Whey protein fractionation using membranes.

Two processes for the fractionation of whey proteins have been developed by researchers in Europe and tested at laboratory and pilot-plant scales. In the first process, the proteins are in a soluble form during membrane separation. In the second process, some of the proteins are selectively precipitated before membrane separation.

The aim of both processes is to obtain purified a-lactalbumin (a-lactalb) and b-lactoglobulin (b-lactoglob) from bovine serum albumin (BSA) and immunoglobulin (immglob). Investigators found that an open ultrafiltration membrane gave a selective separation of a-lactalb and b-lactoglob from BSA and immglob in reconstituted whey protein concentrate (the first process). When scientists optimized feed composition and process conditions, they obtained a permeate with more than 99.9% of a-lactalb and b-lactoglob.

This permeate can be further treated to obtain a higher level of purity for the two proteins. An 80% pure a-lactalb and a more than 95% pure b-lactoglob were obtained after further processing. A whey protein concentrate with similar amounts of b-lactoglob and a-lactalb was obtained as a byproduct.

In the second process, researchers precipitated a-lactalb, BSA, immglob and a permeate highly enriched in b-lactoglob. They obtained a product that was 90% pure after membrane processing. Further treatment of the precipitate by redissolving and ultrafiltering it resulted in a 76% pure a-lactalb. Engineering tools were developed and used for the design, optimization, operation and control of the membrane processes.

Scientists were able to efficiently clean different membrane modules by rinsing them with water, then cleaning them with active chlorine or enzymes. Both methods result in a complete recovery of the original membrane resistance.

Further information. Cees De Kruif, NIZO-Netherlands Institute for Dairy Research, Kernhemseweg 2, PO Box 20, NL-6710 BA Ede, The Netherlands; phone: [phone]; fax: [phone].