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Does 1000 year old egg expire?

Yes, 1000 year old eggs do expire and go bad eventually. However, due to their unique processing, they last much longer than regular eggs before going bad. With proper storage, 1000 year old eggs can last for several weeks or even months past the expiration date printed on the packaging.

What are 1000 year old eggs?

1000 year old eggs, also known as century eggs, pine patterned eggs, hundred year eggs, or millennium eggs, are a Chinese preserved egg product. Raw eggs are coated in a clay, ash, salt, quicklime, and rice hull mixture, then left to cure for several weeks or months. This curing process alters the egg whites and yolks, turning them into a dark brown, creamy, cheese-like texture with a pungent odor.

Despite their name, 1000 year old eggs do not actually last 1000 years. The name refers more to their appearance and altered texture than their actual shelf life. When cured properly though, they can last much longer than fresh eggs before spoiling due to their changed chemical properties.

How long do 1000 year old eggs last?

The shelf life of 1000 year old eggs depends on several factors:

  • Freshness when purchased – Fresher eggs will last longer
  • Curing process – Longer curing improves preservation
  • Storage temperature – Cooler temperatures prolong shelf life
  • Package integrity – Don’t use if packaging is damaged

Properly cured and stored 1000 year old eggs can last:

  • 1-2 months past the expiration date at room temperature
  • 2-3 months past the expiration date refrigerated
  • 4-6 months past the expiration date frozen

The expiration date printed on the packaging is a conservative estimate for best quality. Extending a few weeks or months past that is usually safe if the eggs have been kept cold and packaging is intact.

How to tell if 1000 year old eggs are bad

Signs that 1000 year old eggs have spoiled and should be discarded include:

  • Strong, offensive rotten odor
  • Watery texture or liquid oozing out
  • Mold growth on shell or packaging
  • Dark spots or slimy film on yolk or whites
  • foamy or bubbly appearance

If there is any doubt on the freshness, it is best to err on the side of caution and throw the eggs out. The altered chemistry of century eggs allows bacteria to grow faster once spoiled compared to regular eggs.

How to store 1000 year old eggs

To get the maximum shelf life out of 1000 year old eggs:

  • Refrigerate eggs at 40°F as soon as possible after purchase.
  • Store in original packaging, do not repackage into the egg tray.
  • Keep away from foods with strong odors that may absorb into the eggs.
  • Use oldest eggs first.
  • Do not freeze eggs in the shell, this will damage the egg whites.

Can you freeze 1000 year old eggs?

1000 year old eggs can be frozen to extend their shelf life, but proper preparation is important:

  • Do not freeze eggs in the shell, this will expand the contents and damage the egg whites.
  • Remove shells and membrane, rinse eggs in cool water.
  • Beat yolks and whites together or separate into different containers.
  • Pour into airtight freezer containers, leaving 1/2 inch headspace.
  • Label with contents and date.
  • Freeze for up to 6 months at 0°F.

To use frozen 1000 year old eggs, thaw overnight in the refrigerator before using. Use thawed eggs within 3-5 days.

Can you eat expired 1000 year old eggs?

It is not recommended to eat 1000 year old eggs much past their expiration date. While they may last weeks or months past the printed date if handled properly, eating spoiled eggs poses a real risk of food poisoning. Listeria, Salmonella, and other bacteria can grow rapidly in expired century eggs.

The altered pH and chemistry that gives 1000 year old eggs their unique flavor and texture also allows more pathogenic bacteria to thrive if the eggs do spoil. Consuming spoiled century eggs can cause symptoms like:

  • Nausea and vomiting
  • Abdominal cramps and diarrhea
  • Headache and fever
  • In severe cases, septicaemia and meningitis

If 1000 year old eggs have any signs of spoilage like odor, changes in color or texture, or mold, they should be discarded. The risk of getting sick from contaminated century eggs is not worth the chance just to avoid wasting some expired eggs.

How long do 1000 year old eggs last unrefrigerated?

Refrigeration is important for preserving 1000 year old eggs once cured. Without refrigeration, century eggs will spoil much faster:

Storage Temperature Shelf Life
Room temperature (68-72°F) 2-3 weeks after packaging date
Cool room (50-65°F) 4-6 weeks after packaging date
Refrigerated (40°F or below) 2-3 months after expiration date

The expiration date assumes refrigeration. At room temperature, 1000 year old eggs will go bad much faster, even if the packaging date hasn’t passed yet. For food safety, century eggs should always be kept refrigerated.

Can you eat 1000 year old eggs past the expiration date if the egg looks normal?

It is still risky to eat 1000 year old eggs past their expiration date even if they appear normal. Some harmful bacteria that cause food poisoning do not visibly alter the egg’s appearance. So century eggs can look fine but contain pathogens like Salmonella that can cause illness.

Also, the unique smell of 1000 year old eggs makes it harder to detect spoiled eggs by odor alone. Changes happening deep within the egg may not be obvious from the outside.

For these reasons, it is best to discard 1000 year old eggs by the expiration date printed on the packaging. The date accounts for the egg’s altered chemistry compared to regular eggs. Trying to extend the shelf life further, even if the eggs look normal, is not worth the risk of foodborne illness.

What happens if you eat a bad 1000 year old egg?

Eating a spoiled, rotten, or otherwise bad 1000 year old egg puts you at risk of food poisoning. The most common symptoms include:

  • Nausea, vomiting, diarrhea – Starts 12-72 hours after ingesting bad eggs.
  • Fever, headache, muscle aches – May accompany gastrointestinal symptoms.
  • Stomach cramps, abdominal pain – Caused by stomach and intestinal inflammation.

Symptoms are often self-limiting and go away after 1-3 days. However, severe cases can lead to dehydration or infection spreading into the bloodstream. At risk groups include pregnant women, younger children, older adults, and those with compromised immune systems. See a doctor right away if symptoms persist or fever develops above 101°F.

Preventing foodborne illness is the best reason to discard 1000 year old eggs by their expiration date. Following proper storage and food handling practices reduces the risks from eating century eggs.


1000 year old eggs can last 2-6 months past their printed expiration date if properly stored. However, century eggs do not actually last anywhere close to 1000 years. Signs like foul odors, sliminess, or mold signal the eggs have spoiled and should be discarded. Eating expired 1000 year old eggs poses a real risk of foodborne illness. While their unique processing methods allow century eggs to keep longer than regular eggs, they should still be refrigerated and consumed by the expiration date for food safety.