Method for purifying egg yolk immunoglobulins

A method for separating an IgG immunoglobulin from a yolk of an egg, comprising:

• (a) combining the egg yolk with an effective amount of an aqueous medium to provide an aqueous suspension of the egg yolk;
• (b) combining the aqueous egg yolk suspension with a nonionic detergent at a temperature of about -25.degree. C.-60.degree. C. and a pH of about 5.5-9.5 to form a mixture;
• the amount of the nonionic detergent effective to provide phase separation of the egg yolk phase;
• the nonionic detergent being substantially non-denaturing to the IgG immunoglobulin;
• (c) allowing the mixture to separate into an aqueous phase and a non-aqueous detergent phase wherein the aqueous phase contains a major portion of the IgG immunoglobulins of the egg yolk;
• and
• (d) separating the aqueous phase from the non-aqueous detergent phase, to provide an aqueous, substantially pure IgG immunoglobulin fraction.