Assessment: Shelf-life of Norwegian Eggs

This is the conclusion of an assessment carried out by the Norwegian Scientific Committee for Food and Environment (VKM).

Background

The European Food Safety Authority (EFSA) assessed the shelf-life of table eggs in 2014, and EU legislation currently sets a maximum shelf-life of 28 days. The Norwegian Food Safety Authority asked VKM to assess shelf life under Norwegian conditions to determine whether a longer shelf life may be permitted for Norwegian eggs.

Conclusions

"We have concluded that the scientific basis for EFSA’s 28-day shelf-life limit does not necessarily apply under Norwegian conditions,” says Taran Skjerdal, who led the work in VKM.

EFSA based its assessment on the high prevalence of Salmonella Enteritidis and vertical transmission, meaning that Salmonella can be transferred from the hen directly into the egg before the shell is formed. However, this is not applicable to Norwegian production. Surveillance shows an extremely low prevalence of Salmonella in Norway, and vertical contamination (transmission from hen to egg before laying) can be ruled out. Other aspects of EFSA’s assessment, such as degradation of egg barriers, temperature effects, enzyme activity, and spoilage organisms, remain relevant.

Other pathogens besides Salmonella are rare in Norwegian egg production and will not grow because of storage temperatures and the egg’s natural defense mechanisms. The data on antimicrobial resistance (AMR) are limited, and there are no Norwegian findings indicating AMR transmission via eggs.

Norwegian consumer behaviour is similar to European patterns, but Norwegians tend to store eggs longer. Nevertheless, the occurrence of egg related illness is very low.

“Raw, non–heat treated eggs stored at ≤12°C pose no health risk before day 35, which is Norway’s current shelf-life limit. Microorganisms that may enter the egg cannot grow due to low temperature, high pH in the egg white, and strong enzymatic antimicrobial activity,” says Skjerdal.

Methods

A qualitative methodology was used, combining:

• Review of EFSA’s 2014 assessment and identification of underlying assumptions.

• Literature searches for bacterial contamination, enzyme activity, spoilage bacteria, and antimicrobial resistance.

• Analysis of consumer behaviour data from the SafeConsume project, including 954 Norwegian respondents.

• Predictive microbiology based on known growth/no growth limits for microbes relevant to Norwegian produced eggs at temperatures of 12°C or lower and at egg white pH during storage.

VKM also assessed:

• Stability of egg barriers (cuticle, shell membrane, vitelline membrane) over time.

• Factors enabling horizontal contamination from shell to egg interior.

• Differences in risk profiles for Salmonella, Campylobacter, Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus.

The work in VKM was carried out by the Panel on Biological Hazards.

About VKM

VKM provides independent scientific assessments on matters relevant to environmental and food safety. VKM does not give advice or decide how risks should be managed but can evaluate the consequences of different actions. Decisions on risk management are made by the commissioning authority.