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Effect of redox reactions in vitro on gluten polymer moleculer weight as measured by flow field-flow
fractionation and multi angle laser light scattering. A. A. TSIAMI, L. E. Thomas, and J. D. Schofield.
The University of Reading, Department of Food Science and Technology, Reading RG6 6AP, UK.
Well-characterised gluten fractions were prepared to study the effect of
dehydroascorbic acid (DHAA) and glutathione (GSH) on gluten protein in vitro. Salt precipitation
from acetic acid dispersions of gluten proteins was the procedure used to prepare the gluten fractions from
cv. Hereward (medium strong flour). The fractions were characterized by Flow FFF and MALLS in
terms of their MW distributions and by SDS-PAGE in terms of their subunit compositions. The fractions
ranged from high molecular weight (HMW) (R2-R4) to low molecular weight (LMW) (R5-R6) gluten
polymers. The HMW fractions were rich in glutenin polymers enriched in HMW-subunits, whereas the
LMW fractions comprised small glutenin polymers enriched in low MW subunits of glutenin plus gliadins.
Addition of DHAA to solutions of the protein fractions in 0.05-M acetic acid and 0.002% (w/v) of the
detergent FL-70 increased the MW distribution of all fractions except for the HMW fraction R2. There was
no effect of GSH on fraction R2, but there were decreases in the MW distributions of the rest of the glutenin
polymer fractions (R3, R4 and R5). There was no effect on the LMW fractions (R6, R7). Similar behaviour
was observed when the redox treatments were applied to complex dough systems.
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