The right way to store your eggs

Eggs have a steadfast place in our diets - from sunlit breakfasts of scrambled eggs and toast to towering birthday cakes. Yet one everyday question can stir more debate than you might expect: Should you refrigerate eggs or leave them out on the counter?

Should eggs be refrigerated?

The short answer: yes, in many cases. The longer answer: it depends on how and where the eggs were processed and how they're going to be stored.

In nations such as the United States, commercially sold eggs undergo washing and sanitising before reaching the store. This removes the natural protective cuticle on the eggshell, making the interior more vulnerable to bacterial penetration unless refrigerated. 

The United States Department of Agriculture (USDA) and the Food and Drug Administration (FDA) advise storing eggs in the fridge at 40 degrees F (4 degrees C) or below to minimise the risk of contamination. 

A study published on ResearchGate looked at the effect of storage temperature on egg quality and bacterial risk, and found that eggs stored at refrigeration temperature maintained superior interior quality compared with those stored at room temperature. 

Moreover, research published on the National Library of Medicine claimed that when eggs are stored at higher temperatures or are subject to condensation (for example, when chilled eggs are moved to room temperature), the risk of bacteria such as Salmonella enterica penetrating the shell or multiplying inside is increased. 

For example, one study found that mice fed eggs stored at 25 degrees C developed salmonellosis, whereas those fed eggs stored at 5 degrees C did not. 

That said, there are regions (many European countries) where eggs are not washed and the cuticle remains intact, hens may be vaccinated against Salmonella, and ambient storage at room temperature is standard.

In such systems, the natural protection means refrigeration is less critical. But the key takeaway for a typical consumer: if your eggs have been washed, refrigerated and transported cold, they should remain in the fridge. Once eggs are refrigerated, they should not be left out at room temperature long-term. 

In summary: To minimise risk and preserve freshness, refrigerating eggs is the safer choice - especially in systems where the natural shell protection has been removed or compromised.