A superior antioxidant biomaterial from spent coffee grounds: cell protection, food lipid preservation and in vitro digestion

We report herein a novel antioxidant biomaterial, named hydrolyzed spent coffee grounds (HSCG), from overnight treatment of spent coffee grounds (SCG) with 6 M HCl, at 100 °C.1 The biocompatibility and cytoprotection properties of HSCG were investigated in comparison with SCG on hepatocarcinoma (HepG2) cells. HSCG proved to be non-toxic at doses as high as 500 microg/mL and efficiently protected cells from oxidative stress-induced injury at 1-10 microg/mL. HSCG efficiently delayed thermal and iron-induced lipid peroxidation in fish and soybean oils. The modifications induced by in vitro gastrointestinal digestion followed by a fermentation step on the antioxidant activity of HSCG as measured by several chemical assays were also investigated. A significant antioxidant capacity was observed for both the bioaccesible (soluble) and particularly the indigestible fraction. HSCG may thus represent an easily accessible and sustainable alternative to currently available biomaterials with intrinsic antioxidant properties for biomedical applications, food preservation and food supplements.