Perspectives on the use of coffee silverskin in food formulations

In recent years, there has been a growing interest in circular food economy approaches by which wastes from food production processes are reconverted into raw materials for a new cycle. The coffee industry, one of the world's most consumed beverages and the second most traded commodity after petroleum, produces millions of tons of waste each year, including defective beans, husk, pulp, spent coffee grounds, and silverskin. The latter in particular, consists of the skin that coats the coffee bean and is produced during the roasting process. Various studies have highlighted the great potential of silverskin in the formulation of functional foods and prebiotics. In fact, the chemical composition of silverskin turns out to be rich in dietary fibre such as cellulose, hemicellulose and lignin, antioxidants, and phenolic compounds. Among these, chlorogenic acids are of particular importance and make this material interesting from a nutraceutical point of view. Recent studies have shown that the geographical origin has a strong influence on the chemical composition of silverskin, and therefore, the choice of the starting material to be repurposed for food formulations will have, in the future, to take into account its origin. The purpose of this perspective article is to suggest the direction that scientific research should take in order to assess the effective use of coffee silverskin in food formulations, also taking into account safety and traceability aspects.