Research advances on the effects of thermal and non-thermal processing techniques on the physicochemical properties and microbiological control of liquid eggs

Eggs are often hailed as "the ideal nutrient reservoir for human beings", however, due to the problems of fragility, transportation, and storage of shell eggs, and the tendency to carry foodborne pathogens (Salmonella, Listeria monocytogenes, Escherichia coli), liquid eggs have gradually become a substitute for shell eggs. Pasteurization is a common international method of thermal processing method for liquid eggs. While pasteurization ensures the microbiological safety of liquid eggs, it may also negatively affect the organoleptic and functional properties of liquid eggs, such as reduced emulsification, foaming, or gelling properties. Additionally, pasteurized liquid eggs are constrained to a storage period of 2-3 weeks at 4 degrees C. To overcome these drawbacks, new processing methods are gradually being adopted for liquid eggs, such as high pressure treatment, ultrasound and ultraviolet light, etc. These methods not only exhibit the capability to effectively eradicate foodborne pathogens and further extending the shelf life of liquid eggs, but also uphold the physicochemical integrity of liquid eggs. Remarkably, they even hold the potential to enhance functional attributes. In light of these advantages, they present themselves as compelling alternatives to traditional pasteurization. This comprehensive review critically assesses the ramifications of diverse processing approaches (including thermal and non-thermal) on microbial content and physicochemical properties of liquid eggs in the egg industry. Emphasis rests on elucidating the mechanisms underlying non-thermal processing techniques and delineating their current research landscape. The ultimate aim is to equip the egg industry and researchers with insights to judiciously select the most fitting liquid egg treatment modality.