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

Abstract

Cereal Chem. 76(6):931-937A 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.

Effects of added fruit polyphenols and pectin on the properties of finished breads revealed by HPLC/LC-MS and Size-Exclusion HPLC

“…5) are within the range of published data (Lagrain et al, 2005;Manu & Prasada Rao, 2008;Singh & MacRitchie, 2004). The assembling of gluten proteins into large polymeric molecular structures in the gluten network is closely associated with the disulphide bond formation (Schofield, Bottomley, Timms, & Booth, 1983;Xu et al, 1999). A decrease in S-H groups in a bread may be associated with the conversion of S-H groups into S-S bonds during the breadmaking, leading to a reduced extractability of gluten proteins and an elevated %UHMW (Koh & Ng, 2009), due to the disulphide-sulphydryl bond formation (Weegels, Verhoek, de Groot, & Hamer, 1994) and the formation aggregates via protein cross-linking (Maforimbo, Skurray, Uthayakumaran, & Wrigley, 2006;Schofield et al, 1983;Wrigley & Bekes, 1999).…”

“…Introducing an antioxidant like PPs into the bread system would have complicated the processes further, as the addition of PPs may affect the redox status of the S-H groups, and the added PPs may lead to the oxidation of the free S-H group depending on their relative reduction potentials (Frei, 1994;Rao, 1971;Wolin & Mohazzab-H, 1997;Xu et al, 1999). The presence of added PPs may cause direct oxidation of an S-H group in a glutenin molecule to a stable form that won't take part in further disulphide-sulphydryl interchange reactions, or cause an -S-S-bond to be formed between a water-soluble protein -S-H group and a glutenin -S-H group and/or between two glutenin -S-H groups during bread dough development.…”

Modifications of Wheat Flour Proteins during in Vitro Digestion of Bread Dough, Crumb, and Crust: An Electrophoretic and Immunological Study

“…The T−SDS-PAGE pattern of the undigested crumb (Figure ) was rather similar to that of the undigested dough but with a lower band definition, which was particularly evident for the digested samples. This had to be related to the effect of baking on the crumb proteins, which resulted in heat-induced protein modification and breakdown ( , ). However, as observed with the dough samples, the storage proteins rapidly disappeared during digestion.…”

Proteinaceous inhibitors of carbohydrate‐active enzymes in cereals: implication in agriculture, cereal processing and nutrition

“…In baking, α‐amylase inhibitors and α‐amylase/trypsin inhibitors were identified among the dough proteins modified by heat (as shown by reduced solubility in aqueous SDS solution). 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 92, 93. It has, moreover, been demonstrated using a proteomics approach that some of these inhibitory CM proteins and ASIs are targets of cereal thioredoxin h,94–97 although it still remains to be investigated to what extent these reactions have technological importance.…”