Proteomic measures of albumen degradation as indicators of egg freshness

Abstract

With prolonged storage especially at elevated temperatures, thick albumen deteriorates as it loses its viscous characteristics and this is regarded as a sign of reduced egg freshness and quality. Currently, HU is a widely used procedure for determining albumen quality. Proteomic analysis of egg albumen changes could provide a comprehensive understanding of egg freshness and used to assess egg quality during storage and processing. A core objective of this research was to identify and quantify proteins that change during albumen degradation with the potential to identify novel biomarkers of egg freshness and quality. The first efforts of identifying the protein changes in albumen used 2D-PAGE. The changes in albumen proteins were obvious after just 7d of storage at room temperature and this fitted with the more pronounced changes observed using conventional measures of egg quality. The N-TAILS approach to identifying protein changes in egg albumen was instigated and a number of antibacterial proteins were identified. Lysozyme C was identified in all samples. Lysozyme C changes associated with albumen degradation provides a potential biomarker of albumen quality and by association egg aging. The second objective of the project was to evaluate egg quality from different production systems. In retrospect, such an evaluation would have little relevance if some of the other factors such as hen age, ambient temperature and acute stress, could not be accounted for. After accounting for these there was no differences in the deterioration of egg quality during storage at commercial cool room conditions for eggs collected from free range or conventional cage production systems.