1. The Float Test (Most Popular)
How to do it:
- Fill a bowl or glass with cold water.
- Gently place the egg in the water.
Results:
- Fresh egg: Sinks and lies flat on the bottom.
- Slightly older (still good): Stands upright on the bottom.
- Rotten: Floats to the surface.
Why it works:
As an egg ages, air seeps through the shell, forming an air pocket. The bigger the pocket, the more it floats.
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2. The Smell Test
How to do it:
- Crack the egg into a bowl and sniff.
Results:
- Fresh egg: Has no odor or a mild, neutral smell.
- Rotten egg: Has a strong sulfur or “rotten” smell — unmistakable and foul.
Tip: If it smells bad before cracking, discard it immediately.
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3. The Visual Inspection
How to do it:
- Examine the shell before cracking.
Results:
- Fresh: Shell is clean, smooth, and not slimy.
- Rotten: Cracked, slimy, or powdery shells (which can mean bacteria or mold).
Inside:
After cracking, the white should be thick and the yolk round and well-centered. A watery white or flattened yolk indicates age.
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4. The Shake Test
How to do it:
- Hold the egg up to your ear and gently shake it.
Results:
- Fresh: You won’t hear or feel much movement inside.
- Old or rotten: You’ll hear sloshing sounds — a sign that the egg’s contents have thinned and loosened.
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5. The Candling Test (Used by Farmers)
How to do it:
- In a dark room, shine a bright flashlight behind the egg.
Results:
- Fresh egg: The yolk is firm, and the air cell is small.
- Old or bad egg: Large air cell, moving yolk, or dark spots inside.
This test helps you see what’s happening inside the shell without cracking it.
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Quick Summary
| Test | Fresh Egg | Rotten Egg |
| Float Test | Sinks | Floats |
| Smell Test | No odor | Sulfur smell |
| Visual | Smooth shell, firm yolk | Slimy shell, flat yolk |
| Shake | No sound | Sloshing |
| Candling | Small air cell | Large air cell, dark spots |