Functional Properties of Phosphorylated β-Lactoglobulin

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Abstract
.beta.-Lactoglobulin phosphorylated with phosphorous oxychloride yielded a protein containing 13 mol P/monomer of .beta.-lactoglobulin. A 6% wt/vol solution of the phosphorylated protein at pH 5 gelled upon dialysis against 100 mM Ca2+. Emulsions prepared with the phosphorylated derivative were up to 30% more stable at pH 7 and 5, compared with corresponding emulsions prepared with native .beta.-lactoglobulin. Emulsions (40% wt/wt corn oil) prepared in the absence or presence (1-5 mM) of Ca2+ and at pH 5 or 7 with phosphorylated .beta.-lactoglobulin or native .beta.-lactoglobulin as emulsifiers vaired in their creaming stabilities. As little as 1 mM Ca2+ decreased creaming stability of emulsions prepared with the phosphorylated protein but increased creaming stabilities of emulsions prepared with native .beta.-lactoglobulin. At 5 mM Ca2+, pH 7, creaming stabilities of emulsions were similar for both protein emulsifiers; at pH 5 the creaming stability of emulsions containing phosphorylated .beta.-lactoglobulin was slightly higher. Viscosity of an emulsion (65% wt/wt corn oil, pH 5) prepared with phosphorylated .beta.-lactoglobulin was about double that prepared with native .beta.-lactoglobulin and similar to commercial mayonnaise.