Pressurized-fluid extraction of cafestol and kahweol diterpenes from green coffee

• Coffee diterpene extraction was evaluated through pressurized-fluid extraction.
• Temperature and flow rate effects are correlated with diterpenes recovery.
• Extraction time has a crucial role in the improvement of the extraction process.
• Kinetic thermal degradation of diterpenes is assessed.

Cafestol and kahweol were extracted from green coffee beans (C. arabica) using a pressurized-fluid extraction (PFE) system. The effects of extracting solvent (i.e. water, ethanol and methanol), flow rate (0.5, 1.0, 2.0 and 3.0 mL · min− 1), extraction temperature (60, 80 and 100 °C) and time on extraction efficiency of coffee diterpenes were investigated. Quantification of diterpenes extracts was achieved by HPLC-UV method. The solvent flow rate was clearly the most significant process parameter. Diterpenes recovery resulted also influenced by temperature, except for the lowest flow rate, indicating solubility and mass transfer constraints. Kinetic degradation was also examined suggesting a thermolability of the diterpenes at 100 °C. The optimum extraction conditions were 100 °C and 3.0 mL · min− 1 using methanol. Under these conditions, PFE showed a remarkably higher efficiency compared with conventional extraction techniques.Industrial relevanceCoffee is the world's most traded food commodity. Coffee-specific diterpenes (i.e. cafestol and kahweol) are high-value bioactive compounds, naturally occurring in the coffee lipid fraction. However, they are not easy to separate and likely to be unstable when isolated. High-pressure extraction, namely pressurized fluid extraction (PFE), appears as an attractive option as it reduces extraction time, thus avoiding degradation of thermolabile compounds, while requiring smaller quantities of solvent than traditional extraction methods (e.g. Soxhlet). PFE offers the possibility to operate with a wide range of liquid solvents well above their boiling point, but very little information can be found on the effect of operational conditions to efficiently recover coffee diterpenes. Such knowledge provides a basis for the rational design of PFE processes and, may be useful to allow industrial scale-up interpretation for coffee diterpenes extraction.