Abstract: This work was carried out to investigate the effect of polyethylene glycol (PEG) molecular weight, PEG dosage and pH value of egg white on the precipitation rate of ovalbumin (OVA), ovotransferrin (OVT) and lysozyme (LYZ), and further to establish a new procedure for the separation of OVA from egg white. It was found that OVA, OVT and LYZ could be precipitated by PEG 4000, 6000, 8000 or 10000. In addition, the precipitation rate of OVA, OVT and LYZ was significantly influenced by PEG dosage and pH. By addition of 12% PEG and at pH 7.5, the maximum difference between the precipitation rates of OVA, OVT and LYZ was observed. This result was also obtained when pH was adjusted to 5.5. Therefore, OVA could be produced by the following procedure. PEG 4000 was added into egg white (pH 7.5) until its concentration reached 12%, and then the supernatant was collected after centrifugation as OVA with a recovery of 95.1% and a purity of 88.1%. The purity was increased to 99.7%, while the recovery was decreased to 87.3% by adjusting the pH to 5.5 and collecting centrifugal supernatant. This purification procedure was simple and easy to operate and could facilitate large-scale production and application of OVA in food and medicinal fields.

Key words: polyethylene glycol precipitation, relative molecular weight, ovalbumin, ovotransferrin, lysozyme