Adhesion behaviors of egg white proteins to stainless steel (SS) surfaces at pH 7.4 and 30°C are reported. Ovalbumin and ovomucoid, acidic egg white proteins, were less adsorbed in the presence of phosphate (Pi), a multivalent anion, than in the presence of HEPES, an amphoteric ion. In contrast, lysozyme, a basic egg white protein, was more adsorbed in the presence of Pi than in the presence of HEPES. Citrate, another multivalent anion, and taurin, another amphoteric ion, affected the adsorption of these egg white proteins in a manner similar to Pi and HEPES, respectively. Based on the knowledge thus far obtained on the adhesion mode of several proteins to SS surfaces, these observations can be explained by assuming that small ionic substances precede proteins in attaching to SS surfaces, resulting in the alteration of effective surface charge. These findings could lead to the development of strategies for suppression of acidic egg white protein adhesion.
Hen egg is a nutritious food and a major source of biologically active compounds that are beneficial for human health. Proteomic technology has the power to monitor the protein composition of foods and changes in protein composition during the production and storage processes. Molecular changes in egg white proteins during storage have been investigated using two-dimensional electrophoresis coupled with mass spectrometry. The appearance and degradation of protein spots and shifts in isoelectric points of protein spots were observed during storage at 40°C for 7 days. These results support the use of proteomic profiling as a valuable tool for understanding the properties of egg white.