Cereal Chem 64:3-8   |  VIEW ARTICLE

Studies on Heavily Ground Flour Using Roller Mills. II. Chemical Alteration of Proteins, Particularly Globulin, During Dough Mixing.

K. Okada, Y. Negishi, and S. Nagao. Copyright 1987 by the American Association of Cereal Chemists, Inc. 

The chemical changes in proteins of flour during heavy grinding and dough mixing were studied by gel filtration on Sephacryl S-300, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and by determining the rate of aggregation of proteins, stored at -20 C in 0.5% sodium dodecyl sulfate solution containing 1.6 x 10(-3)M N-ethylmaleimide. Overgrinding of flours caused little change in the elution profiles of extracts of flour or dough according to gel filtration. On the other hand, the rate of aggregation of proteins, stored at -20 C in 0.5% sodium dodecyl sulfate solution containing 1.6 x 10(-3)M N- ethylmaleimide, increased with more passes through the rolls and with dough mixing. The results suggested that the conformation of flour protein is changed by overgrinding and mixing, so that denaturation of flour protein is more easily caused by frozen storage. Wheat flour globulin was fractionated into three fractions, namely, a high-molecular-weight fraction (HMW-globulin), a medium-molecular-weight fraction (MMW- globulin), and a low-molecular-weight fraction (LMW-globulin) by gel filtration on Sephacryl S-300. MMW-globulin was especially reactive and polymerized into HMW-globulin by forming S-S bonds during mixing; that of overground stream X (a late-break flour) was more reactive than others. Globulins in wheat flour may play an important role as binders between proteins during dough mixing, thus affecting the rheological properties of dough.