Why do we in Europe not keep eggs in the fridge, but find them on the supermarket shelves?
Supermarkets in Europe do not keep eggs refrigerated. They keep them at room temperature, next to canned goods, sugar, flour and other foods with a long shelf life. This is different in the US, where eggs are kept in refrigerators, usually in the milk and dairy section. The different preservation requirements are the result of different practices in poultry farming and in the subsequent handling of eggs by producers.
In the United States, to reduce the risk of Salmonella contamination, eggs are washed and sprayed with chemical disinfectants before being released to consumers. This treatment removes potential Salmonella contamination, but at the same time destroys and removes the protective film surrounding the egg. This film acts as a protective layer that regulates the gas exchange between the internal and external environment of the shell. At the same time it acts as a first line of defence against bacterial invasion. Without the protective layer, the eggs cannot retain water and oxygen and are more susceptible to bacterial invasion. Therefore, clean eggs are kept at low temperatures to prevent rapid deterioration and prevent the growth of pathogenic bacteria.
In European Union countries, there is a different approach to controlling Salmonella contamination of eggs. Eggs are not washed and therefore do not need to be refrigerated. The main objective during egg production is to produce clean eggs in poultry farms, rather than requiring subsequent actions to disinfect them. This is achieved by proper management and controls in the poultry houses.
Because of these different approaches and legislative requirements on both sides, eggs produced in the U.S. could not be sold in the European Union, and vice versa.
Poultry farming and egg disinfection in the USA.
In America, large poultry farms are preferred over smaller producers of free range eggs. Egg factory farms can produce more eggs in a smaller space, but expose them to a greater risk of Salmonella contamination, even under good sanitary conditions. The bacteria can be transferred from an infected hen to the inside of the egg during its development, or can contaminate it after laying through contact of the egg with hen faeces.
To reduce the possibility of contamination, the eggs are immediately transported from the henhouse on conveyor belts which take them through a cleaning and disinfection array. It is very critical to clean the eggs properly, otherwise the process can even increase the possibility of contamination by bacteria through the feces that may surround them. Wetting the unclean eggshell creates the right moisture conditions in which bacteria can grow and favours their growth and their ability to penetrate the shell, resulting in contamination of the egg.
The USDA requires that eggs, after being disinfected, should be immediately transferred to refrigerated chambers at a constant temperature of 7.2 degrees Celsius. After cooling, however, the eggs should not be allowed to exceed this temperature, as a cold egg, if the temperature is raised, will cause sweating in the shell which will promote bacterial growth. For this reason, chilled eggs should not be left in different conditions for more than two hours.
Poultry farming and egg hygiene conditions in the European Union
In EU countries, washing of eggs is prohibited, as it would result in damage to the outer membrane that surrounds the eggs and protects the inside from bacteria.
Over the last two decades in the EU, in order to eliminate any possibility of Salmonella poisoning outbreaks, a strict vaccination programme has been implemented in the EU, which has not yet been applied with the same rigour in the USA.
In European countries, the main objective remains the prevention of Salmonella contamination of eggs at the production stage. In conjunction with the ban on cleaning, the observance of good production and hygiene practices in poultry farms is promoted. This has resulted in the eggs being kept at a temperature of between 17 and 23 degrees Celsius.
