Crossflow microfiltration of passion fruit juice after partial enzymatic liquefaction

To obtain clarified passion fruit juice, crossflow microfiltration after en zymatic liquefaction was studied using ceramic membranes with 0.2 mu m pore size. The effect of a high-rate enzymatic treatment for the degradation of suspended solids was assessed, resulting in the selection of a commercial enzymatic preparation. Partial enzymatic liquefaction of cell-wall polysacc harides prior to microfiltration provided an unusual pattern of flux increa se after a short decline when crossflow velocity was high (7 m s(-1)). It w as found that a synergistic effect between pectinase and cellulase activiti es enhanced permeate flux increase. With total recycling at 36 degrees C, t he combination of low transmembrane pressure (150 kPa) and high enzyme conc entration (1 ml l(-1)) provided the highest flux (113 1 h(-1) m(-2)). These conditions were then assessed with concentration in order to verify indust rial feasibility and evaluate physicochemical characteristics of final prod ucts. A volumetric reduction ratio of 3 was maintained during 18 h without any decrease in permeate flux, which fluctuated around 40 1 h(-1) m(-2). Th e quality of permeate was satisfying even its aromatic strength was weakene d. Retentate had similar characteristics of raw juice and could be recycled in order to use its residual enzyme activity. (C) 2000 Elsevier Science Lt d. All rights reserved.