Extraction of antioxidant phenolic compounds from spent coffee grounds

► Antioxidant phenolic compounds were extracted from spent coffee grounds (SCG). ► The used methanol concentration and solvent/solid ratio affected the extraction. ► Use of 60% methanol at 40 ml/g SCG was established as the best extraction condition. ► A phenolic-rich extract (16 mg GAE/g SCG) with FRAP of 0.10 mM Fe(II)/g was produced. ► Flavonoids, chlorogenic acid, and protocatechuic acid were present in SCG extracts.