Temperature‐Induced Changes in the Dynamic Rheological Behavior and Size Distribution of Polymeric Proteins for Glutens from Wheat Near‐Isogenic Lines Differing in HMW Glutenin Subunit Composition

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Abstract
Viscoelasticity of hydrated gluten depends on composition of HMW gluten subunits (GS), size distribution of glutenin polymers, and proteinprotein interactions. Glutens extracted from four near‐isogenic lines with differing HMW‐GS were analyzed. Rheological properties were studied by dynamic assay in shear. Size distribution of prolamins was determined by sequential extraction and size‐exclusion HPLC. Assays performed at 20°C confirmed that viscoelasticity was determined by large glutenin polymers. The abundance of large glutenin polymers depended on the HMW‐GS composition of the lines. Difference of functionality linked to subunit structure was highlighted by comparing the behaviors of the 1A/1B null and 1A/1D null lines. Glutens were submitted to heating and cooling cycles, with or without an SH‐blocking agent (N‐ethylmaleimide [NEMI]). At 20–40°C, no irreversible changes of the mechanical properties occurred. Thermal treatment affected chain mobility, and possibly H bonds, but not the chemical structure of the network. At >40°C, irreversible rheological changes were observed without NEMI. Irreversibility was mainly due to chemical modifications affecting the polymer size distribution through SH‐SS exchange reactions. The sensitivity of gluten to temperature depended on subunit composition.

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