Microfiltration performance has been analysed by evaluating the influence of three macro-compounds as a function of the cross-flow velocity (CFV), transmembrane pressure (TMP) and pore size of the membranes. Four mathematical models were evaluated to relate the permeate flow rate (J p) to the concentration of the macrocompounds in the retentate (C b) during filtration in concentration mode. Pectin has a greater impact than cellulose and lignin on the permeate flux (J p). The largest value of K 2 was found for pectin in the model 1 1 2 − = + ⋅ p b J K K C. The optimum operating conditions and pore size to reduce fouling of the membranes depend on the pore size to particle size ratio and the physicochemical interactions between the solute and membrane. The mathematical model is useful in the region where the permeate flow is nearly independent of pressure, the pore size and cross-flow velocity but is dependent on the diffusional phenomenon of mass transfer.

The cross-flow microfiltration (CFM) of fruit juices allows obtaining products of high quality by conserving their organoleptic characteristics and microbiological stability during storage. The effect of the main macro-compounds and the transmembrane pressure (TMP) on the process performance with model fluids was evaluated. The model fluids concentration varied between 0.25 and 0.75% for pectin and 0.04 and 0.08% for cellulose. To study the influence of transmembrane pressure (TMP) and concentration on the hydrodynamic properties of the fouling layer ( , diffusivity (D) and the boundary layer thickness ) the Box-Behnken design with three replicas in the center was used. It was found that the CFM process is efficient and commercially feasible when working at a constant TMP of 1.93 bar and at concentrations of pectin and cellulose of 0.25% and 0.0513%, respectively.