Changes in SDS Solubility of Glutenin Polymers During Dough Mixing and Resting
Résumé
An on-line coupling of HPSEC-MALLS and a RP-HPLC procedure were used to characterize and to reveal the polydispersity of the glutenin polymers of doughs during mixing and resting. Experiments involved doughs prepared from several samples of a common French wheat cultivar (Soissons) differing in total amount of SDS-unextractable glutenin polymers. During dough mixing the amounts, the size distribution of protein and the glutenin subunit composition within the SDS-unextractable polymers changed. However, the major changes in SDS-unextractable glutenin content and size distribution occurred before the peak MT was reached, while detectable changes in subunit composition occurred also after the peak MT. Even if sonication, which was used to solubilize the total wheat glutenin, can narrow down the glutenin size distribution, HPSEC-MALLS revealed a close relationship between the SDS solubility of the glutenin polymers and their size distribution confirming a depolymerization and repolymerization hypothesis. During the depolymerization of the SDSunextractable polymers, glutenin subunits were released in nonrandom order, which was indicative of the polymers' having a hierarchical structure. Some HMW-GS (specially HMW-GS 1Dx5) were particularly resistant to the depolymerization mechanism. This suggested that the subunit plays a major role in forming the backbone of the SDS-unextractable polymers consistent with its potential to form branched structure. These studies suggest that the SDSunextractable polymers in flours have a well-ordered structure that can be modified by dough mixing and resting.
Domaines
Sciences du Vivant [q-bio]
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