We’ve all been there staring at a carton of eggs in the refrigerator, trying to remember when we bought them. Are they still good? Should you use them in your breakfast or baking project? Eggs can remain safe to eat for surprisingly long periods, but their quality does decline over time. Knowing how to determine an egg’s freshness isn’t just about avoiding unpleasant tastes or smells it’s about food safety. These simple tests can save you from the unfortunate experience of cracking a rotten egg into your cake batter or breakfast skillet.
Contents
Table of Contents
Why Testing Egg Freshness Matters
- Food Safety – Consuming rotten eggs can lead to foodborne illness from bacteria like Salmonella
- Cooking Performance – Fresh eggs perform better in recipes, especially where texture and structure are important
- Waste Reduction – Knowing how to test eggs helps avoid throwing away perfectly good food
- Money Saving – Reduce unnecessary spending on new eggs when your current ones are still usable
Method 1: The Float Test (Water Glass Method)
The float test is perhaps the most reliable and easiest method to determine an egg’s freshness. This test works because as eggs age, the small air pocket inside them grows larger as moisture evaporates through the porous shell and air enters.
How to Perform the Float Test:
- Fill a bowl or tall glass with enough cold water to fully submerge an egg.
- Gently place the egg in the water.
- Observe the egg’s position in the water:
- Fresh eggs will sink and lay horizontally on their side at the bottom of the container
- Week-old eggs will still sink but stand upright, with the wider end pointing upward
- Older eggs (2-3 weeks old) will float partially, with part of the egg breaking the water’s surface
- Very old eggs will float completely on the water’s surface
Understanding the Results:
Eggs that sink are fresh and perfectly fine to eat. Eggs that stand upright are still good but should be used soon. Eggs that float are older—while not necessarily unsafe, they’re past their prime and should be subjected to additional tests before using.
Method 2: The Sniff Test
Your nose can be a powerful tool in determining if an egg has gone bad. Fresh eggs have either a neutral smell or no smell at all. A rotten egg produces hydrogen sulfide gas, which creates an unmistakable and unpleasant odor.
How to Perform the Sniff Test:
- Crack the egg into a small bowl (never directly into a recipe or pan).
- Put your nose close to the egg and inhale.
- If you detect any sulfurous or foul smell—trust your instincts and discard the egg immediately.
Additional Notes:
Perform this test in a separate bowl so you don’t contaminate other ingredients if the egg is bad. This is especially important when baking or preparing dishes with multiple eggs.
Method 3: The Visual Inspection
A fresh egg has certain visual characteristics that change as it ages. Examining an egg both before and after cracking can provide clues to its freshness.
Before Cracking:
- Hold the egg up to a light source (a process called “candling”).
- Fresh eggs appear more translucent with a small, barely visible air cell.
- As eggs age, they become more opaque, and you can see a larger air pocket inside.
- Check for any cracks, slime, or powdery substances on the shell—these are signs of potential contamination.
After Cracking:
- Crack the egg onto a flat white plate for better visibility.
- Fresh egg whites are thick, firm, and gather closely around the yolk.
- Fresh yolks stand tall and maintain a domed shape with a firm membrane.
- As eggs age:
- The whites become thinner and spread out more
- The yolk flattens and breaks easily
- You might notice pink, green, or black discoloration (discard immediately if present)
Method 4: The Shake Test
The shake test is quick and doesn’t require any tools, making it convenient when you’re in a hurry or don’t want to waste an egg by cracking it open.
How to Perform the Shake Test:
- Hold the egg next to your ear.
- Gently shake it, rotating slightly.
- Listen carefully:
- Fresh eggs make little to no sound when shaken
- Older eggs may produce a sloshing sound as the yolk and white have started to deteriorate and become more liquid
- A distinct sloshing indicates the egg is quite old
Why This Works:
As eggs age, the vitelliform membrane (which holds the yolk in place) weakens, allowing the yolk to move more freely within the egg. Additionally, the egg white (albumen) becomes thinner and more watery over time.
Method 5: The Julian Date Check
While not a physical test like the others, checking the Julian date on egg cartons can be very helpful in determining freshness. In the US, egg cartons are required to show the pack date.
How to Read Egg Carton Codes:
- Look for a three-digit number on the carton (the Julian date).
- This number represents the day of the year when the eggs were packed:
- January 1 = 001
- December 31 = 365 (or 366 in leap years)
- Eggs are generally good for 4-5 weeks from this date if refrigerated properly.
Some cartons might also have a “sell by” or “best by” date instead of or in addition to the Julian date. Remember that eggs can be good for 3-5 weeks from the purchase date if properly refrigerated.
Bonus Tips for Egg Storage and Freshness
- Temperature Matters – Store eggs in the coldest part of your refrigerator (not the door) at 40°F (4°C) or below.
- Original Carton – Keep eggs in their original carton, which protects them from absorbing odors and helps maintain humidity.
- Pointy End Down – Store eggs with the pointed end facing downward to keep the yolk centered and the air cell at the top.
- Don’t Wash Until Ready to Use – The natural coating on eggshells helps preserve freshness.
- Older Eggs Have Benefits – Slightly older eggs (7-10 days) are actually better for hard-boiling as they peel more easily.
When to Definitely Discard Eggs
While the tests above can help determine freshness, there are some situations when eggs should be thrown away without question:
- Eggs with cracked or damaged shells
- Eggs with a strong, sulfurous odor
- Eggs with discoloration in the white or yolk (green, pink, or black)
- Eggs that have been left at room temperature for more than 2 hours
- Any egg you’re uncertain about (when in doubt, throw it out)
Final Thoughts
Learning to determine egg freshness is a valuable kitchen skill that reduces food waste and ensures food safety. The float test and visual inspection are particularly reliable, while the other methods provide helpful secondary confirmation. By combining these techniques, you can confidently use eggs for everything from simple breakfasts to delicate baking projects, knowing they’re at the optimal freshness for your needs.
Remember that these tests primarily indicate freshness and quality rather than safety alone. Always use proper food handling practices, cook eggs thoroughly, and trust your instincts if something seems off no egg is worth risking foodborne illness.