Dietary fiber-gluten protein interaction in wheat flour dough: analysis, consequences and proposed mechanisms

Apart from starch, non-starch polysaccharides (fibers) play important roles in the functionality of gluten. The effect is more pronounced while preparing fiber-enriched cereal products, where additional fibers add further complexity to the starch-protein network. However, how dietary fibers, even of a small amount, could largely affect the properties of gluten-based doughs or cereal products, is not fully understood and is becoming a topic of recent research. This current review is built on the established conclusions and evidence put forward within the last decade. The importance of fiber-gluten interactions in wheat flour dough is discussed with the focus on the analysis, consequences, and proposed mechanisms. Dietary fiber-gluten interaction is a complex phenomenon and needs an array of techniques not limited to spectroscopy, chromatography, thermo-analysis, and microscopy for proper elucidation. These interactions are related to alterations in the protein secondary and tertiary structures, disulphide bridges, and hydrogen bonding patterns. Current results agree that most of the soluble fibers interact with gluten noncovalently via hydrogen bonding and hydrophobic interactions, whereas whether electrostatic interactions are predominant for anionic soluble fibers is not clear. In the case of the insoluble fibers, the interaction is partly dominated by the degree of swelling and hydration. Moreover, physical mechanisms such as competition for water and steric hindrance play at least equally important roles compared to the chemical aspects such as the molecular weight of soluble fibers and the water binding capacity of insoluble fibers. The understanding of gluten protein interacting with fibers to control structure and related physicochemical properties can help to minimize the variability within the existing system as well as design foods with added functionality.