|Bekes, Ferenc -|
Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 3, 2011
Publication Date: November 1, 2011
Citation: Anderson, O.D., Bekes, F. 2011. Incorporation of high-molecular-weight glutenin subunits into doughs using 2 gram mixograph and extensigraphs. Journal of Cereal Science. Volume 34, Issue 3. Interpretive Summary: The wheat high-molecular-weight glutenin subunits (HMW-GS) are proteins essential for the formation of dough from wheat flour/water mixtures. The HMW-GS form long polymers that confer the visco-elastic nature to wheat doughs, and are thus important both for wheat utilization and the US farm sector. This report begins a molecular analysis of exactly how the HMW-GS contribute to wheat quality. HMW-GS are used to supplement micro-dough-mixing experiments to observe changes in dough characteristics once the added HMW-GS are incorporated into protein polymers. Results show reproductibility of the assay system, the relative effects of the different types of HMW-GS, and a synergism between subunits.
Technical Abstract: To study the contributions of high-molecular-weight glutenin subunits (HMW-GS) to the gluten macropolymer and dough properties, wheat HMW-GS (x- and y-types) are synthesized in a bacterial expression system. These subunits are then purified and used to supplement dough mixing and extensigraph experiments through dough partial reduction and reoxidation to allow these exogenously added HMW-GS to incorporate into gluten polymers. Detailed results are given for seven mixing and two extension parameters. HMW-GS synthesized in bacteria behaved similarly under these conditions to the same HMW-GS extracted from wheat flour. These experiments initially focused on the HMW-GS of the D-genome of hexaploid wheat encoded at the Glu-D1 locus; e.g., the Dx2, Dx5, Dy10, and Dy12 subunits. Experiments used five different flours and results are shown to be consistent when normalized to results from Dx5 which is included in all experiments. The incorporation of Dx-type subunits into the gluten disulfide bonded network has greater effects on dough parameters than incorporation of Dy-type subunits. When Glu-D1 x- and y-type subunits are incorporated together, there are synergistic effects greater than those with either subunit type alone. This synergistic effect was greatest with approximately equal ratios of Dx- and Dy-type subunits - implying a stoichiometric relationship.