Economic and Simple Purification Procedure for the Large-Scale Production of Ovotransferrin from Egg White

The objective of this study was to develop a simple and economical protocol for separating ovotransferrin from egg white. Egg white was separated from the yolk and diluted with the same volume of distilled water. To prevent denaturation during the separation process, ovotransferrin in 2x-diluted egg...

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Bibliographic Details
Published in:Poultry science 2008-07, Vol.87 (7), p.1441-1450
Main Authors: Ko, K.Y, Ahn, D.U
Format: Article
Language:English
Subjects:
Animals
Chickens
Chlorides
citric acid
Conalbumin - chemistry
Conalbumin - metabolism
denaturation
Egg White - chemistry
egg yolk
ethanol
Ethanol - chemistry
extraction
ferric chloride
Ferric Compounds - chemistry
Hydrogen-Ion Concentration
ion exchange resins
iron
Iron - chemistry
Iron - metabolism
new methods
ovalbumin
Protein Binding
purification
Resins, Synthetic
sodium bicarbonate
sodium chloride
solvents
transferrin
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Summary:The objective of this study was to develop a simple and economical protocol for separating ovotransferrin from egg white. Egg white was separated from the yolk and diluted with the same volume of distilled water. To prevent denaturation during the separation process, ovotransferrin in 2x-diluted egg white was converted to its holo-form by adding 20 mM FeCl₃·6H₂O solution (0.25 to 3 mL/100 mL). The pH of egg white was adjusted to pH 7.0, 8.0, or 9.0, and NaHCO₃ and NaCl were added to 50 mM and 0.15 M, respectively (final concentrations) to facilitate iron binding to ovotransferrin. The iron-bound ovotransferrin was separated from the egg white using different concentrations of ethanol (30 to 50%). Ethanol at 43% (final concentration) and pH at 9.0 were the best conditions for separating iron-bound ovotransferrin from 2x-diluted egg white solution. Almost all egg white proteins including ovalbumin were precipitated at 43% ethanol, but most of the iron-bound ovotransferrin remained in the supernatant. Holo-ovotransferrin in the 43% ethanol solution started to precipitate as the concentration of ethanol increased, but the optimal condition for precipitating ovotransferrin was when the ethanol concentration reached 59% (final). The precipitated holo-ovotransferrin was dissolved with distilled water, and AG1-X₂ ion exchange resin (at 3x iron content in ovotransferrin) was used to remove iron bound to ovotransferrin after pH adjustment to 4.7 using 500 mM citric acid. The apo-ovotransferrin obtained using this protocol was >80% in purity and around 99% in yield. The protocol developed is simple, economical, and appropriate for a large-scale production of ovotransferrin from egg white. Also, the isolated ovotransferrin can be applied in human foods, because the only solvent used in this process is ethanol. Furthermore, the AG1-X₂ ion exchange resin and ethanol used in this process can be regenerated and recovered.
ISSN:0032-5791
1525-3171
DOI:10.3382/ps.2007-00434