Green coffee extracts rich in diterpenes – Process optimization of pressurized liquid extraction using ethanol as solvent

In this study, a pressurized liquid extraction (PLE) was optimized to obtain green coffee extract rich in cafestol and kahweol diterpenes. The effects of temperature (T) and static time (St) (time of contact between the solvent and the matrix during each cycle or batch) on global yield, cafestol and kahweol concentrations and antioxidant activity were studied. The greatest green coffee extract global yield (9.78%) was obtained at 70 °C and 8 min St. PLE at 74 °C and 6 min St presented the highest concentration of cafestol (20.08 g/kg extract) in the green coffee extract, whereas, the highest kahweol concentration (25.16 g/kg extract) was obtained at 60 °C and 6 min St. The extracts showed high DPPH• antioxidant activity, particularly after PLE at 50 °C and 8 min St (EC50 1.56 μg/mL of extract). This extract also presented a high total phenolic content (35.99 mg GAE/g of extract).