A simple method for isolating chicken egg yolk immunoglobulin using effective delipidation solution and ammonium sulfate.

Chicken egg yolk immunoglobulin (IgY) is a superior alternative to mammalian immunoglobulin. However, the practical application of IgY in research, diagnostics, and functional food is limited due to complex or time-consuming purification procedures. The objective of this study was to develop a simple, safe, large-scale separation method for IgY from egg yolk. Egg yolk was diluted with 6-fold delipidation solutions made of different types (pectin, λ-carrageenan, carboxymethylcellulose, methylcellulose, and dextran sulfate) and concentrations (0.01, 0.05, 0.1, 0.15, and 0.2%) of polysaccharides, respectively. The yolk solution was adjusted to pH 5.0, and then kept overnight at 4°C before being centrifuged at 4°C. The resulting supernatant was added to 35% (w/v) (NH4)2SO4 and then centrifuged. The precipitant, which contained IgY, was dissolved in distilled water and then dialyzed. SDS-PAGE and Western blotting were utilized to conduct qualitative analysis of IgY; high-performance liquid chromatography (HPLC) was used for quantitative analysis. The immunoreactivity of IgY was measured by ELISA. The results showed that yield, purity, and immunoreactivity varied with types and concentrations of polysaccharides. The optimal isolation of IgY for pectin, λ-carrageenan, dextran sulfate, and carboxymethylcellulose was at the concentration of 0.1%; for methylcellulose, optimal isolation was at 0.15%. The best results were obtained in the presence of 0.1% pectin. In this condition, yield and purity can reach 8.36 mg/mL egg yolk and 83.3%, respectively, and the negative effect of IgY on immunoreactivity can be minimized. The procedure of isolation was simplified to 2 steps with a higher yield of IgY, avoiding energy- and time-consuming methods. Therefore, the isolation condition under study has a great potential for food industry production of IgY on a large scale.