ON THE CONVENTIONAL CROSS-FLOW MICROFILTRATION OF SKIM MILK FOR THE PRODUCTION OF NATIVE PHOSPHOCASEINATE

The use of conventional microfiltration for the production of native p hosphocaseinate was studied at 50 degrees C using a microporous cerami c membrane of 0.22 mu m pore diameter at a flow velocity of 6.9 m s(-1 ) and a transmembrane pressure of 190 kPa. Flux declined by approximat ely 50% from an initial value of 180 L h(-1) m(-2) over the course of 3 x concentration. Batch diafiltrations after dilution of the retentat e with distilled water or 0.08 M NaCl at pH 7.0 raised the flux for bo th media to the initial value or higher, followed by a similar pattern of flux decline during the concentration step. The procedure allowed the preparation of native phosphocaseinate containing 79% protein with a casein to total protein nitrogen ratio over 0.91.