Isolation of immunoglobulin from egg yolk by anionic polysaccharides

Isolation conditions of immunoglobulin in egg yolk (IgY) were optimized by the addition of various levels of Na-alginate (Alg), lambda-carrageenan (lambda-Cg), Na-carboxymethyl cellulose (CMC), and pectin (PC) to 6-fold diluted yolk. The mixtures were then reacted at pH 4.0-6.0 for 30 min. The optimal isolation conditions of IgY for Alg, lambda-Cg, and CMC were at the 0.1% level and at pH 5.0, while those for PC were at the 0.15% level and at the same pH. The remaining lipid and remaining protein in the supernatants thus obtained was 0.5-3.8% and 10-17%, respectively, and more than 90% of lipoproteins were precipitated. The IgY recovery was determined to be 33-74% by means of single radial immunodiffusion method when IgY was isolated under the optimal conditions. PC showed the best recovery of IgY, while lambda-Cg provided the least. The interactions between polysaccharides and lipoproteins were mainly ionic bonds, hydrophobic interactions, and hydrogen bonds as determined by the addition (0-2.0 M) of NaSCN or urea to the polysaccharide-lipoprotein precipitates.