clean technologies Article Study of Influential Parameters of the Caffeine Extraction from Spent Coffee Grounds: From Brewing Coffee Method to the Waste Treatment Conditions Alexandre Vandeponseele, Micheline Draye , Christine Piot and Gregory Chatel * EDYTEM, University Savoie Mont Blanc, CNRS, F-73000 Chambéry, France;
[email protected] (A.V.);
[email protected] (M.D.);
[email protected] (C.P.) * Correspondence:
[email protected] Abstract: This article aims to study the interest of spent coffee grounds (SCG) valorization through caffeine recovery. In an original way, this study takes into account all the parameters such as (i) the brewing coffee methods (household, coffee shops, etc.); (ii) the storage conditions, in particular the drying step; (iii) the solid/liquid extraction parameters such as the nature of solvent, the temperature, the extraction time and the solid/liquid ratio; and (iv) the liquid/liquid purification parameters such as the nature, the volume and the pH of extraction medium. Results have shown that spent coffee grounds from coffee-shops obtained by percolation contain a higher amount of caffeine than spent coffee grounds from households obtained from spent pods or filters. A drying treatment is not required when extraction is performed under one week after the spent coffee grounds collection −1 with 96.4% of not degraded caffeine. Solid/liquid extraction performed with 25 mL.g SCG of Citation: Vandeponseele, A.; Draye, hydroalcoholic solvent (water/EtOH, v/v 60/40) at 60 ◦C during 15 min have given a caffeine yield M.; Piot, C.; Chatel, G. Study of −1 up to 4.67 mg.g SCG.