Ultrafiltration modes of operation for the separation of α-lactalbumin from acid casein whey

Whey is a complex protein mixture which contains two major proteins (beta-lactoglobulin, alpha-lactalbumin), the size of which are close to each other. The separation of alpha-lactalbumin by membrane processes can be made more performing by the appropriate selection of the operation mode. The equations of the models for continuous, discontinuous concentration or diafiltration (single or combined) are developed. They show that performances (purity, yield) depend on initial purity (initial feed), on transmission (membrane and operating conditions) and on the operation mode. Simulations and experimental concentration and diafiltration operation modes are in good accordance. They show that continuous concentration up to a high volume reduction ratio (11-15) or a combined continuous concentration-diafiltration helps to obtain a fraction with both an enhanced purity and a satisfactory yield of alpha-lactalbumin in the permeate. (C) 1999 Elsevier Science B.V. All rights reserved.