Reactivity of wheat gluten protein during mechanical mixing: radical and nucleophilic reactions for the addition of molecules on sulfur.

Mechanical properties of gluten-based biomaterials, such as break stress, were known to be influenced by temperature and shear stresses applied during processing. It is well documented in literature that these processing parameters promoted wheat gluten protein aggregation. Exchange between disulfide bonds and thiol groups oxidation are the postulated mechanisms that lead to gluten protein solubility loss in sodium dodecyl sulfate buffers. Both nucleophilic and radical reactions were postulated to act during gluten aggregation. To graft molecules on gluten, a study was carried out to explore the reactivity of its thiol and disulfide groups during thermomechanical mixing. A range of reactants able to react via radical or nucleophilic pathways with thiol groups were synthesized. Reactivity between gluten and functions was quantified by gluten solubility measurements. This investigation and literature observations allowed proposal of a general gluten aggregation mechanism during mixing.