The impact of the oxidants potassium bromate and potassium iodate and the reducing agent dithiothreitol (DTT) on the theological behaviour of 20% (w/v) gluten-in-water suspensions during thermal treatment was monitored with the rapid visco analyser (RVA). The suspensions were subjected to a linear temperature increase from 40 to 95 degrees C in 14 min, a holding step of 40 min at 95 degrees C, a cooling step (7 min) with a linear temperature decrease to 50 degrees C, and a final holding step at 50 degrees C (13 min). Potassium iodate (1.18 and 1.77 mu mol/g protein) and potassium bromate (1.52 and 15.2 mu mol/g protein) decreased RVA viscosities in the holding step and increased sodium dodecyl sulphate (SDS) protein extractabilities suggesting a greater heat resistance and decreased gliadin-glutenin cross-linking. In contrast, in the presence of DTT (1.65 and 3.30 mu mol/g protein) RVA viscosity increased at lower temperatures and lowered SDS extractabilities. It is postulated that low concentrations of reducing agent facilitate gliadin-glutenin cross-linking during heating while oxidants hinder gluten polymerization due to decreased levels of free sulphydryl groups and less flexibility of the glutenin chains. (c) 2006 Elsevier Ltd. All rights reserved.
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