Upcycling Coffee Waste: Key Industrial Activities for Advancing Circular Economy and Overcoming Commercialization Challenges

The valorization of coffee waste has gained traction due to its potential to generate valuable products, lessen its impact on the environment, and promote sustainability. This review examines the diverse range of coffee waste, including pulp, husk, mucilage, and parchment from the upstream processing of green beans, as well as silverskin (coffee chaff) and spent coffee grounds (SCGs) generated during roasting and brewing. These materials are identified as valuable raw inputs for biorefineries pursuing a bio-circular economy. Recent research has yielded several viable applications for these by-products, categorized into four main areas: (1) agriculture, (2) biofuels and bioenergy, (3) biochemicals and biomaterials, and (4) food ingredients and nutraceuticals. Despite significant advancements in research, the industrial application of coffee waste remains limited. This review summarizes the global commercialization landscape, highlighting that SCGs are particularly advantageous for large-scale upcycling, with applications spanning agriculture, biofuels, and biochemicals. In contrast, coffee husk is primarily utilized in food ingredients and nutraceuticals. The review also addresses the challenges and constraints that must be overcome to facilitate successful commercialization.