Molecular Weight Distribution of Polymeric Proteins in Wheat Grains: The Rheologically Active Polymers.

Thierry Aussenac,Larbi Rhazi,Gérard Branlard

doi:10.3390/foods9111675

Abstract

We characterized the molecular weight distribution of polymeric proteins (PP) of bread wheat grains using asymmetric flow field flow fractionation (A4F). The experiment, involving six environmental conditions and 130 cultivars, offered the opportunity to approach the phenotypic values of the polymer characteristics and their contribution of the rheological properties of flours and/or doughs. The contents of high-molecular-weight polymers (MW > 2 × 106 g·mol−1) that can be considered as “rheologically active polymers” (RAPP) for their major contribution to dough baking strength and mixing tolerance were mainly controlled by environmental factors. Under the influence of the growing conditions, at the cellular level, the redox status of non-protein free thiol, such as glutathione, is modified and leads to the formation of polymeric protein-bound glutathione conjugates (PPSSG). The accumulation of these conjugates reduces the formation of the RAPP by limiting the intermolecular interactions between PP in the grain during desiccation. This phenomenon is, therefore, potentially responsible for decreases in the technological properties of the wheat genotypes concerned. These first results invite us to continue our investigations to fully confirm this phenomenon, with emphasis on the behavior of wheat genotypes under various growing conditions.

Highlights

During the last 60 years, in the field of cereal chemistry, the scientific community has been working to determine, in an ever more precise way, the nature of the constituents responsible for the acquisition of technological properties (i.e., breadmaking properties for doughs of bread wheat (Triticum aestivum) and/or pasta properties of durum wheat (Triticum durum))
Based on a large panel of French wheat genotypes grown in contrasting environments, our study aims to (i) better characterize the role of the polymeric protein fraction in the definition of the rheological properties of wheat flours/doughs, (ii) to prioritize the main factors influencing the formation of the polymers of interest as previously defined; and (iii) to highlight the potential effects of some cellular free thiols, in particular glutathione, on the molecular weight distribution of polymeric proteins during grain desiccation
In view of this objective, we implemented the analytical methodology (A4F/MALLS) that, as we have demonstrated in a previous work [25], allows us to go beyond conventional approaches used, such as Size Exclusion high performance liquid chromatography (HPLC) (SE-HPLC) [13,15] or even differential solubility in buffered solutions containing SDS [29,30]

Summary

Introduction

During the last 60 years, in the field of cereal chemistry, the scientific community has been working to determine, in an ever more precise way, the nature of the constituents responsible for the acquisition of technological properties (i.e., breadmaking properties for doughs of bread wheat (Triticum aestivum) and/or pasta properties of durum wheat (Triticum durum)). This practice facilitates the qualification of polymers as “ extractable” and

Methods

Results

Conclusion