Effect of operating conditions on the extraction of ovomucin

Abstract

Ovomucin, mainly responsible for the gelatinous property of egg white, has potential applications as a functional food and nutraceutical ingredient. A 2-step method for ovomucin preparation was recently developed. The purpose of this study was to determine the effects of various operating conditions, such as pH, NaCl concentrations and extraction volume at the second extraction, temperature, and centrifugation force, on the purity and yield of ovomucin. Our results showed that pH has a significant effect on the purity and yield of ovomucin extracts. Increasing the extraction pH from 4.0 to 5.0 could significantly ( p < 0.05) increase the purity and yield of ovomucin; at pHs higher than 5.0, the purity was not affected but the yield was significantly decreased. The highest yield of ovomucin extract (308 mg/100 g of egg white) was achieved at pH 5.0 while the highest purity was achieved at pH 7.0. There is a trend that the purity of ovomucin increased ( p < 0.05) but the yield of ovomucin decreased ( p > 0.05) at increasing salt concentrations. Reducing extraction volume did not affect the yield of ovomucin whereas its purity was significantly decreased. The yield of ovomucin however was significantly increased at increasing settling time or centrifugation force, but the purity was less affected. Extraction of ovomucin at room temperature could significantly reduce the extraction yield compared to that at lower temperature (4 °C) but the purity was not affected.