Effects of Bran Treatment on Rheology and Sensory Quality of Whole Wheat Flat Bread
This entry is also available in the Theses and Dissertations section of Open Prairie.
The purpose of this research was to study the differences in the quality of 100% whole wheat flour (WWF) when the bran fraction was subjected to mild solvent treatment before reconstitution with the endosperm. The bran treatments included water washing and washing with ethanol solutions (50% and 100%). WWF prepared with untreated bran served as the control. Effects of these treatments on particle size, chemical composition, color, dough rheology, product formulation, and sensory characteristics of 100% whole wheat flour were studied. Grains of five HRSW cultivars (Advance, Prevail, Select, Brick and Forefront) were milled using a Quadrumat Senior mill. Gluten analysis of patent white flour obtained from five HRSW showed Brick and Advance to have superior gluten quality for bread baking. Washing the bran with 50% ethanol significantly lowered redness (a*) while washing the bran with 100% ethanol significantly lowered yellowness (b*). Brick cultivar was found to be superior in Farinograph data in relation to dough development time (DDT), dough stability (DS), breakdown time (BT), and mixing tolerance index (MTI). Of the four bran treatments used, washing with 50% resulted in significantly higher DDT, BT and lower MTI, in contrast to the control. Washing with 100% ethanol resulted in significantly higher DS and lower MTI compared to the control. Cultivars Brick and Prevail had significantly high Rmax/Ei and cultivars Advance and Forefront had the lowest Rmax/Ei. Flour with 50% ethanol-treated bran had the highest Rmax/ERmax and control (WWF) had the lowest. Control (WWF) had significantly high Emax while flour with ethanol treated bran (both at 50% and 100% strength) had significantly low Emax. Brick and Prevail were superior varieties in terms of dough extensibility. Results from the one dimensional extensibility test indicated that tortillas made from the flour incorporated with 50% and 100% ethanol-treated bran were good in relation to stretchability, while the control (WWF) was found to be desirable in relation to elasticity. Treatments of bran were not discerned in tortilla colors and sensory attributes.