Improved Approaches to Separate High-Value Phospholipids from Egg Yolk

• Author / Creator

  Navidghasemizad, Sahar

• Egg yolk contains approximately 10% (w/w) phospholipids (PL), of which
  about 70% is phosphatidylcholine (PC). Conventional methods of PL extraction
  from egg yolk involve using hazardous organic solvents. Supercritical carbon
  dioxide (SC-CO2), as a "green" solvent, had been applied for the extraction of PL
  from egg yolk but resulted in limited success due to low recovery and purity of
  the final extracted PL. Hydrolysis of egg yolk after soluble proteins removal, referred to as pellet, by a combination of protease and Lipase AY30 reduced emulsion stability evident by larger oil droplets size and higher coalescence index. A cream fraction
  obtained from Protease P and Lipase AY30 treated egg yolk pellet was subjected
  to PL extraction using SC-CO2 in the presence of 8% ethanol as a co-solvent. The enzymatic treatment with Protease P and Lipase AY30 significantly improved the
  recovery of PC from 47% in dry yolk to 85%, 70% and 61% for dry, intermediate-moisture cream (20%), and “as is” cream (45% moisture), respectively, based on initial yolk weight. A higher purity of PC and PL (84% and 103%) was obtained by using hydrolysed pellet with the intermediate moisture content (20%), compared to dried egg yolk sample. Low-density lipoproteins (LDL) contain about 90% of PL from egg yolk. Possible interaction between egg yolk components and polysaccharides can be a
  potential technique for LDL separation. A simple method was proposed to isolate
  LDL from egg yolk using 0.2% to 0.6% xanthan gum at egg yolk natural pH. The
  mechanism of LDL separation with xanthan gum was suggested to be a
  combination of different interactions such initial electrostatic and hydrophobic
  forces and physical properties of the polysaccharide and its complex with egg
  yolk LDL such as shear thinning behaviour of xanthan gum solution and density
  difference of LDL-xanthan gum complexes. PL is a high-value component from
  egg yolk with potential applications in pharmaceutical and nutraceutical
  industries. Developing methods to improve the recovery and purity of PC and PL
  from egg yolk while eliminating hazardous organic solvents use will help to
  protect the environment and enhance food safety.

• Subjects / Keywords

  • Yolk
  • Phospholipids
  • Low denisty lipoprotein
  • Polysaccharides
  • Supercritical carbon dioxide
  • Extraction
  • Emulsions
  • Phosphatidylcholine

• Graduation date

  Spring 2013

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3JQ02

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.