Bio-recycling of spent coffee grounds: Recent advances and potential applications

Coffee (Coffea) is one of the largest-selling beverages in the world, creating a large amount of waste. The spent coffee grounds (SCG) contain numerous organic compounds (fatty acids, amino acids, polysaccharides and polyphenols) and minerals with extremely high economic value for recycling and thus have the potential to be used in the pharmaceutical and cosmetic industries. Several studies have indicated various products that can be valorised from SCG, including biofuel, biopolymers, food components (such as bioactives, i.e. antioxidants), food additives, animal feed and construction materials. This review briefly summarises the composition of SCG, mainly focusing on bio-reusing products and standard recycling methods available today, with trends for future applications and potential directions.