Extraction of green coffee oil using supercritical carbon dioxide

Abstract

Supercritical CO2 extraction was used to refine coffee oil obtained by mechanical pressing. Extractions were carried out using 50–70 ◦C and pressures ranging from 15.2 to 35.2MPa, with a CO2 flow rate of 1 standard L/min using a semi-continuous high-pressure extraction apparatus. Green coffee oil fractions were collected at fixed time intervals and the composition of each fraction was determined by HPLC analyses. Caffeine and traces of chlorogenic acid were detected in the first fractions while waxes remained in the extraction vessel. Compared with the original oil the triglyceride composition remained almost unchanged in the fractions. The results also indicate an increase of triglyceride and caffeine extraction with pressure. An increase in extraction temperature results in a retrograde behavior over the pressure range of 15.2–28.3MPa. At pressures higher than 30MPa the solubility behavior of coffee oil was apparently independent of the temperature. A good correlation of the solubility data of green coffee oil was obtained using the Chrastil equation.