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Effect of incorporated high and low molecular glutenin subunits on dough extensibility. I. M.
VERBRUGGEN (1), W. S. VERAVERBEKE (2), and J. A. DELCOUR (1). Laboratory for Food
Chemistry, Katholieke Universiteit Leuven, Kardinaal Mercierlaan 92, B-3001 Heverlee, Belgium.
Wheat glutenin, a polymer of high and low molecular weight glutenin
subunits (HMW-GS and LMW-GS) linked together through disulfide bonds, is important for the
bread-making properties of wheat flour. The contribution of these subunits can be investigated by increasing their
concentration in the flour. However, because GS form a part of the glutenin network, they must be
incorporated into this network. Total HMW-GS and LMW-GS were simply 'added' to or 'incorporated'
into the glutenin network of a base flour. Dough extensibility was measured with the TA-XT2 Texture
Analyser. HMW-GS and LMW-GS had totally different effects on dough extensibility parameters. Because
'addition' and 'incorporation' of GS had similar effects on MR and EX, it seems probable that even without
reduction/reoxidation GS were partially incorporated in the presence of oxygen. Blocking the free
sulphydryl groups in glutenin subunits by alkylation changed the effects of these subunits on MR and EX.
To exclude the possibility that incorporation of glutenin subunits may require additional oxidant and thus
may lower the concentration of available oxidant for restoration of partially reduced doughs, an
'incorporation with excess KIO3' was also performed. However, the use of high concentrations of oxidant
seems to overrule the effects of added GS or may force GS to incorporate differently from what can be
observed under gentle oxidation conditions.
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