Changes in Sulfhydryl Groups and Hydrodynamic Behavior of Thiolated Polyvinyl Alcohol Reacted with Oxidized Lipid

A synthetic polymer, thiolated polyvinyl alcohol (SH-PVA), was used for examining the reaction between sulfhydryls and lipids during dough mixing. When SH-PVA was incubated with linoleic acid hydroperoxide at a concentration of 1/12 to 1/4 mole to a mole of SH group, progressive oxidation of sulfhydryl was observed and a part of disulfides seemed to be further oxidized in some cases. The hydrodynamic behavior of SH-PVA treated with oxidized linoleic acid was similar to that of SH-PVA treated with an oxidizing agent, potassium bromate; non-Newtonian flow and increase in viscosity were observed. The peak of the gel filtration pattern of SH-PVA shifted to a faster elution position upon treatment with oxidized linoleic acid. These results probably indicate the formation of an interchain disulfide linkage. In view of these results, we discussed the role of lipids involved in oxidation of free SH groups in the rheological properties of gluten and dough.