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Cereal Chem 69:401-404   |  VIEW ARTICLE

Effect of Starch Gelatinization on Physical Properties of Extruded Wheat- and Corn-Based Products.

S. E. Case, D. D. Hamann, and S. J. Schwartz. Copyright 1992 by the American Association of Cereal Chemists, Inc. 

Wheat flour, wheat starch, corn meal, and corn starch were extruded in the form of a half-product using a pilot-plant model twin-screw extruder. Starch was gelatinized from 20 to 100%. The final cooked product (vegetable oil, 196 C) was tested for texture using the Kramer shear press on an Instron universal testing machine. As gelatinization increased, volume of the puffed product increased and bulk density decreased. A minimum bulk density was achieved at approximately 75% gelatinization for all products except corn meal, which had a minimum density at approximately 55% gelatinization. Peak force at failure had a parabolic response to gelatinization. The same force is required for failure at high and low extents of gelatinization, although textural and physical attributes differed substantially. Gelatinization was modeled by the ratio of total energy to peak force at failure (Et/PkF) from the Instron data, which was influenced by the combination of bulk density and deformability.

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