Experiments
2.1. Plant material preparation
Leaves of cultivars (Chemlali) and bark of tree were collected
in October 2011 from the region of Sfax (Central Tunisia).
These materials have been dried in the shadow at room temperature
(25 C), for 8 days, (see Issaoui et al., 2012). Samples
were taken into the laboratory and dusted carefully the same
day, and then ground into small pieces (1–3 mm). Approximately
30 g from each sample was prepared to be loaded into
the supercritical reactor. The obtained powder was vacuum
packed until its use. Before utilization, the material was comminuted.
CO2 (purity 99%) was supplied by SIO (Societa` Italiana
Ossigeno, Cagliari, Italy).