Physicochemical characterization and microbiota modulatory potential of brewer’s spent grain and arabinoxylan-derived fractions: A valorization study

Brewer’s spent grain (BSG), one of the largest by-products generated by brewing industries, holds a wealthy nutritional value due to its content in proteins and fibres. Although some initiatives have explored alternatives for leveraging the nutritional value of BSG, it mostly remains an underexploited source of valuable ingredients for human nutrition, being mainly dedicated to animal feed and landfilling. BSG is rich in hemicellulosic material, composed of arabinoxylans (AX), which have been postulated as emergent prebiotics, capable to confer health benefits through modulating the gut microbiome. In this work we comprehensively investigated in vitro the composition and gut microbiome modulatory potential of BSG and AX fractions on human microbiota of two population groups by means of fecal batch fermentations and 16S rRNA gene sequencing. The gut microbiome modulatory effects was influenced by the specific BSG/AX fraction; the population group (healthy or Crohn’s disease (CD) patients) and by interindividual variation. For instance, Dorea and Eubacterium halli which include well-known fibre degrading, and health promoting bacteria, were only stimulated in fermentations of fractions with high arabinose and xylose contents. This work demonstrates diverse modulatory capacity of distinct AX fractions, diversifying alternative BSG valorization strategies through exploitation of novel prebiotics tailored to specific groups.