EFFECT OF WHEAT BRAN PARTICLE-SIZE ON DOUGH RHEOLOGICAL PROPERTIES

Commercial hard red spring, hard red winter, soft white and durum whea t brans were used to investigate the effect of wheat bran particle siz e on the rheological properties of doughs. Wheat brans were first coar sely ground and passed through a bran finisher to remove additional en dosperm and aleurone layers. These processes increased total dietary f ibre content and decreased starch content of the wheat bran samples. T hree particle size distributions, for each wheat bran class, were obta ined by further grinding (not by sifting) of the bran samples by diffe rent experimental mills. Coarse bran can retain significantly more wat er than medium or fine bran as measured by a centrifuge method, but br an particle size had no significant effect on dough water absorption. Addition of wheat bran into bread dough systems increased dough water absorption rate, reduced mixing time and decreased dough mixing tolera nce as measured by farinograph. Fine particle size wheat bran decrease d dough mixing tolerance and reduced mixing time compared to coarse br an. Dough containing fine particle size bran exhibited more strength t han dough containing coarse bran after a 180-min rest period as measur ed by the extensigraph.