the other flours. Pressure-cooking increased starch digestion in all flours, but markedly more in vitreous sorghum flour; probably through physical disruption of the protein matrix enveloping the starch. Irrespective of vitreousness or cooking condition, the alpha-amylase kinetic constant (k) for both sorghum and maize flours remained similar, indicating that differences in their starch digestion were due to factors extrinsic to the starches. SDS-PAGE indicated that the higher proportion of disulphide bond-cross-linked prolamin proteins and more extensive polymerisation of the prolamins on cooking, resulting in polymers of M r>100k, were responsible for the lower starch digestibility of the vitreous sorghum endosperm flour. [Copyright &y& Elsevier]

Popcorn is a healthy snack suggested by nutritionists. However, some countries in Europe, Asia, and South America have evaluated the use of sorghum as a popped cereal. Therefore, this study aims to evaluate the content of corneous and floury endosperm of sorghum and its influence in the popped sorghum quality. Five red varieties and three white varieties were evaluated. The physical and microstructural characteristics of the raw varieties were evaluated. The correlation matrix showed that physical properties such as the pericarp thickness, the hectoliter weight, and the type of endosperm are crucial to obtain popped sorghum. A high percentage of corneous endosperm and the size distribution of starch granules in the floury endosperm determine the popping ability of sorghum. The analysis of the principal components showed that the Paloma variety was the most suitable to obtain popped sorghum. Image 1 • Vitreous and floury endosperm affects the popping characteristics in sorghum. • Size and distribution of starch granules in the floury endosperm affect the popped sorghum. • Pericarp thickness of kernel affects the expansion volume of the popped sorghum. • The vitreous/floury endosperms ratio affects the sorghum popping characteristics. • Paloma White variety sorghum showed the best popping yield and popping quality. [ABSTRACT FROM AUTHOR]