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

Abstract

Numerous opportunities for the separation and fractionation of milk and whey compo- nents are presented as a result of continuing developments in filtration membranes modules and processes. The preparation of sufficient quantities of selected protein groups for functionality stud- ies and food application tests requires considerable amounts of starting material, particularly in the case of whey-based constituents. Adequate amounts of membrane filtration surface area are, there- fore, needed in order to expedite processing time, limit conditions for microbial growth and increase productivity from a product development point of view. With this objective in mind, a series of large pilot plant membrane separation systems based on microfiltration, ultrafiltration and electrodialysis were recently installed and commissioned. Rapid ultrafiltration of whey for the generation of high pro- tein concentrates under a wide variety of conditions, including 'cold' filtration, is facilitated by a Memtech™ spiral wound membrane plant with a maximum surface area of 144 m 2 that is accom- modated 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 order to raise temperature to the desired operating condition. Magnetic flow meters mounted on the feed, permeate and diafiltration water lines enable the volume concentration ratio to be controlled through- out a run. Defatting of rennet whey by microfiltration using a Tetra Pak Alcross ™ M, Type 2 〈 19 Spe- cial, crossflow microfiltration (MF) plant fitted with a 0.1 μm pore size ceramic membrane with a fil- tration area of 13.3 m 2 trebled flux rate during ultrafiltration at 12 °C under steady state conditions. High protein whey protein concentrates (ca. 80% total protein) were processed in the defatted and non- defatted state at either 50 °C or 12°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 (Ion- ics Inc.) Electromat™ ED, featuring a 100-cell pair Mark III electrodialysis membrane stack. Elec- trodialysis resulted 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.