Modification of wheat bran arabinoxylan extracts for functional properties in breadmaking

Abstract

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.