Effect of solvent, method, time and temperature of extraction on the recovery of phenolic compounds and antioxidants from spent coffee grounds

Abstract

Abstract The spent coffee grounds (SCG) are one of the byproducts generated in large volume by the coffee industry. Thus, this study aimed to evaluate solvents and methods of extraction of bioactive compounds from SCG and optimize the process. The solvent and the extraction method had a significant effect on the extraction yield of the bioactive compounds. Through the extraction kinetics, it was verified that 90 min was a sufficient time for the recovery of phenolic compounds. In general, the pure solvents had a lower extraction yield than the ethanol/water mixture and the rise in temperature, along with an ethanol/water mixture, proved to be favorable to the extraction process. Under optimized conditions it was possible to obtain 9.15 (mg GAE/g SCGd.b), 0.58 (mg QE/g SCGd.b), 255.55 (g SCGd.b/g DPPH) and 0.042 (mM Fe(II)/g SCGd.b) for TPC, flavonoids, antioxidant capacity (DPPH) and antioxidant capacity (FRAP), respectively.