Global caffeine yield (Xo) was assessed on the basis of the maximum
yield attained in each OEC; 1% above the total amount of
extract for each experiment as reported in Table 4. The extractable caffeine (Xp) was considered an adjustable parameter, butthe same
Xp/Xo ratio was considered for all OECs, since the same vegetal
material (crushing and cell disruption) was employed and thus, it
is presumed that the same percentage of caffeine is easy accessible
in the constant rate period. Then, the Xp/Xo ratio and the mass
transfer coefficients in the fluid and solid phase (kYA and kXA) were
adjusted to reproduce the experimental OECs.