Cereal Chem 50:553 - 562.  |  VIEW ARTICLE
The Biochemical Basis of Grain Hardness in Wheat.

D. H. Simmmonds, K. K. Barlow, and C. W. Wrigley. Copyright 1973 by the American Association of Cereal Chemists, Inc. 

The possibility was investigated that grain hardness in wheat is associated with differences in the composition of the protein matrix which holds the starch granules together. Such an explanation seems unlikely since hard and soft near-isogenic lines were found to have similar protein composition by protein mapping of gliadin proteins and by gel filtration and dodecyl sulfate electrophoresis of 4M urea extracts of gluten proteins. The degree of adhesion between starch and protein appears to be a more likely explanation of hardness. The amount of soluble material extractable from starch granules prepared from a range of wheats is shown to be a function of hardness. This material contains about 30% protein, and possesses protease, alpha-, and beta-amylase activities. The nonprotein portion is mainly carbohydrate which, on hydrolysis, gives glucose with traces of xylose, arabinose, and mannose.