Cereal Chem 55:348 - 359. | VIEW
Mixograph Studies. II. Effect of Activated Double-Bond Compounds on Dough-Mixing Properties.
L. F. Schroeder and R. C. Hoseney. Copyright 1978 by the American Association of Cereal Chemists, Inc.
The effects of alpha, beta-unsaturated carbonyl compounds, such as fumaric acid (FA), maleic acid, and ferulic acid (FER), on dough-mixing properties are similar to that of the SH-blocking reagent N- ethylmaleimide (NEMI). NEMI and cysteine, however, interact during dough mixing; cysteine and FA do not. Thiol (-SH) and disulfide determinations showed that mixing in air caused a decrease in -SH groups. KIO3 and NEMI increased the loss of -SH, while FA caused no change in the loss of -SH groups. The disulfide content of dough did not change significantly as a result of addition of FA and NEMI. These results indicate that the effects of FA and related compounds cannot be explained by the thiol-disulfide interchange theory. Fractionation of the flour with water (10:1 water/flour ratio) showed that the mixing properties of the dough were affected by an interaction of the insoluble fraction, gluten plus starch (G+S), and water-soluble (WS) fractions. Further fractionation of the WS fraction indicated that the nondialyzable, heat-stable (WSDB) fraction was most effective in reducing the mixing time of G+S; that fraction has been reported to contain FER. The dialyzable fraction of water solubles (WSDZ) did not affect dough stability, but did reduce mixing time. An interaction of the WSDB and WSDZ fractions apparently caused dough breakdown. Fast-acting oxidants increased the rate of dough breakdown of G+S only when the WS fraction was present or when compounds containing activated double bonds were added. The effects of alpha, beta- unsaturated compounds were reversed by lipoxidase present in enzyme-active soybean flour and antioxidants, which inhibit free radicals reactions. Thus, the alpha, beta-unsaturated compounds appear to have their effect by their reaction with free radicals created in the gluten proteins during dough mixing.