I sell the occasional carton of eggs, and a frequent question I receive regarding my eggs is about refrigeration. Should you refrigerate farm eggs? I’m going to address that for you today.
Here’s the Short Answer:
This post will go into some detail, with references included, but for those who want the short answer here it is: clean, fresh farm eggs that have not been washed or previously refrigerated can be stored on the counter safely no more than one to two weeks for maximum freshness and flavor with minimal bacterial contamination. For longer shelf life, store them in the fridge for up to five weeks, and often longer. If you do not have access to a refrigerator, at least one study has proven that eggs can be kept for three to four weeks at room temperature if they have been coated in vegetable oil2.
Here’s the Long Answer:
Right before an egg passes out of a bird’s (any bird’s) body, a protective layer, scientifically known as the cuticle, is deposited on the egg5, 10. Colloquially, most folks refer to this protective layer as the bloom. Eggs are porous to allow oxygen to be received by a developing chick, but these pores also leave the egg vulnerable to bacterial contamination. Bacteria is one of the primary reasons eggs will spoil so to avoid contamination, the bloom fills the pores to prevent bacteria crossover10. This means that while an intact bloom is present, the egg is shelf stable.
In the case of eggs purchased from your average grocery market in the US, the eggs were washed immediately after laying, thereby removing the bloom, and promptly refrigerated1. Any time the bloom is removed the eggs are made vulnerable to bacteria penetration10. Even if the bloom is left intact, once the egg is refrigerated it must remain refrigerated. This is because when an egg is cold and placed in a warmer environment it will sweat, and the resulting moisture disrupts the bloom.
There is nothing wrong with washing and refrigerating eggs. In fact, salmonella is the leading cause of foodborne illnesses world wide, with eggs identified as the source in roughly 53% of cases in the US as reported by the CDC4. That is to say, it is incredibly important to take egg storage seriously.
With farm eggs, a properly maintained coop with clean nesting boxes means that most eggs are laid with a beautiful clean shell and a fully intact bloom. Provided the eggs are collected soon after laying and they didn’t reach cold temperatures (for example, if they were laid on a cold winter day and left in the brood box to cool down), the eggs can be safely kept at room temperature for a short period of time. I’ve been hard pressed to find exactly how long it is safe to keep eggs at room temperature, but one frequently cited article from 1970 states that the bloom starts to break down after four days8. One article from Mother Earth News equates one day on the counter to seven days in the fridge, and other blog posts suggest anywhere from 1 to 4 weeks on the counter is safe for unwashed eggs2, 6, 7. But what is actually safe?
I wanted to dig a little deeper into egg preservation methods, and I did come across a few studies, of which I had free online access. In one study, by Eke, M. O. and colleagues in 2017, researchers wanted to assess egg storage techniques for developing countries, such as Nigeria, in which a refrigerator may not be available. They looked at three methods for storage: unwashed, stored at room temperature; unwashed eggs coated in vegetable oil stored at room temperature; and eggs that have been refrigerated. They assessed several parameters of egg quality, including bacterial, mold, and yeast contamination; loss of weight, change in Ph, and overall yolk and albumin quality. In all parameters measured, by Week 1 the non-refrigerated and non-oiled eggs were already decreased in all measures, while the oiled eggs and refrigerated eggs were still pretty close in quality to each other, and have changed little from the Day 1 measures. By weeks two, three, and four the room temperature and non-oiled eggs were radically decreasing in quality, while the other two groups were still close to each other. In the bigger picture, the refrigerated eggs retained the highest quality, but the oiled eggs were a close second, while the non-refrigerated and non-oiled eggs quickly decrease in quality.
When choosing to store eggs at room temperature, it may be wise to coat your eggs in vegetable oil!
How I Handle My Eggs
Earlier I mentioned clean eggs with a fully intact bloom. Unfortunately chickens are not perfect creatures, and even the cleanest coop cannot stop a chicken who has stepped in poop from stepping on her egg, or on an egg that’s already been laid. Sometimes poop happens! Anytime I have a small amount on my egg, I wipe it off and cook it within 1-2 days. If I don’t plan on cooking with it I put it straight in the fridge. Even an intact bloom is not a perfect barrier against poop sitting directly on an egg. Salmonella is no joke! (See FDA article if you don’t believe me!)
If the egg is heavily coated with poop, I absolutely never give it to a customer. I select only the cleanest eggs for distribution and store them in the refrigerator for maximum shelf life. For myself, I wipe it off and bake it in a baked good to ensure it is well done. I do not fry or those eggs, just in case. Fortunately, it’s rare I have a really dirty egg, and I bake a lot.
If you are really worried about egg safety, the only tried and true method of avoiding foodborne illness from eggs is to use fresh eggs, and cook them well done. But who am I kidding? I’ll take mine sunny side up.
1“Cleaning.” Incredible Egg, http://www.incredibleegg.org/eggcyclopedia/c/cleaning/.
2“Day 13 – Must Fresh Eggs Be Refrigerated?” Living Homegrown, 23 Oct. 2014, livinghomegrown.com/day-13-must-fresh-eggs-be-refrigerated/.
3Eke, M.O., et al. “Effect of Storage Conditions on the Quality Attributes of Shell (Table) Eggs.” Nigerian Food Journal, No Longer Published by Elsevier, 10 May 2015, http://www.sciencedirect.com/science/article/pii/S0189724115300722.
4Food and Drug Administration, HHS. “Prevention of Salmonella Enteritidis in Shell Eggs during Production, Storage, and Transportation. Final Rule.” Federal Register, U.S. National Library of Medicine, 9 July 2009, http://www.ncbi.nlm.nih.gov/pubmed/19588581/.
5Gole, Vaibhav C, et al. “Effect of Egg Washing and Correlation between Eggshell Characteristics and Egg Penetration by Various Salmonella Typhimurium Strains.” PloS One, Public Library of Science, 12 Mar. 2014, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3951326/.
6Happy Chicken Coop. “The Happy Chicken Coop.” The Happy Chicken Coop, 13 Jan. 2020, http://www.thehappychickencoop.com/how-to-store-your-chickens-freshly-laid-eggs/.
7Steele, Lisa. “Should I Refrigerate My Farm-Fresh Eggs?” Mother Earth News, 2016, http://www.motherearthnews.com/real-food/should-i-refigerate-farm-fresh-eggs-zm0z16aszsor.
8Vadehra, D. V., et al. “Role of Cuticle in Spoilage of Chicken Eggs.” Wiley Online Library, Journal of Food Science, Jan. 1970, onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2621.1970.tb12354.x.. “Role of Cuticle in Spoilage of Chicken Eggs.” Wiley Online Library, Journal of Food Science, Jan. 1970, onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2621.1970.tb12354.x.
9Whiley, Harriet, and Kirstin Ross. “Salmonella and Eggs: from Production to Plate.” International Journal of Environmental Research and Public Health, MDPI, 26 Feb. 2015, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4377917/.
10Wilson, Peter W, et al. “Understanding Avian Egg Cuticle Formation in the Oviduct: a Study of Its Origin and Deposition.” Biology of Reproduction, Oxford University Press, 1 July 2017, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5803769/.