The physicochemical properties of brewer's spent grain (BSG) and apple pomace (AP), and their effect on dough rheological properties were investigated. BSG had high protein content and both by-products were found to be high in dietary fibre. The rheological and the pasting properties of dough were significantly altered by the addition of by-products, with the main effects being due to the presence of dietary fibre. The biaxial extensional viscosity was significantly higher for the supplemented doughs; the strain hardening index decreased with increasing the levels of flour substitution. The replacement of wheat flour with the by-products significantly reduced the uniaxial extensibility, while the storage modulus, G '', was found to increase, indicating changes in the structural properties of dough. These changes were reflected in the ability of dough to rise during proofing. (C) 2012 Elsevier Ltd. All rights reserved.