An egg is a pre-packed food that is vulnerable to external microbiological loads, and is the major cause of Salmonella food poisoning in man. The mechanical protection afforded by the eggshell barrier and the antibacterial properties of membranes and egg white are influenced by several factors. These include physiology, genetics, the housing system of the hen and the storage conditions of the egg. Together they determine the potential infectious risk for humans.
This project aims to guarantee the safety and quality of eggs to consumers in new production systems, respective of hen welfare and to improve European Union competitiveness, favouring employment.
The objective is to optimise the quality and safety of table eggs in new production systems aiming at improving the welfare of hens. This will be achieved by understanding the factors that cause variation and by reinforcing the natural defence of eggs, which prevent bacterial penetration and growth. It is proposed to:
1) evaluate the new production systems (which will replace conventional battery cages in Europe by 2012) for egg quality and bacterial contamination
2) model the risk of bacterial contamination in the old and new housing systems, considering the changes in egg quality due to physiology, genetics and storage conditions
3) improve the egg's natural defence by understanding the origin of eggshell defects and by selecting hens for high eggshell quality (using marker assisted selection), and high antibacterial egg white activity by conventional selection
4) develop novel, real-time, non-invasive systems for grading eggs that will eliminate eggs with potential risks for the consumer.
Progress to Date
The project is progressing well.
1) Bacterial counts on eggs, as well as the proportion of cracked eggs, were significantly higher (though generally low) in furnished cages compared to the conventional ones. A higher proportion of dirty eggs in furnished cages was sometimes, but not always, reported. Important differences were observed from one manufacturer to another.
2) Using the agar approach, up until now no correlation between eggshell characteristics (except for porosity), or hen age and bacterial penetration was observed. Storage temperature, not relative humidity, directly influenced the initial rate of contamination. The final contamination was not affected. A predictive model of Salmonellae growth in eggs was developed using the Discrete approach.
3) The probability of bacterial growth in egg white increased when temperature, pre-storage time and, to a lesser extent, hen age increased. Results were different upon CO² storage. Haugh units were dependent upon storage conditions and age whereas among egg components, only the vitelline membrane protein VMOII was affected by pre-storage time.
4) Bacteriostatic and bactericide effects of egg white on Salmonellae and Staphylococci respectively were in evidence but showed no or low correlation with lysozyme (ELISA measurement) and protein contents.
5)The genes coding for the candidate proteins that may affect eggshell biomineralisation and quality, their regulation, as well as the specificity of these proteins tissue expression were studied.
6) Genomic DNA has been prepared and a large proportion of the phenotypic data collected from 2 066 hens.
7) A non-destructive optical measurement system was developed to assess egg freshness. Low resolution 1H-NMR parameters were optimised for assessing egg quality.
8) Four potential critical points for moisture development were identified in the French egg supply chain: early after laying, transfer from farm to packaging station, transfer from one packaging station to another, on the shelves. An inquiry was conducted during spring 2003 in French shops. The main conclusion was that current management practices are very loose (i.e. temperature, best-before date).
9) The egg defence website was launched and an education package has been initiated.
ANIMALS, HUMAN HEALTH AND WELLBEING
Scientist responsible for the project
Mr YVES NYS
CENTRE DE RECHERCHES DE TOURS
France - FR
Phone: +33 2 47 42 78 57
Fax: +33 2 47 42 77 77
||INSTITUT NATIONAL DE LA RECHERCHE AGRONOMIQUE
||01 October 2001
||3 604 397 €
|Total EC contribution
||2 642 779 €
|Web address of the project
- CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS, Spain - ES