This guide advises on the safe use and handling of eggs for catering establishments. Eggs are an important food source, with over 27 million eggs being eaten every day in the UK alone. It is however important to know and respect their limitations. To subject an egg to inappropriate conditions could reduce both its quality and its natural defences and ultimately put human health at risk.

Salmonella and eggs

It is commonly accepted that salmonella bacteria can contaminate eggs. The bacteria commonly originate from infected birds that pass the salmonella from their intestines to the egg as it develops inside the bird.

In addition bacteria on the outside of dirty eggshells may contaminate the egg contents when the shell is broken or, under favourable conditions, migrate through the shell and into the contents. Once inside the bacteria are able to grow rapidly, using the nutritious contents as a food source.

Hence, it is important to protect eggs from external contamination. They should not be stored next to or below raw meat so as to protect against contamination of the shell with bacteria which could then migrate through the shell, or contaminate the contents when the shell is broken.

Eggs and natural protein

Eggs do have an invisible protective barrier around the outside of the shell that acts to prevent the migration of salmonella and other bacteria from the environment into the egg. Once the egg has been refrigerated or stored above 20 degrees C condensation is formed and the moisture destroys this natural barrier. Bacteria can then pass easily through the shell and into the egg. For this reason once an egg has been refrigerated it must be kept refrigerated until used. This explains why supermarkets can sell eggs at ambient temperature. Plus the turnover at supermarkets is so high that the time from being laid to sold is minimal.

Storage and use of eggs

Despite having this natural barrier that is destroyed once refrigerated it is still recommended that eggs be refrigerated once purchased. This is because the barrier does gradually lose efficiency with time, and also keeping eggs below 8 degrees C will reduce the speed at which any salmonella that are already inside the egg, from the bird, will multiply.

Since bacteria in the egg will multiply, albeit at a slower rate if refrigerated, they cannot be kept indefinitely. Eggs should always be sold within 21 days of being laid and used within 28 days of being laid.

The practice of 'breaking out' is not recommended at all, but if you feel you must, the 'broken out' egg must be refrigerated until needed. For example, whisking a number of eggs and then leaving them in a bowl by the cooking range to allow omelettes to be made quickly to order. Once broken, the egg is vulnerable to external sources of contamination, existing bacteria will multiply readily in the nutritious medium and the warm temperatures by the cooking range will be perfect for rapid multiplication.

Caterers must only use intact Grade A eggs.

Damaged and dirty eggs

Eggs with cracked shells should never be used because of the potential for high levels of bacteria to have contaminated the egg through the crack. Any contamination on the outside of the egg should be wiped off with a clean dry cloth (remember, moisture destroys that protective barrier so use of a wet cloth should be avoided). If any contamination remains it should only be wiped off with a damp cloth directly before being used.

Cooking eggs

A large number of salmonella food poisoning outbreaks can be attributed to products made from raw or lightly cooked egg such as mayonnaise or meringue. Often these incidents are made worse because of incorrect handling and failures in temperature control. Eggs should always be cooked thoroughly. Where dishes necessitate the use of lightly cooked or raw egg the use of pasteurised egg products is recommended. These products can be bought as liquid or powder and as whole egg or just the yolk/white. Liquefied pasteurised egg must be kept refrigerated, as must the dried products once water has been added to them.

Summary

• Legislation requires that caterers only use grade A eggs.
• Eggs are fragile and should be handled carefully.
• Signs of damage should be investigated and broken eggs and soiled packaging disposed of properly.
• Eggs should not be washed or wiped with a damp cloth as this makes them more susceptible to contamination.
• Eggs should be stored in the refrigerator in their date labelled packs, if not marked on the shell.
• Eggs should be used within one and a half hours of removal from the refrigerator.
• Avoid repeatedly moving eggs from the refrigerator by only taking out what you need.
• Hands should be washed before and after handling loose shell eggs.
• Eggs are vulnerable to taint and should not be placed close to pungent foods and materials.
• A planned system of handling should ensure stock rotation.
• Broken out eggs, pasteurised liquid eggs and reconstituted dried egg must be refrigerated.
• Food hygiene training for staff should include attention to the correct handling of eggs and foods containing them.