Preparation and properties of wool fabrics dyed with spent coffee ground extract

Spent coffee grounds (SCGs) are solid residues generated from coffee brewing and are mostly discarded as waste. However, SCGs are drawing much attention because they have many health-promoting compounds that exhibit anti-tumor, anti-allergic, antioxidant, and other activities. Therefore, we tried to use SCGs for fabric dyeing to apply functional and coloring effects to the fabrics. SCGs were extracted by a conventional solid-liquid method, and the extract was applied to wool fabrics through a laboratory infrared dyeing machine. It was found that the extract contained a significant number of bioactive components, such as tannins (ca. 0.61 mg/mL); caffeine (ca. 0.38 mg/mL); and phenolic compounds, including chlorogenic acid (ca. 0.21 mg/mL). The wool fabrics dyed with the SCG extract exhibited promising coloring effects, displaying deep-brown hues. In addition, the colorfastness to washing and light were superior to that of fabrics dyed with other natural pigments. In particular, the wool fabrics dyed with the SCG extract showed excellent antioxidant ability (<= 86%) and high levels of ultraviolet blocking (>= 98%).