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Listen to this siteWednesday 25 June 2003
This research project will investigate the ability of egg washing to reduce the level of salmonella present on the shell.
Study Duration : October 2000 to January 2003
Contractor : Direct Laboratory Services Ltd
Egg washing is an established method of cleaning eggs and, at present, is only permitted for Class B and C eggs in the UK, under the Egg (Marketing Standards) Regulations 1995. There has been a significant amount of research into the effectiveness of egg washing which has suggested that it can result in eggs with a markedly reduced level of bacteria on the shell. However, a Government review in 1996 suggested that the egg washing systems available at the time required a number of technical improvements to ensure that the process could be carried out properly. This research was commissioned to determine what (if any) improvements had been made since the last report and to assess the ability of egg washing to reduce the level of salmonella present on the shell.
The objectives of the project are:
A government review of egg washing in 1996 suggested that the egg washing system available at the time required a number of technical improvements to ensure that the process could be carried out properly. This project was commissioned to determine what (if any) improvements had been made since the last report and to assess the ability of egg washing to reduce the level of salmonella present on the shell.
Spray washing
The data produced by this study have clearly shown that use of a commercial spray washer under ideal conditions, can cause 1 million-fold reduction to levels of shell surface salmonella. In addition, when spray washed under ideal blueprint conditions, there was no evidence that salmonella could be transmitted into the egg contents. A number of the parameters studied such as the age of the birds that laid the eggs, lowering of the spray wash jet pressure and lowering the concentration of washing detergent did not significantly influence removal of salmonella from the shell. The most important factor in reducing salmonella levels on the shell surface was maintenance of a temperature of >
40°C in the wash and rinse waters.
Bucket washing
The small-scale farm bucket washer was also effective at washing eggs and reducing bacterial levels under ideal conditions. However, the water became very dirty after a few batches of eggs had been washed. Washing in dirty water can increase the level of bacteria on the surface of the shell, although these bacteria were unable to penetrate into the egg contents.
Both the spray and bucket washing procedures caused damage to the surface of the eggshell, hence making it easier for the bacteria to penetrate the eggs but in practice this did not occur.
Industry opinions
A majority of the opinions expressed by the representatives from various organisations consulted was that egg washing is a positive practice if it improves egg hygiene. However there were concerns such as the cost and that egg washing could lead to an increase in contamination. The overall opinion was that egg washing was not particularly necessary.
The final report is available from the FSA Library and Information centre.
To obtain a copy, please contact the Enquiry Desk,
Dr Elsie Widdowson Library and Information Services, Food Standards Agency (tel: 020 7276 8181/8182) or email:
library&info@foodstandards.gsi.gov.uk
).
Contact
: For any enquiries concerning this research project, please contact the relevant Programme contact or email
science@foodstandards.gsi.gov.uk
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