Effect of bioprocessing and particle size on the nutritional properties of wheat bran fractions

•Bioprocessing of wheat bran enhanced its nutritional properties.•Antioxidant and phytase activities and nutritional indexes were improved.•Bran of 160 μm showed the best nutritional profile after bioprocessing.

In this work, the influence of bioprocessing on the nutritional quality and health effects of wheat bran of different particle sizes (750, 400, 160, 50 μm) was evaluated. Bioprocessing was carried out by a 24 h-fermentation using Lactobacillus brevis E95612 and Kazachstania exigua C81116 as starters, with or without the addition of an enzyme mixture with specific carbohydrase activities. Bioprocessing clearly affected the microstructure and chemical and nutritional features of wheat bran depending on the particle size. Bioprocessing significantly improved the antioxidant and phytase activities (up to 3.7 fold, respectively), peptides and total free amino acids and content (up to 40%) and the in vitro digestibility of proteins. The antioxidant power and nutritional indexes were higher for the bioprocessed brans compared to the native, mainly in bran having smaller particle size. In every case, the addition of the enzymes further improved the positive effect of the microbial fermentation.Industrial relevanceWheat bran is a source of nutritionally important compounds such as dietary fibers, minerals, vitamins and phenolic acids. Commonly, processing of bran has mostly been performed for technological purposes, to facilitate its use as a DF rich ingredient in foods improving its structural and organoleptic features. The bioprocessing technology here applied offers a tool to enhance also the nutritional value of wheat bran, especially of finer particle size. As a result, bioprocessed wheat bran showed higher potential compared to the native bran, and qualified as a suitable ingredient for food preparations.