Extracting and purifying polyphenols from coffee pulp (Coffee arabica L.) using aqueous two-phase systems

Abstract

Coffee pulp, the major by-product of the beverage industry, is considered as an environmental threat, but also possesses high amounts of bioactive compounds. The extraction of these compounds by using conventional methods and solvents usually accompanies impurities. Here, an aqueous two-phase system (ATPS) was optimized to extract and purify polyphenols from coffee pulp. Key affecting factors include phase system composition (ethanol and ammonium sulfate), extraction time and temperature while the quality of product was evaluated based on total phenolic content (TPC) and antioxidant activity (AA). The final optimized conditions were at 50 °C for 60 min using the ATPS of ethanol 37.7% (w/w) and ammonium sulfate 25% (w/w). TPC and AA at the optimal conditions were 434.63 ± 25.40 mg GAE/g dw and 622.71 ± 9.65 mg TE/g dw, respectively, which were higher than the results of the extract only used ethanol as the extraction solvent. The results showed that ATPS was a valuable method to extract and purify coffee bioactive compounds.