Egg yolk consists of a soluble fraction (called plasma) and an insoluble fraction (called granules) containing large particles 7. In contrast, egg yolk is rich in lipoproteins, which are lipid-protein complexes. Other proteins in egg white include ovotransferrin (conalbumin), ovomucoid, lysozyme, and ovomucin 7. Approximately half of the protein content of egg white is ovalbumin 7. The egg white and yolk contain several proteins with diverse structures 6. Therefore, the development of pasteurized frozen whole egg products with properties similar to those of unpasteurized whole eggs has been an important issue in food science and industry.Ī hen egg consists of a shell, egg white, and yolk. For example, these changes can result in a decrease in the foaming ability of eggs when making sponge cakes as well as a decrease in heat aggregation when making egg soup 3, 4, 5. However, temperature changes owing to pasteurization, freezing, and thawing can cause changes in the properties of hen eggs. The frozen products are thawed before used in cooking. The process is usually followed by rapid freezing to produce pasteurized frozen whole hen egg products. Pasteurization, typically at ~ 60 ☌, is performed to kill Salmonella spp., Escherichia coli, and other bacteria in eggs, as high-temperature sterilization causes thermal denaturation of egg proteins 2. Processed hen eggs that have been pasteurized and frozen can be stored for long periods and are widely used in cooking and the production of confectionery 2. Hen eggs are rich in proteins and are an important source of protein for humans 1. Additionally, they may be useful in determining molecular sizes and shapes of multiple components in various complex biological systems such as whole eggs. The results suggest that SEC and SEC-SAXS can be used to differentiate between unpasteurized and pasteurized frozen whole eggs. We found that proteins in the plasma fraction of egg yolk, especially apovitellenins I and II, formed large aggregates in the pasteurized eggs, indicating that their structures are sensitive to temperature changes during pasteurization, freezing, and thawing. In this study, size-exclusion chromatography (SEC) and SEC coupled with small-angle X-ray scattering (SEC-SAXS) were successfully used to differentiate between the proteins in unpasteurized and pasteurized frozen whole eggs. To develop pasteurized frozen whole egg products with properties similar to those of unpasteurized whole eggs, it is necessary to establish a method that can differentiate between the two egg types with respect to the structures of their proteins. However, processed eggs differ from raw eggs in properties such as viscosity, foaming ability, and thermal aggregation. Pasteurized frozen whole hen eggs are widely used in cooking and confectionery and can be stored for long periods. Hen eggs are rich in proteins and are an important source of protein for humans.
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