Improved emulsifying properties of beta-lactoglobulin by conjugating with carboxymethyl dextran

Bovine beta-lactoglobulin (beta-LG)-carboxymethyl dextran (CMD) conjugates could be prepared by using water-soluble carbodiimide. Two beta-LG-CMD conjugates were obtained, which maintained retinol-binding activity as strong as that of native beta-LG and had good emulsifying ability at neutral pH. The emulsifying properties of these beta-LG-CMD conjugates were investigated under various conditions by evaluating the stability of oil/water (O/W) type emulsions prepared with oleic acid and beta-LG-CMD conjugates. By conjugating with CMD, the emulsifying ability of beta-LG was greatly enhanced in the acidic pH range in the presence of NaCl <0.2 mol/dm(3). After heating at constant temperature (40-80 degrees C) for 10 min, the emulsifying ability of the beta-LG-CMD conjugates was higher than. that of beta-LG under all heating conditions. beta-LG-CMD conjugates are thought to be valuable as O/W emulsifiers.