Moisture impact on extractability of phospholipids from leftover egg yolk after enzymatic treatment using supercritical carbon dioxide

• Phospholipids from egg yolk were extracted using supercritical CO2 + ethanol.
• Enzymatic hydrolysis improved phospholipid recovery from egg yolk.
• Phospholipid recovery decreased at higher moisture content.
• Highest purity of extract was for 20% moisture cream and fresh egg yolk.

The leftover egg yolk after immunoglobulin Y (IgY) extraction was subjected to enzymatic hydrolysis with Protease P and Lipase AY30, which resulted in the formation of cream. The extractability and purity of phosphatidylcholine (PC) and total phospholipids (PL) at three levels of moisture content in cream (freeze dried cream, 20% and 45%, w/w) were studied using supercritical carbon dioxide (SC-CO2) extraction with ethanol addition (8%, mole%) as co-solvent at 48.3 MPa and 70 °C. The results were compared to those obtained from fresh yolk and dry yolk. The highest recoveries of PC and total PL were for freeze-dried cream and cream with 20% moisture in which the recovery of PC was about 85% and 65%, respectively, based on the initial mass of yolk used for cream formation and 94% and 106% recovery, respectively, based on the amount of cream used as extraction feed. The highest purity of PC was about 87% obtained from fresh yolk and 84% from cream with 20% moisture content. This study showed that enzymatic treatment of the pellet can improve the recovery of PC and PL from egg yolk at moisture contents of up to 20%.