Reactivity of sulfhydryls in reduced gluten with lipid hydroperoxides.

Abstract

The reaction of gluten and its components, gliadin and glutenin, with lipid hydroperoxides was studied. The proteins were reduced and incubated with linoleic acid hydroperoxide and monolinolein hydroperoxide at various molar ratios to their sulfhydryl groups under anaerobic conditions. Half of these sulfhydryls were converted to the disulfide form and the other half seemed to be part of higher oxidation products. The formation of interchain disulfide linkages in gluten protein was shown by the increase in the intrinsic viscosity and the production of protein aggregates seen by SDS-polyacrylamide gel electrophoresis. Sulfhydryls in glutenin and gliadin behaved differently toward lipid hydroperoxide. Most of the sulfhydryls in glutenin seemed to be converted to interchain disulfide linkages and those in gliadin to intrachain disulfides at early incubation times and higher oxidation products appeared in both proteins during prolonged incubation. This suggests that the lipid hydroperoxides formed during dough mixing under air lead to the formation of disulfide linkage and build up gluten networks.