Research: Contamination in shell egg processing

Enterobacteriaceae, including Salmonellae, may be recovered from foods and processing facilities. High levels in the plant may be an indication for inadequate sanitation processes, or lack of hygiene during production.

Surfaces of equipment, packages and other objects in contact with foods are potential sources of contamination. Also, surfaces that do not come into direct contact are a potential reservoir of micro organisms.

Egg processing plants receive eggs which, during the previous phases of production and handling, have been in contact with different materials and equipments, which can be contaminated through flies, dust, faeces and rodents. Depending on the way of processing, in-line, where hen houses are physically connected to the processing plant, off-line processing or a mixed procedure, where in-line egg production is supplemented with off-line eggs, different transport vehicles are in use.

Off-line eggs are transported to the processing plant in plastic flats on metal carts with unpainted plywood shelves. During transport eggshells can crack and the contents can leak to the wooden shelves. These shelves then provide a perfect substrate for microbial growth as cleaning and disinfection is often not applied.

In this study it was determined whether nest carts may serve as a reservoir for Enterobacteriaceae. Samples were taken at three processing plants during several visits. Several genera, Salmonella, Escherichia, Citrobacter, Klebsiella, Hafnia and Enterobacter, were isolated, indicating the potential risk of spreading through these nest carts.

Source: Poultry Science 88 (2009)

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