Brewer's spent grain: its value as renewable biomass and its possible applications

Climate change, depletion of fossil resources, constant population growth and increasing energy demand are issues of great concern. The idea of valorising tonnes of industrial waste produced on the planet every year appears as a possible pathway for a sustainable growth. Among different alternatives, lignocellulosic biomasses (LCBs) are the most important, abundant and cheap resource available. They are obtained from crops and organic agricultural or industrial waste as bio-degradable by-products. Therefore, LCBs represent a versatile, renewable, widely available and low-cost raw material that can be potentially used to produce biofuels, new materials and chemical compounds, satisfying the industry's desire to move towards a green transition. The brewery's spent grain (BSG) is the main by-product of the brewing industry (about 85% of total by-products), generated in massive amounts throughout the year. It represents a raw material with an interesting chemical composition that has shown to have the potential to be used in different industrial exploitations. This study summarises some of the relevant research on BSG valorisation starting from the simplest case of its use as an ingredient for animal feed up to the production of biofuels and the recovery of value-added compounds.