Evaluation of Colombian Coffee Waste to Produce Antioxidant Extracts

During coffee production, several types of waste such as pulp, mucilage, husk, parchment, coffee silver skin, and spent coffee grounds are generated. The amount of coffee waste and their environmental issues require effective valorization. Those wastes can be used as a source of bioactive compounds. In this work, solid-liquid extraction was used to obtain different solutions, and their phenolic contents, antioxidant capacities, fatty acid profiles, and antimicrobial activities were evaluated. Characterization of the waste materials showed that the highest yield (18.8%) was obtained for spent-coffee grounds. The highest total phenolic contents, caffeine and epicatechin, was observed for coffee pulp extract. Catechin was only observed for parchment. The lipid fraction in the coffee by-products extracts indicated that the spent coffee ground had a higher amount of total lipids, followed by the pulp, and finally the parchment. The most predominant fatty acids in all the extracts were palmitic, stearic, linoleic, oleic, arachidic, and behenic. However, parchment and coffee pulp extracts exhibited an inhibition halo against E. coli bacteria growth.