Brewers spent grains are the solid by-products left when the sweet wort is separated from the malt grist after mashing, comprising the insoluble residue of malt and any adjunct grains from which the soluble material has been extracted. Rich in fibre, protein and minerals, they are the largest solid by-product of the brewing process. Their main outlet is animal feed, especially for ruminants, but food scientists are developing uses in human nutrition, including high-fibre bakery and snack products, as well as applications in biofuel, biomaterials and the cultivation of edible fungi.