Concentration of blackcurrant juice by reverse osmosis

The aim of this study was to examine the applicability of reverse osmosis (RO) for the concentration of blackcurrant juice by AFC-80 polyamide tubular membrane that has a salt rejection greater than 80%. The fresh juice had a total soluble solids content of about 16.58Brix. The effect of centrifugation followed by depectinization with two commercially available pectinase enzyme preparations (Panzym Super E and Trenolin Rot DF) on the permeate flux has been evaluated. For the description of the concentration process, the resistance-in-series model has been used. It was concluded that the applied RO membrane is suitable for concentration of blackcurrant juice up to 28.68Brix, which was achieved with the juice that had been treated with Panzym Super E. The total resistances were calculated and compared, taking into account membrane fouling and polarization layer resistance.

The scope of this study was to examine the applicability of a RO process for the concentration of blackcurrant juice by AFC-80 polyamide tubular membrane. Blackcurrant juice is very popular among consumers due to its high content of mineral salts, C-vitamin, P-, B1- and B2vitamins and also provitamin A. The different enzyme pretreatment, with two commercially available pectinase enzyme preparation (Panzym Super E and Trenolin Rot DF) of the fresh juice for enzymatic depectinization was investigated. The highest concentration ratio was observed in case of PSE pretreatment. The TSS content of the concentration rose to 28.2 for Panzym Super E., 25.7 for Trenolin Rot at 68C, 25.4 for Trenolin Rot at 258C and 22.4 for Control frozen juice. The highest permeate flux of 20 L m(2 h(1 and TSS of 28.28Brix was achieved in the concentration of juice that has been previously depectinized by Panzym Super E. There were no significant differences between the two Trenolin treatments in the terms of permeate flux; therefore, it is advisable that the depectinization process is carried out at room temperature as it does not require the extra energy needed for refrigeration. The greatest permeate flux was achieved in the concentration of juice that has been previously depectinized by PSE enzyme. The highest drop of flux was observed in case of PSE as a result of the highest concentration and viscosity growth. During the concentration of blackcurrant juices by RO, the dominant resistances were the membrane resistance and the polarization layer resistance. The depectinization effects of PSE and Trenolin enzymes were obvious, which decreased the different resistances and increased the flux. PSE strongly decreased fouling, while the effect of Trenolins was lower. The highest concentration polarization effect was observed in the Control and the lowest in the juice treated with PSE enzyme. Finally, it can be concluded that RO is a viable method for concentration of blackcurrant juice with the applied membrane at 60 bar transmembrane pressure and 258C operating temperature. To improve the filterability of blackcurrant juice and to reach high end concentration of the retentate, application of the PSE enzyme is recommended in industrial size application.