Functional Properties of Phosphorylated β-Lactoglobulin

Abstract

β-Lactoglobulin phosphorylated with phosphorus oxychloride yielded a protein containing 13 moles of phosphorus per monomer of β-lactoglobulin. A 6% weight/volume solution of the phosphorylated protein at pH 5 gelled upon dialysis against 100mM calcium2+. Emulsions prepared with the phosphorylated derivative were up to 30% more stable at pH 7 and pH 5 compared with corresponding emulsions prepared with native β-lactoglobulin. Emulsions (40% weight/weight corn oil) prepared in the absence or presence (1 to 5mM) of calcium2+ and at pH 5 or pH 7 with phosphorylated β-lactoglobulin or native β-lactoglobulin as emulsifiers varied in their creaming stabilities. As little as 1mM calcium2+ decreased creaming stability of emulsions prepared with the phosphorylated protein but increased creaming stabilities of emulsions prepared with native β-lactoglobulin. At 5mM calcium2+, pH 7, creaming stabilities of emulsions were similar for both protein emulsifiers, whereas at pH 5 the creaming stability of emulsions containing phosphorylated β-lactoglobulin was slightly higher. Viscosity of an emulsion (65% weight/weight corn oil, pH 5) prepared with phosphorylated β-lactoglobulin was about double that prepared with native β-lactoglobulin and similar to commercial mayonnaise.