One-step separation from lactose: recovery and purification of major cheese-whey proteins by hydroxyapatite--a flexible procedure suitable for small- and medium-scale preparations

The recovery of cheese-whey proteins and lactose represents an important task both in environmental and in food sciences. Optimization of whey processing requires the quantitative separation of whey proteins from lactose, lower costs, harmless environmental impact, flexibility in protein recovery, and adaptability of the process to type and amount of available whey. Here we present a method based on the use of self-made, low-price, and nontoxic hydroxyapatite for one-step separation of lactose (non adsorbed) from bovine whey proteins (adsorbed). Recovery of proteins can be performed with high flexibility. Total protein fraction can be eluted with 0.4 M phosphate at pH 7.0. In alternative, proteins can be recovered in pairs with 0.4 M phosphate but at different pH's. About 56% of the proteins, primarily alpha-lactalbulmin and IgG, were eluted at pH 5.0. The other major proteins, beta-lactoglobulin and BSA, were eluted at pH 6.0. Fractions eluted with the two first eluants at pH 5.0 and pH 6.0 were applied to a Superdex 75 column for final purification by gel filtration. This method provides flexibility in whey protein recovery and quantitative separation of proteins from lactose before ultrafiltration and nanofiltration.