Supercritical CO 2 -ethanol extraction of oil from green coffee beans: optimization conditions and bioactive compound identification

In this research, a supercritical CO 2 -ethanol extraction was optimized to obtain a green coffee oil rich in bioactive compounds. A face-centered central composite design was used to evaluate the effect of temperature (50–70 °C), extraction pressure (15.0–30.0 MPa), and cosolvent content (5–20%) on the extraction yield and total phenolic compound content of green coffee supercritical extract (GCSE). The experimental data were fitted to a second-order polynomial model. According to the statistical analyses, the lack of fit was not significant for either mathematical model. From the response surface plots, the extraction pressure and cosolvent content significantly impacted the extraction yield, while the total phenolic compound content was impacted by temperature and cosolvent content. The optimal conditions were a 20% cosolvent content, a pressure of 30 MPa, and a temperature of 62 °C, which predicted an extraction yield of 7.7% with a total phenol content of 5.4 mg gallic acid equivalent g GCSE −1 . The bioactive compounds included 5-caffeoylquinic acid (11.53–17.91 mg g GCSE −1 ), caffeine (44.76–79.51 mg g GCSE −1 ), linoleic acid (41.47–41.58%), and palmitic acid (36.07–36.18%). Our results showed that GCSE has the outstanding chemical quality and antioxidant potential, suggesting that GCSE can be used as a functional ingredient.