The extractable caffeine (Xp) was considered an adjustable parameter, but the 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.