Implementation of integrated membrane processes for pilot scale development of fractionated milk components

Numerous opportunities For the separation and Fractionation of milk and whe y components are presented as a result of continuing developments in filtra tion membranes modules and processes. The preparation of sufficient quantit ies of selected protein groups for functionality studies and food applicati on tests requires considerable amounts of starting material, particularly i n the case of whey-based constituents. Adequate amounts of membrane filtrat ion surface area are, therefore, needed in order to expedite processing tim e, limit conditions for microbial growth and increase productivity from a p roduct development point of view. With this objective in mind, a series of large pilot plant membrane separation systems based on microfiltration, ult rafiltration and electrodialysis were recently installed and commissioned. Rapid ultrafiltration of whey for the generation of high protein concentrat es under a wide variety of conditions, including 'cold' filtration, is faci litated by a Memtech(TM) spiral wound membrane plant with a maximum surface area of 144 m(2) that is accommodated within 3 modules mounted in parallel . Designed to operate on a continuous feed-and-bleed principle, product is heated while pumping via a plate-heater to the plant's balance tank in orde r to raise temperature to the desired operating condition. Magnetic now met ers mounted on the feed, permeate and diafiltration water lines enable the volume concentration ratio to be controlled throughout a run. Defatting of rennet whey by microfiltration using a Tetra Pak Alcross(TM) M, Type 2 x 19 Special, crossflow microfiltration (MF) plant fitted with a 0.1 mu m pore size ceramic membrane with a filtration area of 13.3 m(2) trebled flux rate during ultrafiltration at 12 degrees C under steady state conditions. High protein whey protein concentrates (ca. 80% total protein) were processed i n the defatted and nondefatted state at either 50 degrees C or 12 degrees C for functional characterisation, Preliminary analyses indicate that all 4 WPC's produced weak gels. Native phosphocasein was prepared from skim milk using the above MF plant. Partial demineralisation of skim milk prior to MF was facilitated using an Ionics (Ionics Inc.) Electromat(TM) ED, featuring a 100-cell pair Mark III electrodialysis membrane stack. Electrodialysis r esulted in improvements in the heat stability profile of phosphocasein, at the expense of rennet coagulation properties which were totally eliminated even in the presence of added calcium.