Depolymerization of the Glutenin Macropolymer During Dough Mixing: I. Changes in Levels, Molecular Weight Distribution, and Overall Composition

Abstract

Cereal Chem. 76(3):395-401Changes in the amounts, molecular weight distributions, and levels of major groups of subunits in the glutenin macropolymer (GMP) of doughs during mixing were investigated. The GMP (gel protein) is the unreduced fraction of gluten protein that remains as a layer on top of the starch after extraction of SDS-soluble proteins and centrifugation. Experiments involved doughs prepared from flours derived from one weak and one strong cultivar and lines derived from cv. Olympic that were null for specific high molecular weight glutenin subunits (HMW-GS). During mixing, the amount of GMP decreased; the major changes occurred before peak mixing time (MT, achievement of peak resistance). In addition, the average apparent molecular weight of GMP (determined by both size-exclusion HPLC and multilayer gel electrophoresis) decreased during mixing, but in this case, the major changes were seen later in the mixing process, during dough breakdown. Even after extensive mixing, polymers and oligomers were released, not free glutenin subunits. During dough breakdown, the composition of GMP also changed, such that the proportion of HMW-GS decreased but β-amylases/D low molecular weight glutenin subunits (LMW-GS) increased. Changes in the total amounts of other LMW-GS typically were smaller with a decrease in the proportion of B subunits and an increase in the proportion of C subunits. The major changes in GMP composition were observed after peak MT (peak resistance) occurring earlier and to a greater extent in the weaker dough. Our results suggest that dough breakdown during mixing may be triggered by loss of HMW-GS, leading to changes in the molecular weight distribution and composition of the disulfide-bonded GMP.Covalent and noncovalent interactions between the major polypeptide constituents in dough underly the unique ability of wheat flours to form elastic, extensible dough. After initial hydration of flour through mixing with water and other components, the next step in dough development is formation of a gluten network. Glutenforming proteins deposited in protein bodies in the endosperm disrupt and become fully hydrated, forming a continuous gluten network in which starch granules are embedded. At optimal development, aggregates unfold, and a physical network of gluten polypeptides bound by both disulfide and noncovalent bonds forms (Kasarda 1989, Weegels et al 1996a. Any attempt to understand the biochemical basis for genetic and environmental differences in dough rheological behavior requires an understanding of the composition of subunit polypeptides and how they interact. Both covalent bonds (intermolecular disulfides) and noncovalent interactions are important in the formation and behavior of doughs (Ewart 1977, Ng et al 1991. However, although knowledge of the effects of variation in the allelic composition of some individual gluten polypeptides on dough quality recently has improved (reviewed by Skerritt 1998), our understanding of how polypeptides specifically interact to determine dough proper...

The impact of redox agents on further dough development, relaxation and elastic recoil during lamination and fermentation of multi-layered pastry dough

“…These results are in agreement with those of earlier research for bread dough (Weegels et al, 1997a,b;Lagrain et al, 2007) where an increase in SDS-EP content upon bread dough mixing was also reported. In this context, it is relevant to mention that Weegels et al (1997a,b) have suggested that partial depolymerisation of glutenin during dough mixing occurs, that Skerritt et al (1999) suggested breaking of disulphide bonds of the GMP during mixing and a subsequent formation of new SS-bonds with 'chain-terminating' polypeptides, that Don et al (2005) reported a transition of spherical glutenin particles in flour to disrupted, non-spherical glutenin particles in mixed dough, and that Lagrain et al (2007) ascribed the increase in SDS-EGLU contents upon mixing to mechanical disruption of glutenin and formation of protein aggregates from this partially disrupted glutenin through hydrogen bonds and hydrophobic interactions.…”

Effect of Structural and Physicochemical Characteristics of the Protein Matrix in Pasta on In Vitro Starch Digestibility

“…During mixing or sheeting, the dough became more elastic, 9 and the solubility of glutenin proteins (the elastic protein component in gluten) increased due to protein disaggregation and depolymerization of the glutenin polymer. 10,14,15 Figure 3 shows changes in the distribution of glutenin proteins in the pasta during sheeting from 3 passes and 45 passes. We observed that with increasing sheeting passes the quantity of the SDS-soluble polymeric glutenin increased, with a concurrent decrease in the SDS-insoluble polymeric glutenin.…”

Microstructure, mechanical properties, and starch digestibility of a cooked dough made with potato starch and wheat gluten

“…Depending of the mechanism (type of movement) and extension of the kneading process, the dough can become more or less elastic as a result of the conformation and integrity of the gluten matrix obtained (Hayta & Alpaslan, 2001;Morgenstern, Zheng, Ross, & Campanella, 1999;Skerritt, Hac, & Bekes, 1999;Sutton et al, 2003). The rupture stress and rupture strain of cooked samples are shown in Fig.…”