Enrichment of diterpenes in green coffee oil using supercritical fluid extraction – Characterization and comparison with green coffee oil from pressing

Abstract

Supercritical fluid extraction (SFE) was used to obtain green coffee oil (Coffea arabica, cv. Yellow Catuaí) enriched in the diterpenes, cafestol and kahweol. To obtain diterpenes-enriched green coffee oil relevant for pharmaceuticals, a central composite rotational design (CCRD) was used to optimize the extraction process. In this study, pressure and temperature did not have influences on cafestol and kahweol concentrations, but did affect the total phenolic content (TPC), which ranged from 0.62 to 2.62mg GAE/g of the oil. The analysis and quantification of diterpenes according to gas chromatography indicated that green coffee oil from SFE presented a cafestol content of 50.2 and a kahweol content of 63.8g/kg green coffee oil under optimal conditions. The green coffee oil produced from conventional pressing methods presented lower diterpenes content of 7.5 and 12.8g/kg green coffee oil for cafestol and kahweol, respectively. When SFE was used, the content of the diterpenes in the same green coffee beans was relatively higher, approximately 85% for cafestol and 80% for kahweol. Green coffee oil from SFE also presented fatty acids, such as palmitic acid (9.3mg MAE/g green coffee oil), the polyunsaturated linoleic acid (ω-6; 11mg MAE/g green coffee oil) and oleic acid (ω-9; 3.8mg MAE/g green coffee oil). The physical properties for green coffee oil produced from SFE and conventional pressings showed that densities and viscosities decreased with temperature. For oils produced from both extractions, the density behaviors were similar with values ranging from 0.9419g/cm3 (25°C) to 0.9214g/cm3 (55°C) from pressings and 0.9365g/cm3 (25°C) to 0.9157g/cm3 (55°C) for the oil obtained by the SFE. The dynamic viscosity for the pressed oil ranged from 127.8798mPa×s (25°C) to 35.0510mPa×s (55°C); for the oil from SFE, these lower values ranged from 84.0411mPa×s (25°C) and 24.2555mPa×s (55°C).