Aggregation of gluten proteins in model dough after fibre polysaccharide addition

•Dietary fibre polysaccharides addition induced aggregation of gluten proteins.•Competitive water binding of polysaccharides caused dehydration of gluten network.•Gluten aggregation and dehydration are confirmed by structural and thermal analyses.

FT-Raman spectroscopy, thermogravimetry and differential scanning calorimetry were used to study changes in structure of gluten proteins and their thermal properties influenced by four dietary fibre polysaccharides (microcrystalline cellulose, inulin, apple pectin and citrus pectin) during development of a model dough. The flour reconstituted from wheat starch and wheat gluten was mixed with the polysaccharides in five concentrations: 3%, 6%, 9%, 12% and 18%. The obtained results showed that all polysaccharides induced similar changes in secondary structure of gluten proteins concerning formation of aggregates (1604 cm−1), H-bonded parallel- and antiparallel-β-sheets (1690 cm−1) and H-bonded β-turns (1664 cm−1). These changes concerned mainly glutenins since β-structures are characteristic for them. The observed structural changes confirmed hypothesis about partial dehydration of gluten network after polysaccharides addition. The gluten aggregation and dehydration processes were also reflected in the DSC results, while the TGA ones showed that gluten network remained thermally stable after polysaccharides addition.