Physical Properties and Microstructural Changes during Soaking of Individual Corn and Quinoa Breakfast Flakes

Authors

  • Wenceslao T. Medina,

    1. Authors Medina and Aguilera are with Dept. of Chemical and Bioprocesses Engineering, Pontificia Univ. Católica de Chile, P.O. Box 306, Santiago, Chile. Author de la Llera is with School of Engineering and Applied Sciences, Faculty of Arts and Sciences, Harvard Univ., 29 Oxford St., Cambridge, MA 02138, U.S.A. Author Condori is with El Altiplano SAC Co., Taparachi Industrial Park D-15, Juliaca, San Román, Puno-Peru. Author Medina is also with School of Agroindustries, Faculty of Agrarian Sciences, Univ. Nacional del Altiplano de Puno, P.O. Box 291, Puno-Peru. Direct inquiries to author Medina (E-mail: wtmedina@ing.puc.cl).
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  • Andrés A. de la Llera,

    1. Authors Medina and Aguilera are with Dept. of Chemical and Bioprocesses Engineering, Pontificia Univ. Católica de Chile, P.O. Box 306, Santiago, Chile. Author de la Llera is with School of Engineering and Applied Sciences, Faculty of Arts and Sciences, Harvard Univ., 29 Oxford St., Cambridge, MA 02138, U.S.A. Author Condori is with El Altiplano SAC Co., Taparachi Industrial Park D-15, Juliaca, San Román, Puno-Peru. Author Medina is also with School of Agroindustries, Faculty of Agrarian Sciences, Univ. Nacional del Altiplano de Puno, P.O. Box 291, Puno-Peru. Direct inquiries to author Medina (E-mail: wtmedina@ing.puc.cl).
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  • Juan L. Condori,

    1. Authors Medina and Aguilera are with Dept. of Chemical and Bioprocesses Engineering, Pontificia Univ. Católica de Chile, P.O. Box 306, Santiago, Chile. Author de la Llera is with School of Engineering and Applied Sciences, Faculty of Arts and Sciences, Harvard Univ., 29 Oxford St., Cambridge, MA 02138, U.S.A. Author Condori is with El Altiplano SAC Co., Taparachi Industrial Park D-15, Juliaca, San Román, Puno-Peru. Author Medina is also with School of Agroindustries, Faculty of Agrarian Sciences, Univ. Nacional del Altiplano de Puno, P.O. Box 291, Puno-Peru. Direct inquiries to author Medina (E-mail: wtmedina@ing.puc.cl).
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  • José M. Aguilera

    1. Authors Medina and Aguilera are with Dept. of Chemical and Bioprocesses Engineering, Pontificia Univ. Católica de Chile, P.O. Box 306, Santiago, Chile. Author de la Llera is with School of Engineering and Applied Sciences, Faculty of Arts and Sciences, Harvard Univ., 29 Oxford St., Cambridge, MA 02138, U.S.A. Author Condori is with El Altiplano SAC Co., Taparachi Industrial Park D-15, Juliaca, San Román, Puno-Peru. Author Medina is also with School of Agroindustries, Faculty of Agrarian Sciences, Univ. Nacional del Altiplano de Puno, P.O. Box 291, Puno-Peru. Direct inquiries to author Medina (E-mail: wtmedina@ing.puc.cl).
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Abstract

Abstract:  The importance of breakfast cereal flakes (BCF) in Western diets deserves an understanding of changes in their mechanical properties and microstructure that occur during soaking in a liquid (that is, milk or water) prior to consumption. The maximum rupture force (RF) of 2 types of breakfast flaked products (BFP)—corn flakes (CF) and quinoa flakes (QF)—were measured directly while immersed in milk with 2% of fat content (milk 2%) or distilled water for different periods of time between 5 and 300 s. Under similar soaking conditions, QF presented higher RF values than CF. Soaked flakes were freeze-dried and their cross section and surface examined by scanning electron microscopy. Three consecutive periods (fast, gradual, and slow reduction of RF) were associated with changes in the microstructure of flakes. These changes were more pronounced in distilled water than in milk 2%, probably because the fat and other solids in milk become deposited on the flakes’ surface hindering liquid infiltration. Structural and textural modifications were primarily ascribable to the plasticizing effect of water that softened the carbohydrate/protein matrix, inducing partial collapse of the porous structure and eventually disintegration of the whole piece through deep cracks.

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