Dry-fractionation of wheat bran increases the bioaccessibility of phenolic acids in breads made from processed bran fractions

This study evaluated the potential of using ultra-fine grinding and electrostatic separation of wheat bran as methods to improve the bioaccessibility of para-coumaric acid (pCA), sinapic acid (SA) and ferulic acid (FA) from bran-rich breads. Bran fractions were produced and used to bake white bread, whole-grain bread, and seven different bran-rich breads. The influence of bran particle size and bread composition on the bioaccessibility of pCA, SA and FA was studied using a dynamic computer-controlled in vitro gastro-intestinal model. The amount of bioaccessible phenolic acids was higher in whole-grain bread and bran-rich breads than in white bread, and the finer the bran particles in bran-rich breads, the more bioaccessible the phenolic acids. The highest amounts of bioaccessible phenolic acids were observed for two of the fractions obtained by electrostatic separation of ground bran. Only the free and conjugated phenolic acids forms were found to be bioaccessible, and the bioaccessibility of SA was much higher than that of FA, due to the higher solubility of SA. This study demonstrated that the use of bran fractionation to reduce the particle size, or to include only some parts of the bran in foods, can help developing grain-based products with increased nutritional potential.