Physicochemical, techno-functional and antioxidant characterization of coffee silverskin

Coffee residues have been considered a valuable source of nutritional and functional components, thus are considered as a potential ingredient for foods. The aim of this study was to evaluate the physicochemical, techno-functional, and antioxidant properties of coffee silverskin flakes and powder. The results indicated that coffee silverskin flakes and powder showed pH near to neutrality, and the color was Roman coffee and Deep coffee, respectively, which show that milling process change this parameter. Coffee silverskin flakes showed the highest water and oil-holding capacity, while both coffee residues exert slight swelling and foam capacity, and foam stability, without effect of milling process. However, both residues do not exert emulsion and gelling capacity, as well as emulsion stability. The presence of phenols, flavonoids, caffeoylquinic acid and alkaloids (powder > flakes) were detected in both residues, which exert free-and radical-cation scavenging activity (powder = flakes), reducing power properties, and lipid oxidation inhibition (powder > flakes). In conclusion, coffee silverskin can be proposed as a functional ingredient for food industry.