In this study, ion exchange chromatography was employed to prepare high-purity α-lactalbumin from whey protein powder obtained from raw cow’s milk by sequential membrane separation and spray drying. The results showed that α-lactalbumin constituted 21.04% of the true protein in the permeate obtained using a 50-nm pore-sized ceramic membrane with three-fold concentration, one cycle of microfiltration and two cycles of washing, which was higher than that obtained using a 100-nm pore-sized ceramic membrane (15.84%). The permeate was spray dried and separated by ion exchange chromatography. Good chromatographic separation of α-lactalbumin and β-lactoglobulin was achieved with increasing NaCl concentration from 0 to 0.5 mol/L at up to 10 column volumes, and 98.18% pure α-lactalbumin and 97.82% pure β-lactoglobulin were obtained. The results of this study provide support for the industrial preparation of high-purity α-lactalbumin.

The separation of ingredients from raw milk is an essential step during the production of dairy products. Membrane separation technology has been applied in the dairy processing industry for decades and has increasingly become indispensable in solving some problems such as separation, concentration, sterilization and in developing new dairy products. In this paper, the main applications of membrane separation technology in the dairy industry, including milk standardization, protein separation, whey desalination and waste water utilization are reviewed, in order to provide reference for process selection and optimization.