A Superior All-Natural Antioxidant Biomaterial from Spent Coffee Grounds for Polymer Stabilization, Cell Protection, and Food Lipid Preservation

Treatment with boiling 6 M HCl increases up to 30 times the intrinsic antioxidant potency of spent coffee grounds, leading to a versatile multifunctional material (hydrolyzed spent coffee grounds, HSCG). Spectral and morphological analyses suggest that the remarkable potentiation of the antioxidant activity is due to efficient removal of the hydrolyzable components, mainly carbohydrates, making the polyphenol-rich component available for interaction with free radicals and oxidizing species. HSCG efficiently protects hepatocarcinoma (HepG2) cells from oxidative stress-induced injury and delays lipid peroxidation in fish and soybean oils. Moreover, films made of polyethylene/2% HSCG blends display greater stability to thermal and photo-oxidative degradation. HSCG may thus represent an easily accessible and sustainable alternative to currently available biomaterials with intrinsic antioxidant properties for biomedical, industrial, and technological applications.