A change of anthocyanins under different conditions of enzymatic treatments, clarification and concentration was determined. A pectin preparation Klerzyme^®120, manufactured by DSM, France, specific for "sour fruits" with pH below 3.2, was used for maceration and depectinization. Experiments were carried out by a laboratory hydraulic press. Raw raspberry juice was clarified either by membranes separation processes or by traditional treatments using gelatin and bentonite.

Raw depectinized apple juice was clarified in a laboratory scale ultrafiltration (UF) system using ceramic tubular membranes (Tech-Sep Carbosep) with a molecular weight cut-off of 300,000, 50,000, and 30,000 daltons. The experiments have been carried out over a wide range of transmembrane pressures (100-400 kPa), temperatures (293-328 K), and feed flow rates (100-900 mL/min). Permeate flux significantly decreased with time until a steady state was established.