Cereal Chem. 71:195-199   |  VIEW ARTICLE


The Effects of Bromate (0-30 ppm) on the Proteins and Lipids of Dough.

J. F. Panozzo, F. Bekes, C. W. Wrigley, and R. B. Gupta. Copyright 1994 by the American Association of Cereal Chemists, Inc. 

The bromate response in dough, as measured by an improvement in loaf volume, has been shown to be largely variety dependent, with some environmental effect too. For the samples and baking procedure used in this study, potassium bromate (5-10 ppm) was required to achieve the optimum loaf volume (at 2.5 min of constant mixing time). Subsequent additions of potassium bromate (up to 30 ppm) resulted in a toughening of the dough and a decline in loaf volume. Bromate changed the apparent molecular weight distribution of proteins and lipid extractability. Fractionation of glutenin proteins by size- exclusion, high- performance liquid chromatography identified an extra large glutenin aggregate, PI, associated with bromate addition. However the proportion of this aggregate continued to increase with bromate levels, beyond those required for maximum loaf volume. Thus, we concluded that this aggregate is not a major contributor to the loaf-volume effect. The composition of the protein extractable with 70% aqueous ethanol was also examined by size-exclusion, high- performance liquid chromatography. The high molecular weight fraction from this material (a lipid-mediated aggregate) followed a trend similar to that of the loaf-volume response to bromate. Lipid extractability changed with bromate addition, although lipid composition was unaltered. The bromate-response factor appears to be the result of noncovalent aggregation of low molecular weight proteins together with a decrease in lipid extractability due to lipid binding.