Novel Dry Fractionation Technologies Applied to Wheat Bran

摘要

Wheat bran,obtained after conventional milling of wheat grains for the production of white flour,is a fibre rich undervalued by-product used for animal feeding.Bran represents about 15％ of the wheat grain after milling and is a composite multi-layered material made up of several adhesive tissues:outer pericarp,inner pericarp,testa,hyaline layer,and aleurone layer,plus some attached starchy endosperm residues.These layers are characterized by different structures and compositions:the outer pericarp and inner pericarp are rich in branched heteroxylans and cellulose (insoluble dietary fibres),the testa is a hydrophobic layer containing a cuticle rich in lipidic compounds,and the aleurone layer is made of cells enclosing bioactive compounds (B vitamins,minerals,antioxidants),surrounded by thick cell walls composed of relatively linear arabinoxylans and b-glucans (dietary fibres),and of few proteins.These bioactive compounds are poorly bio-accessible as they are trapped in resistant aleurone cell-walls.