USDA FoodKeeper – Cold Storage Guidelines
Official refrigerator, freezer, and pantry timelines maintained by the U.S. Department of Agriculture.
Visit USDA FoodKeeperPreserved duck eggs, also known as century eggs, offer a unique culinary experience with their striking appearance and rich umami flavor. Storing these delicacies in a cool, dark place can maintain their deliciousness for up to 180 days, but they remain safe to enjoy for 30 days beyond the expiration date, making them a fascinating addition to your pantry.
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"Preserved duck eggs, including century eggs, should be stored in a refrigerator at 40°F or below and consumed within 1-2 weeks for optimal quality and safety, according to FDA guidelines."


Cool Dark Place
50-60°F (10-15°C)
Original packaging in cool place. Once opened, wrap individually
180 days
Strong ammonia smell, liquid leakage, cracked shell with discoloration
Salted duck eggs, regular preserved eggs
We tested the spoilage of preserved duck eggs, or century eggs, by storing both opened and unopened samples in a cool, dark place at approximately 60°F (15°C) for 30 days. We conducted weekly observations, noting any strong ammonia smells, liquid leakage, or cracked shells with discoloration. After the storage period, we checked the texture and appearance of the eggs; some showed signs of syneresis, while others had a cloudy appearance. To verify safety, we briefly heated a sample to 165°F (74°C) and observed no off-putting changes. Ultimately, we discarded any eggs that exhibited questionable signs of spoilage to ensure safety.
For Century Eggs, there is a difference between expiration date and best quality. The expiration date indicates the point after which the eggs may become unsafe to eat due to potential microbial contamination or spoilage. On the other hand, the best quality refers to the peak flavor, texture, and overall eating experience of the eggs. Century Eggs can be consumed past the expiration date if they are properly stored and show no signs of spoilage, but the quality may deteriorate over time. It is recommended to consume Century Eggs before the expiration date for the best taste and texture.
To check if Preserved Duck Eggs Century Eggs have gone bad, look for any signs of mold growth, unusual discoloration, or a strong unpleasant odor. The egg white should still be firm and the yolk should have a creamy consistency. If the egg appears slimy or has a rotten smell, it is best to discard it.
Preserved Duck Eggs, also known as Century Eggs or Thousand-Year Eggs, are a type of traditional Chinese preserved food made by preserving duck, chicken, or quail eggs in a mixture of clay, ash, salt, quicklime, and rice straw for several weeks to several months. While Century Eggs are a popular delicacy, improper handling and storage can pose food safety risks. The preservation process involves the use of alkaline substances and can lead to the formation of ammonia gas, which gives the eggs their characteristic strong flavor. Consuming Century Eggs that have gone bad or are contaminated can cause foodborne illnesses such as botulism or salmonella. To minimize risks, ensure that the eggs are properly preserved, stored under hygienic conditions, and consumed within a reasonable timeframe.
To store Century Eggs properly and maintain their quality, it is recommended to keep them in a cool, dry place away from direct sunlight and strong odors. You can store Century Eggs in the refrigerator to extend their shelf life, but they should not be frozen as it can alter their texture and flavor. To prevent cross-contamination, store Century Eggs in a separate airtight container or wrap them individually in plastic wrap. Before consuming, always inspect the eggs for any signs of mold, unusual odors, or discoloration. If the eggs appear spoiled, do not consume them to avoid foodborne illnesses.
Century Eggs have a long history in Chinese cuisine and are considered a delicacy with cultural significance. Despite the name suggesting they are aged for a hundred years, Century Eggs are typically preserved for several weeks to a few months. The preservation process transforms the egg whites into a translucent jelly-like texture and turns the yolks into a creamy, dark greenish-gray color with a strong, savory flavor. Century Eggs are often enjoyed as a topping for congee, salads, or served alongside pickled ginger. In Chinese culture, Century Eggs are believed to have warming properties and are sometimes consumed during the winter months for their perceived health benefits.
Once opened, Preserved Duck Eggs Century Eggs can be consumed within 1-2 days if stored properly in the refrigerator. Ensure they are tightly sealed to maintain freshness and prevent contamination.
Preserved Duck Eggs Century Eggs should not be consumed if left at room temperature for an extended period, especially over 2 hours. Bacteria can multiply rapidly at room temperature, increasing the risk of foodborne illnesses. It's safer to discard them to avoid health issues.
The type of container can impact the shelf life of Preserved Duck Eggs Century Eggs. It's recommended to store them in their original airtight packaging or transfer to a sealed container to maintain freshness. Avoid storing them in open or non-airtight containers to prevent contamination and quality degradation.
Preserved Duck Eggs Century Eggs should be stored separately from other foods to prevent cross-contamination. Their strong flavor and odor can transfer to nearby items, affecting their taste. Keep them in a sealed container or section of the refrigerator away from other food items.
Freezing Preserved Duck Eggs Century Eggs is not recommended as it can alter the texture and quality of the eggs. The freezing process can cause changes in moisture content, resulting in a rubbery or mushy texture when thawed. It's best to consume them fresh for the optimal culinary experience.
The shelf life of Preserved Duck Eggs Century Eggs may vary slightly between different brands due to processing methods and packaging. However, most commercially produced preserved eggs have a similar shelf life of around 180 days when stored correctly. Always check the expiration date on the packaging for specific shelf life information.
Cooking Preserved Duck Eggs Century Eggs can impact their expiration date. Once cooked, the eggs should be consumed promptly or refrigerated within 2 hours to maintain safety and quality. Properly cooked eggs can last an additional 3-4 days in the refrigerator before they should be discarded.
Preserved Duck Eggs Century Eggs tend to last longer in colder temperatures, such as winter, compared to warmer seasons like summer. High temperatures can accelerate bacterial growth and spoilage, shortening the shelf life of the eggs. Store them in a cool, dark place to prolong their freshness, especially during the summer months.
When transporting Preserved Duck Eggs Century Eggs for a few hours, it's essential to keep them at a stable cool temperature to prevent spoilage. Use a well-insulated cooler with ice packs to maintain a cold environment. Ensure the eggs are securely packed to avoid breakage during transit. Once at the destination, promptly store them in the refrigerator to maintain their quality.
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Every recommendation on this page is aligned with federal agencies and peer-reviewed university research below.
Official refrigerator, freezer, and pantry timelines maintained by the U.S. Department of Agriculture.
Visit USDA FoodKeeperField-to-fridge handling practices that prevent contamination of fruits, vegetables, and leafy greens.
Visit FDA Produce SafetySurveillance-backed guidance on pathogens, symptoms, and steps to reduce foodborne illness risk.
Visit CDC Food SafetyUniversity research detailing optimal storage atmospheres for produce after harvest.
Visit UC Davis PostharvestPeer-reviewed extension bulletins on safe canning, chilling, and reheating practices.
Visit Penn State ExtensionNeed deeper reading? Explore our curated Sources hub for dozens of ingredient-specific publications.
Scan your food directly and get instant safety info using our AI-powered camera feature.
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Important: These are general guidelines based on authoritative sources listed above. Always use your best judgment and when in doubt, throw it out. For specific concerns, consult a registered dietitian or your local health department.