This is similar to the current finding that
the oil extracted by SFE contented less 1,8-cineole compared to
that extracted by hydro-distillation, and that supercritical CO2
extracted high molecular weight compounds as well. It was
explained [7] that high-molecular weight compounds including
esters, fatty acids, and waxy-like compounds are more likely to
be extracted by CO2 rather than by hydro-distillation which more
easily extract the volatile compounds [7]. However, the opposite
observations were reported in Della Porta et al. [8] who found that
the 1,8-cineole content was higher in supercritical carbon dioxide
extraction (62.6%) than in hydro-distillation(48.2%). This was
because they performed two fractions during the extraction
process. The volatile oil was recovered in the second separator
and therefore had higher cineole content, whereas waxes was
recovered in the first separator. They suggested that the optimum
fraction would be achieved by operating at 90 bar and 10 C in
the first separator and 15 bar and 15 C in the second.