Influence of wheat bran on wheat dough rheology and subsequent texture of bread

摘要

One of the most efficient ways to increase the fibre content of bakery products is to supplement part of the flour with cereal bran. However, addition of high amount of bran is a technological challenge, both in terms of flavour and texture of the final product. One of the main phenomena influencing on the structure of the yeast fermented matrix is the formation and stability of cellular structure in the dough. The aim of this work was to assess the changes due to bran addition (level and type) along bread-making chain by measuring the dough rheological properties. Native bran and two types of bioprocessed bran (fermented with and without enzymes) were studied at the addition level of 10, 15 and 20 %. Inulin was also used to test the effects of a soluble fibre.. Rheological properties of bran were assessed with lubricated squeezing flow (LSF) for large strains and with Kieffer dough and gluten extensibility rig for uniaxial extension. Bread texture was analysed by measuring specific volume, density, instrumental texture by Instron compression test and bread structure by assessing crumb granulometry with 2D image analysis. Both free standing and panned bread types were used to evaluate impact of bran on the bread quality. Addition of wheat bran had significant impact on dough and bread properties in a dosedependent manner. The higher the amount of added bran, the more the dough and bread characteristics were altered; but in a non linear manner. Specific volume of bread decreased and density increased 0-40 % depending on the addition level and type of bran and bread type. Bread crumb evenness and fineness were altered accordingly depending on the addition level of bran. Addition of bran modified the rheological properties of dough, which may partly be explained by the observed differences in bread texture.