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Controlled Stepwise Reduction of Disulfide Bonds and Heat-Induced Modification of Wheat Dough Proteins

¹Novo Nordisk Biotech, 1445 Drew Avenue, Davis, CA 95616. ²Corresponding author. Phone: 530-757-8100. Fax: 530-758-0317. E-mail: fengxu@nnbt.com ³Novo Nordisk A/S, Novo Allé, Bagsværd, DK-2880, Denmark. ⁴Novo Nordisk BioChem North America, State Road 1003, Franklinton, NC 27525.

A reducing solution of 2-mercaptoethanol and its oxidized form 2-hydroxyethyl disulfide, whose variable concentrations set variable disulfide reduction potentials, was applied to progressively reduce the disulfide bonds of proteins extracted from doughs made from Meneba and Robin Hood flour. Several dough proteins had disulfide bonds stronger than those of other dough proteins. A SDS-sedimentation method was applied to monitor the baking of dough into bread. Dough proteins susceptible to heat (baking) were studied by SDS-fractionation, extraction with reducing alcoholic solution, SDS-PAGE, and N-terminal protein sequencing. High or low molecular weight glutenins, α, β, and γ-gliadins, α-amylase inhibitor, and α-amylase trypsin inhibitor were identified among the dough proteins modified by heat (as shown by reduced solubility in aqueous-SDS solution). The heat-induced modification of the gliadins and glutenins might contribute to the coagulation of dough proteins, while the heat-induced modification of the amylase or trypsin inhibitors might contribute to the regulation of endogenous or exogenous amylolytic or proteolytic activities in dough or bread.