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R. J. Stenberg and W. F. Geddes. Copyright 1960 by the American Association of Cereal Chemists, Inc. Wheat starch pastes (10%) with and without single and multiple additions of wheat gluten, glucose, lactose, shortening, and nonfat dry milk, prepared at pH values of 4.4, 5.4, and 6.4, were stored at 75 C. for 25 days. The sugars were the principal ingredients which caused browning, as measured by reflectance of the dried pastes at 600 millimicrons. Browning was accompanied by increases in reducing substances, even in pastes made without sugars. Aqueous ethanol extracts of the stored pastes exhibited absorption maxima at approximately 275 millimicrons, a region where carbonyl compounds show strong absorption. Chromatographic separation on magnesium sulfate of the 2,4-dinitrophenylhydrazones prepared from ethanol extracts of a browned paste made with wheat starch, gluten, and sucrose at pH 6.4 yielded 13 "nonacid" and 17 "acid" carbonyl derivatives. The absorbance of these derivatives did not correspond to that of the corresponding hydrazones of 5-hydroxymethylfurfural or levulinic acid. |
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