Functional properties of beta-lactoglobulin phosphorylated in the presence of different aliphatic amines

Phosphorylation of beta-lactoglobulin was carried out with 20, 40 and 80 mot POCl3/mol protein in the presence of different aliphatic amines. The physicochemical properties of the modified proteins changed according to the nature of amine (tertiary or primary; shorter or longer aliphatic chain). The use of butylamine during the phosphorylation of beta-lactoglobulin with POCl3 resulted in a low phosphorylation yield (2-4 mol P/mol protein), conferring, however, excellent foaming and emulsifying properties to the phosphobutylated protein. The use of longer aliphatic primary amines (8-12 C) as bases and nucleophiles during the phosphorylation of beta-lactoglobulin gave rise to low phosphorylation, reduced solubility, poor foaming and emulsifying properties.