H. Matsumoto, I. Oshima, and I. Hlynka. Copyright 1960 by the American Association of Cereal Chemists, Inc.
Wheat proteins extracted from flour with N/100 acetic acid following a preliminary extraction with water were treated with bisulfite. The increase in sulfhydryl content was followed titrimetrically, using the mercury pool electrode. Only a small increase in -SH was found after 3-minute reaction time. A rapid increase in -SH followed in the next 2 or 3 hours. Urea increased the rate at which equilibrium was attained. With the addition of acetaldehyde a rapid decrease in -SH content was observed at pH 6 and 7 and a slower decrease at pH 4 and 5. N-ethylmaleimide and bromate decreased the titration value prominently. The equilibrium constant for the reaction of bisulfite with wheat proteins was obtained. The above chemical effects are supported by the physical effects of bisulfite and acetaldehyde on the mixing characteristics of dough in the farinograph.