Figure 4 shows the physical appearances of the oil extracts.
The extracted oils were yellow in color at lower
pressure of 10 MPa, then gradually changed to green
with increasing pressure at all extraction temperatures.
In other words, the amount of extracted non-volatile
compound such as pigment increases with increasing
SC-CO2 pressure due to increasing SC-CO2 density.
Therefore, it is expected that essential oils with different
quality can be recovered by changing operating conditions
especially that of pressure.