Microwave-assisted extraction of green coffee oil and quantification of diterpenes by HPLC

The microwave-assisted extraction (MAE) of 13 different green coffee beans (Coffea arabica L.) was compared to Soxhlet extraction for oil obtention. The full factorial design applied to the microwave-assisted extraction (MAE), related to time and temperature parameters, allowed to develop a powerful fast and smooth methodology (10 min at 45 °C) compared to a 4 h Soxhlet extraction. The quantification of cafestol and kahweol diterpenes present in the coffee oil was monitored by HPLC/UV and showed satisfactory linearity (R2 = 0.9979), precision (CV 3.7%), recovery (<93%), limit of detection (0.0130 mg/mL), and limit of quantification (0.0406 mg/mL). The space–time yield calculated on the diterpenes content for sample AT1 (Arabica green coffee) showed a six times higher value compared to the traditional Soxhlet method.