J Am Oil Chem Soc (2014) 91:1857–1866 DOI 10.1007/s11746-014-2542-y 1 3 ORIGINAL PAPER Destabilization of Egg Yolk Emulsion After IgY Removal Through Enzymatic Treatments Sahar Navidghasemizad · Alexandra Acero-Lopez · Jonathan Curtis · Feral Temelli · Jianping Wu Received: 29 March 2013 / Revised: 17 March 2014 / Accepted: 7 September 2014 / Published online: 30 September 2014 © AOCS 2014 environmentally-friendly techniques such as supercritical carbon dioxide (SC-CO 2 ) extraction. Keywords Egg yolk pellet · Enzymatic treatment · Emulsion · Phospholipids Introduction Hen egg yolk is widely used in the food industry due to its excellent emulsifying properties. Egg yolk contains about 50 % solids, composed mainly of lipids and proteins at a ratio of about 2:1 [1]. On a dry matter basis, egg yolk typi- cally contains 68 % low density lipoproteins (LDL), 16 % high density lipoproteins (HDL), 10 % livetins and 4 % phosvitin [1]. The liquid egg yolk at its natural pH can be separated into two distinct fractions: granules and plasma using ultracentrifugation [1] or through twofold water dilu- tion [2, 3]. Plasma contains about 77–81 % of the egg yolk dry matter and is composed of 73 % lipids, 25 % proteins and 2 % ash. The major constituents of plasma are LDL (85 %) and livetins (15 %). Granules make up 19–23 % of egg yolk dry matter and are composed of 70 % HDL, 16 % phosvitin and 12 % LDL (LDLg) [2]. Immunoglobulin Y (IgY), also called γ-livetin, a water- soluble protein, is an alternative to a mammalian antibody that can be used as a nutraceutical ingredient or an alter- native to antibiotics [4]. IgY was separated using a simple tenfold water-dilution from egg yolk as described by Kwan et al. [5]. At pH 6 and tenfold water dilution, about 90 % of IgY remained in the supernatant aqueous phase while over 90 % of lipids precipitated into the granules and formed the pellet fraction [5, 6]. Fresh egg yolk contains approxi- mately 10 % (w/w) phospholipids (PL), of which about 80 % are choline derivatives [7]. Choline, an essential Abstract The objective of this study was to destabilize the protein–lipid complex in egg yolk precipitate obtained after the removal of soluble proteins, referred to as the pel- let, through enzymatic treatment for further phospholip- ids extraction. A combination of proteolytic and lipolytic enzymes was applied to release the lipids from the pellet or weaken the pellet emulsion. Emulsions prepared using Protease P/Lipase AY30, Protease II/Lipase AY30 and Pro- tease M/Lipase AY30 treated pellets had larger oil droplets (78, 65, 56 μm) and higher coalescence rates (51, 41, 35 %) than those of Protex 51FP, pellet, Protex 7L and Protease A with oil droplet size of 20, 18, 15 and 13 μm and coales- cence rates of 31, 8, 7.5 and 8 %, respectively. Cream and liquid subnatant fractions obtained after further centrifuga- tion of hydrolysates were subjected to lipid analyses. Over 90 % of phosphatidylcholine (PC) present in the pellet and 80 % of that in the original egg yolk were recovered in the cream from Protease P/Lipase AY30 treatment, while the recovery of PC from the egg yolk was significantly lower in creams from Protex 7L or Protease 51FP treatments (12 and 10 %, respectively). Pellets treated with Protease M, Protex 7L or Protex 51FP in combination with Lipase AY30 led to a significant loss of PC due to the conversion of PC to lysophosphatidylcholine or its degradation. Cream fractions obtained from the study represented a better material for the recovery of PL than intact egg yolk using S. Navidghasemizad · A. Acero-Lopez · J. Curtis · F. Temelli (*) · J. Wu (*) Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G2P5, Canada e-mail: feral.temelli@ualberta.ca J. Wu e-mail: jwu3@ualberta.ca