Abstract:

Milk basic protein (MBP) is one part of whey protein. It has been reported to suppress osteoclast-mediated bone resorption in vitro. In the present study, MBP was extracted from byproduct whey of Mozzaralla cheese making by ion exchange chromatography and the resultant crude extract was purified by polydextran gel chromatography. Four strongly acidic cation exchange resins were used to adsorb MBP, and D072 type resin was selected due to the highest adsorption capacity. Single factor and orthogonal array design methods were employed to optimize conditions (desorption flow rate, temperature and concentration of desorption solvent, phosphate buffer) for the desorption of MBP from D072 type resin. The results showed that desorption flow rate had the most significant effect on MBP desorption, followed by temperature and desorption solvent concentration. Their optimum values were found to be: desorption flow rate 2.50 mL/min, temperature 40 ℃ and desorption solvent concentration 0.04 mol/L. Under these conditions, a MBP yield of 7.55% was obtained. After the purification with Sephadex G-100 with 4000 － 150000 D separation scope, a MBP product with 83.55% purity was obtained.

Key words: milk basic protein, ion exchange technology, orthogonal array desing, polydextran gel chromatography