Advances in the valorization of brewing by-products

Beer is the most consumed alcoholic beverage worldwide, and its production involves the generation of a huge volume of by-products (i.e., spent grain, spent hop, and spent yeast). This review aims to highlight the main properties of these by-products as a valuable source of biomolecules (i.e., proteins, cellulose, hemicellulose, lignin, phenolic compounds, and lipids) and the biorefining methods used in the last decade for their valorization. The pros and cons of the technologies employed will be shown, highlighting which of them could be more ready for the transition to an industrial scale, and which applications (e.g., food and feed, bioenergy, biochemicals, and biomaterials) are the most feasible.