Raman studies of gluten proteins aggregation induced by dietary fibres

Interactions between gluten proteins and dietary fibre preparations are crucial in the baking industry. The addition of dietary fibre to bread causes significant reduction in its quality which is influenced by changes in the structure of gluten proteins. Fourier transform Raman spectroscopy was applied to determine changes in the structure of gluten proteins modified by seven dietary fibres. The commercially available gluten proteins without starch were mixed with the fibres in three concentrations: 3%, 6% and 9%. The obtained results showed that all fibres, regardless of their origin, caused the same kind of changes i.e. decrease in the alpha-helix content with a simultaneous increase in the content of antiparallel-beta-sheet. The results indicated that presence of cellulose was the probable cause of these changes, and lead to aggregation or abnormal folding of the gluten proteins. Other changes observed in the gluten structure concerning beta-structures, conformation of disulphide bridges, and aromatic amino acid environment, depended on the fibres chemical composition. (C) 2015 Elsevier Ltd. All rights reserved.