Bioactives extraction from spent coffee grounds and liposome encapsulation by a combination of green technologies

Valorization of agro-industrial waste by the extraction of bioactive molecules and their activity preservation by encapsulation is an open topic in process engineering. In this work, a combined approach for the recovery of antioxidants from spent coffee grounds by High Pressure and Temperature Extraction and the entrapment of extract into liposomes using the Supercritical assisted Liposome formation process was proposed. High Pressure and Temperature Extraction showed that high extraction performances (43 ± 2.3 mg Caffeic Acid Equivalents /gDried Spent Coffee Grounds, 59 ± 3 μg Trolox Equivalents/L extract) can be obtained working under inert atmosphere at 150 °C, 60 min using ethanol 54 % (v/v) as solvent. For extract preservation, liposomes were produced by Supercritical assisted liposome formation, investigating different operating pressures and varying the extract cargo into liposomes. Results indicated that 100 bar as operative pressure and 18 mg Caffeic Acid Equivalents /g liposomes as total polyphenol loading allowed to obtain high encapsulation efficiency (89 %), small liposome size (about 200 nm) and without significant reduction of loading antioxidant activity (7%).