Fig. 1 shows the overall extraction curve (OEC) obtained using
pure CO2 and the three cosolvents in the static-SFE. The highest
extraction rates of caffeine at the early extraction stages were
obtained with CO2 + EL, while the lower extraction rates resulted
with pure CO2. The early extraction rate of caffeine were calculated
on the basis of the first kinetic data collected (after 14 min
of CO2 flow) and were 0.063 mg/min in the case of pure CO2
and 0.098 mg/min, 0.289 mg/min and 0.486 mg/min, respectively,
for CO2 + EAC, CO2 + ETOH and CO2 + EL. Then, ethyl lactate was
the most efficient cosolvent and can produce a caffeine recovery
enhancement close to 7 in comparison with pure CO2.