Spent coffee grounds vary in particle size and moisture content depending on the brewing process and grind size. Typically dark brown to black with a granular texture, these grounds retain a high concentration of organic compounds and nutrients. Chemically, they are composed of 45-55% carbon and 2-2.5% nitrogen, making them a valuable source of organic matter. They also contain around 40% total fiber, including cellulose (8%) and hemicellulose (36%). While most caffeine is extracted during brewing, residual amounts (<0.5%) remain, along with proteins (10%), lipids (up to 16%), and bioactive compounds such as chlorogenic acids (2.3%), which offer antioxidant benefits (Mendes dos Santos et al., 2021).

Given their rich composition, spent coffee grounds have found a promising role in the cosmetic industry. Their high concentration of antioxidants and anti-inflammatory compounds makes them particularly effective in skincare, especially in facial masks that help protect the skin from oxidative stress and promote a healthy complexion. Furthermore, the residual caffeine content enhances circulation, making coffee grounds useful in reducing dark circles, evening out skin tone, and addressing cellulite.

To unlock these benefits, the spent coffee grounds must first be dried and ground into a fine powder. This powder is then subjected to an extraction process using a suitable solvent—such as water, ethanol, or oil—to isolate the desired bioactive compounds. After the extraction is complete, the liquid extract is separated from the solid grounds through filtration to remove impurities. The resulting concentrated extract can then be incorporated into various cosmetic formulations, including lotions, creams, and masks. By repurposing coffee waste in this way, the cosmetic industry can create natural and sustainable skincare solutions that align with growing consumer demand for eco-friendly products.

Sources:

• ICO 2024, Beyond Coffee: Towards a Circular Coffee Economy coffee-development-report-2022-23.pdf
• Mendes dos Santos, É., Malvezzi de Macedo, L., Lacalendola Tundisi, L., Ataide, J. A., Camargo, G. A., Alves, R. C., Oliveira, M. B. P. P. (2021). Coffee by-products in topical formulations: A review. Trends in Food Science & Technology, 111, 280-291. https://doi.org/10.1016/j. tifs.2021.02.064