The use of total aerobic and Gram-negative flora for quality assurance in the production chain of consumption eggs

Washing eggs in sterile plastic bags with diluent is an efficient sample preparation method for the determination of the bacterial contamination on eggshells. The total count of aerobic bacteria and the total count of Gram-negative bacteria on the eggshell can be used to detect critical contamination points in the egg production chain. The number of eggs to be sampled in a point of the production chain was determined on a statistical basis and fixed on 40 for non-graded eggs and on 20 for graded eggs. In two production chains, one cage production and one organic production system, critical contamination points were identified. The most critical point for the cage production system was the metal mat at the start of the grading, candling and packaging machine, for the organic production system it was the initial contamination in the nest boxes. With the exception of heavily soiled shells, like shells from eggs collected from the ground (ground eggs), there is a poor correlation between the level of bacterial contamination and the visual eggshell contamination. A positive correlation was found between the initial bacterial eggshell contamination and the concentration of bacteria in the air of the poultry houses.