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New research shows how soluble fibres affect dough rheology and gluten structure
Soluble fibres are gaining interest in functional food applications like bread, yet their interactions with gluten and effects on dough rheology are not well understood. Wageningen Food & Biobased Research conducted new research that has shed new light on how soluble fibres interact with gluten, influencing the dough elasticity, and gluten structure.
The study explored protein-fibre interactions by considering the fibres as plasticizers and humectants. Their plasticizing effect depends on the number of available hydrogen bonding sites (NOH,s), while humectant properties relate to the water interaction parameter derived from sorption behavior. By using this physicochemical approach, scientists have uncovered key mechanisms behind phase transitions, thermo-mechanical behavior, and the extensibility of fibre-enriched doughs.
Soluble fibres and gluten interactions in dough
The study explored fibres with different structural characteristics—linear versus branched—both individually and in combination. Results confirmed that these structural properties significantly impact gluten development. A closer look at inulins and polydextrose with comparable molecular weights (Mw), provided new insights into how their molecular structures govern specific interactions with gluten.
High Mw inulins, rich in effective hydrogen bonding sites (NOH,s), were found to enhance gluten network formation by promoting junction zones and branching rate, reducing gaps in the gluten structure. In contrast, the highly branched nature of polydextrose resulted in lower NOH,s availability, leading to reduced branching rate and increased gaps in the protein network. Moreover, polydextrose exhibited greater hygroscopicity than its linear inulin counterparts, affecting dough hydration.
Fibre structure’s impact on dough rheology
These findings emphasized the critical role of fibre structure in gluten interactions, particularly through hydrogen bonding. The study's principles could be instrumental in designing fibre mixtures to optimize dough rheology and gluten structure in fibre-enriched bakery products.
For example, high Mw linear fibres enhance dough elasticity, but their effects can be balanced by combining them with oligosaccharides in specific ratios. This approach could also mitigate the undesirable effects of fibre-rich by-products, such as bran, by precisely modulating gluten hydration and structure with addition of soluble fibers.
Stefano Renzetti, expertise leader Food Formulation at Wageningen Food & Biobased Research says: “Overall, this study provides new mechanistic insights into how soluble fibres interact with gluten, affecting its structure and dough behaviour. These findings could guide the selection and development of functional fibre ingredients from diverse sources, enhancing the nutritional profile of bakery products. Additionally, the study provides insights in protein-fibre interactions, with gluten as example, which could be extended in the future to other plant-protein sources”.