Arabinoxylan (AX) is an abundant hemicellulose in wheat bran and an important functional component in bakery products. This review compares preprocessing and extraction methods, and evaluates their effect on AX properties and functionality as a bread ingredient. The extraction process results in AX isolates or concentrates with varying molecular characteristics, indicating that the process can be adjusted to produce AX with targeted functionality. AX functionality in bread seems to depend on AX properties but also on AX addition level and interactions with other components. This review suggests that the use of AX with tailored properties together with properly optimized baking process could help increasing the amount of added fiber in bread while maintaining or even improving bread quality.

Feruloylated arabinoxylan (AX) is a potential health-promoting fiber ingredient that can enhance nutritional properties of bread but is also known to affect dough rheology. To determine the role of feruloylation and hydrolysis of wheat bran AX on dough quality and microstructure, hydrolyzed and unhydrolyzed AX fractions with low and high ferulic acid content were produced, and their chemical composition and properties were evaluated. These fractions were then incorporated into wheat dough, and farinograph measurements, large and small deformation measurements and dough microstructure were assessed. AX was found to greatly affect both fraction properties and dough quality, and this effect was modulated by hydrolysis of AX. These results demonstrated how especially unhydrolyzed fiber fractions produced stiff doughs with poor extensibility due to weak gluten network, while hydrolyzed fractions maintained a dough quality closer to control. This suggests that hydrolysis can further improve the baking properties of feruloylated wheat bran AX. However, no clear effects from AX feruloylation on dough properties or microstructure could be detected. Based on this study, feruloylation does not appear to affect dough rheology or microstructure, and feruloylated wheat bran arabinoxylan can be used as a bakery ingredient to potentially enhance the nutritional quality of bread.

Wheat bran is a milling side stream rich in dietary fiber and bioactive compounds that is predominantly used for animal feed. Increasing the food use of wheat bran as a fiber ingredient could improve the nutritional quality of baked products and sustainability of cereal processing. In this thesis, the potential of modified wheat bran arabinoxylan extracts as fiber ingredients was explored by investigating the relationship between extract properties and functionality in breadmaking. Ferulic acid content and molar mass of extracts were reduced, and the effect of these modified extracts on dough and bread quality was analyzed. An extraction process combining extreme temperatures with a decolorization process was tested to increase extraction yield while improving extract properties. Reduction of arabinoxylan molar mass improved both dough and bread quality in terms of dough extensibility and specific volume of bread. This effect was connected to viscosity and water-holding capacity of the extracts. Hydrolyzed and feruloylated extracts produced bread and dough quality closest to control, supporting the potential for feruloylation and molar mass reduction to be used in combination to enhance bread quality and shelf life. Yields from subcritical water extraction comparable to alkali extraction were achieved through increased treatment temperature while improving the color of the extracts through ultrafiltration and active charcoal treatment. The findings of this thesis demonstrate the potential of modified wheat bran arabinoxylan extracts as functional fiber ingredients, and therefore help to facilitate the use of wheat bran in production of health-promoting ingredients for bread.