Extraction of IgY from egg yolk using a novel aqueous two-phase system and comparison with other extraction methods

Egg yolk is an important source of antibodies. The biggest obstacle for isolation of chicken antibodies (IgY) is the removal of lipids, which are present in abundance in egg yolk. We have used a two-phase system to separate egg yolk. The use of an aqueous two-phase system with phosphate and Triton X-100 made separation of lipids and water-soluble proteins possible. Lipids are extracted into the detergent-enriched top-phase, whereas IgY is isolated in the phosphate-enriched bottom-phase. The phosphate:triton system was characterised and optimised using various experimental designs. For the optimised model, the yield of IgY was kept above 97% (11.1-14.9 mg IgY/g egg yolk recovered). The amount of lipids in the bottom-phase was kept below 25% of the total content in the egg yolk added. Hence, the model described provides a method for extracting the IgY-fraction with a high yield and relatively low lipid content.