Egg storage recommendations vary globally, leading to confusion about how long eggs can be safely kept at room temperature. This article explains the science behind egg storage and offers guidance for consumers.
Understanding Egg Storage Differences
Egg storage recommendations vary significantly across regions, primarily due to differences in egg processing methods. In the United States, commercially produced eggs are typically washed and sanitized to remove potential surface bacteria, including Salmonella. This washing process, however, also removes a natural protective layer on the eggshell called the cuticle.
The cuticle is a proteinaceous layer that seals the egg’s pores, serving as a physical and chemical barrier against microbial penetration. Once the cuticle is removed, the eggshell becomes more porous and vulnerable to bacterial entry. To counteract this, washed eggs in the U.S. are required by federal regulations to be refrigerated to prevent bacterial growth. In contrast, many European countries do not wash eggs commercially; instead, they often focus on vaccinating hens against Salmonella and rely on the egg’s natural cuticle. This difference means unwashed eggs with an intact cuticle can be safely stored at room temperature in those regions.
Guidelines for Room Temperature Storage
The feasibility of storing eggs at room temperature largely depends on whether they have been washed and if their protective cuticle remains intact. For eggs purchased in the United States, which have undergone commercial washing, they must be kept refrigerated. If these washed eggs are left out at room temperature, they should not remain unrefrigerated for more than two hours.
Unwashed eggs, often sourced directly from farms or found in countries where washing is not standard, retain their natural cuticle. This intact cuticle offers a barrier against bacteria and moisture loss, allowing these eggs to be stored at a stable room temperature for a longer duration. Unwashed eggs can typically be kept on a counter for about two weeks. While refrigeration extends their shelf life significantly, potentially up to three months, room temperature storage is viable for unwashed eggs if consumed within this shorter timeframe.
Health Concerns of Improper Storage
Improper egg storage, particularly at elevated temperatures, poses a risk of bacterial growth, most notably from Salmonella enteritidis. This bacterium can be present inside an egg even before it is laid or can contaminate the shell surface. When eggs are stored at temperatures above refrigeration levels, Salmonella can multiply rapidly. Research indicates that Salmonella growth occurs more readily at higher room temperatures.
Consuming eggs contaminated with Salmonella can lead to foodborne illness, characterized by symptoms such as diarrhea, fever, and stomach pains. While symptoms typically resolve within a few days, severe infections may require medical attention, particularly for vulnerable populations like infants, the elderly, or those with compromised immune systems. The growth of these bacteria does not typically alter the egg’s taste, smell, or appearance, underscoring the importance of proper storage to prevent illness.
How to Check Egg Freshness
Even with proper storage, assessing an egg’s freshness before use is helpful. A common method is the float test: place an egg in a bowl of water. Very fresh eggs sink to the bottom and lie flat.
As an egg ages, its porous shell allows moisture to escape and air to enter, enlarging the internal air cell. An older, but still usable, egg might sink but stand upright. If an egg floats completely, it indicates a large air cell and should be discarded.
Another practical check is the sniff test. Fresh eggs have little to no odor. If an egg emits a strong, sulfur-like, or rotten smell when cracked, it has spoiled and should not be eaten.
Visual inspection also provides clues. A fresh egg cracked onto a flat surface will have a firm, rounded yolk and a thick, slightly opaque white that does not spread excessively. An older egg may have a flatter yolk and a watery white that spreads thinly.