SEPARATION PROPERTIES FOR OLIGOSACCHARIDE S OF NANOFILTRATION MEMBRANES AND ITS APPLICATION TO A PURIFICATION PROCESS OF JERUSALEM-ARTICHOKE OLIGOSACCHARIDES

Recently, oligosaccharides have been acknowledged to have physiologica l activity and many of them have been used for food. These oligosaccha rides are generally produced from Various food materials using bioreac tors are separation systems. We studied the separation properties of n anofiltration membranes for model oligosaccharide solutions, and appli ed them to purify oligosaccharides extracted from Jerusalem artichoke (Helianthus tuberosus L.) to develop an oligosaccharide purification s ystem with nanofiltration processes. The observed rejections (Robs) an d the permeate fluxes (J(v)) of four membranes, G 5, G 10, G 20 and G 50, for oligosaccharides having smaller pore sizes in the order in G 5 < G 10 < G 20 < G 50, were evaluated by the batch filtration at vario us pressures. In all of the membranes, J, increased linearly with pres sure. The Robs increased with the molecular weight of oligosaccharide. The Robs for each oligosaccharide became low in sequence from G 5, G 10, G 20 and G 50. It appeared that G 5, G 10 and G 20 had effective p ore sizes to separate the oligosaccharides, and G 50 could remove high molecular weight molecules over 10,000 Daltons. The extract of Jerusa lem artichoke contained fructo-oligosaccharides linking from 2 to 10 s ugar units. In the extract filtrations, membranes rejected oligosaccha rides almost in the same level as the model filtration, however, the f luxes decreased with increase in the concentration of saccharide and/o r high molecules in the extract.