Mayonnaise is a creamy, emulsified condiment that can go bad if not stored properly. Being able to identify signs of spoilage in mayonnaise is important to prevent foodborne illness. This article covers how to tell if mayonnaise is bad, proper storage methods, shelf life, and potential health risks of consuming spoiled mayonnaise.
Signs of a Fresh Mayonnaise
When first opened, mayonnaise should exhibit these qualities:
- Appearance – Smooth, creamy texture. No separation of oil or liquid.
- Color – Plain mayonnaise has a light eggshell yellow color. Flavored varieties are pale versions of their flavoring.
- Smell – Fresh, neutral odor. No off smells.
- Taste – Characteristic rich, tangy flavor.
- Consistency – Thick, creamy texture that spreads easily. Not runny, slimy or sticky.
Mayonnaise in peak condition will look and taste appealing, without any signs of spoilage.
What Causes Mayonnaise to Go Bad?
There are a few main causes of mayonnaise spoilage:
- Microbial growth – Bacteria, yeasts and mold can grow over time, especially if introduced through double-dipping. Common bacterial culprits include Bacillus, Staphylococcus, Listeria, and Salmonella species.
- Chemical rancidity – Fats oxidize over time, producing unpleasant flavors and odors. Exposure to air and warmth accelerates oxidation.
- Physical separation – The emulsion can break down, causing oil separation. This gives a curdled texture.
- Temperature abuse – Heat greatly accelerates microbial and chemical spoilage reactions. Storing mayo unrefrigerated promotes spoilage.
Properly storing mayonnaise inhibits microbial growth and oxidation to maintain freshness and shelf life.
6 Signs That Your Mayo Is Bad
Mayonnaise is a versatile condiment that can go bad quickly if not stored properly. Knowing how to identify signs of spoiled mayonnaise is important to avoid foodborne illness.
How to Tell if Mayonnaise is Bad or Spoiled? Watch for these key signs that indicate mayonnaise has gone bad:
1. Off Odor
Fresh mayonnaise has an appealing neutral smell. As it starts to spoil, the odor becomes unpleasantly sour, rancid or vinegary. Severely spoiled mayo gives off an ammonia-like rotten smell.
Key Point: There is a distinct unpleasant sour, rancid or ammonia-like odor when mayonnaise has spoiled.
2. Change in Color
The natural pale yellow color of mayonnaise can darken or take on grey, green or blue-ish tints as it spoils. Unnatural colors indicate microbial growth.
Separated brownish or dark yellow liquid is also a red flag for spoiled mayonnaise.
Key Point: Color changes or unnatural hues mean mayonnaise has gone bad.
3. Oil Separation
Fresh mayonnaise has a creamy, homogenous texture. As it spoils, watery liquid pools out on the surface as oil separates.
The emulsion has broken down, making the texture curdled and uneven. Discard separated mayo.
Key Point: Pooling or cloudiness shows oil separation in spoiled mayonnaise.
The appearance of mold, either dry fuzz or greenish fuzzy spots, means mayonnaise has spoiled. Yeasts and molds can grow even when refrigerated.
Discard moldy mayonnaise. Mold can spread throughout foods invisibly.
Key Point: Any mold growth in mayonnaise signals it has gone bad.
5. Slimy Texture
As mayonnaise ages and bacteria grow, it can develop a slimy, ropy texture. Extra mucus-like drippings or globs mean it is harboring high microbial levels.
Key Point: A distinctly slimy, sticky texture indicates bacterial contamination and spoilage.
6. Yeasty Smell
A strong yeasty or beer-like smell means fermenting microbes have grown and spoiled the mayonnaise. This gives an unpleasant sour, acetous odor.
Key Point: A yeasty odor shows overgrowth of fermenting bacteria or yeast.
How To Store Mayo?
Like any perishable food, mayo requires proper storage methods to maximize its shelf life and prevent spoilage.
Unopened Mayonnaise Shelf Life
The shelf life for unopened mayonnaise stored continuously at 40°F or below is:
- Unrefrigerated: 2-3 months past best by date on jar
- Refrigerated: 3-4 months past sell by date
Therefore, as long as it has been kept refrigerated, unopened mayo can generally safely be used for several months beyond the “Best By” or “Sell By” date on the jar.
However, it will begin deteriorating in quality after that date, so use within 3-4 months for best flavor and texture. Always inspect the contents before using expired mayonnaise.
Opened Mayonnaise Shelf Life
Once opened, the countdown begins to consume the contents quickly:
- Pantry: 2 months
- Refrigerator: 3-4 months
So mayonnaise lasts just 2-4 months once opened, even if refrigerated.
To maximize freshness, store opened mayo jars in the fridge and use within several weeks. Do not leave mayonnaise unrefrigerated once opened.
Refrigerate Mayonnaise Promptly
As with all perishable condiments, an opened or unsealed mayo jar or packet should be refrigerated promptly:
- Refrigerate within 2 hours of opening or purchase. Leaving mayo out too long at room temperature allows microbial growth and rapid spoilage.
- Maintain fridge temperature at 40°F or below. Avoid storing mayo on the door where the temperature fluctuates.
- Keep mayo towards the back of the top shelf to minimize temperature changes from opening the door.
Prompt refrigeration is key, as mayonnaise contains egg yolks and has a low pH, making it prone to spoiling when unrefrigerated for too long.
Store Mayonnaise in Airtight Container
After opening, transfer mayonnaise to an airtight container with a well-sealed lid to block oxygen exposure.
- Use a non-reactive storage container like glass or plastic. Avoid metal bowls which can react with egg yolks.
- Ensure lid fits tightly without gaps. Open lids allow fridge odors to seep in.
- Choose a container size that minimizes excess air at the top once filled. Too much air speeds spoilage.
- Make sure the container and lid are clean to avoid contaminating contents.
The right storage vessel protects both the flavor and safety of refrigerated mayonnaise.
Check for Expiration Date
Always verify expiration or “best by” date before purchasing and opening mayonnaise.
- Choose the jar or bottle with the furthest out expiration date when shopping.
- Take note of the date listed on the packaging to track fridge life after opening.
- Discard if contents are significantly past date on container. An expired date indicates possible spoilage.
While dates are not always exact, they provide good guidelines for peak quality. Use both dates and visual/aroma checks.
Can You Get Sick from Eating Spoiled Mayonnaise?
Yes, you risk foodborne illness and severe gastrointestinal symptoms if you eat mayonnaise that has gone bad. Potential dangers include:
- Salmonella – Can cause fever, diarrhea, abdominal cramps, and vomiting.
- Listeria – Can lead to headache, confusion, nausea, and diarrhea.
- E. coli – Causes severe diarrhea, dehydration, and abdominal pain.
- Staphylococcus aureus – Leads to intense vomiting and diarrhea.
Mayonnaise is a high-risk food since it doesn’t contain preservatives. Only consume mayo that hasn’t exceeded its shelf life and hasn’t been temperature abused. Discard if any odd changes in appearance, texture or smell develop.
Safe Handling Tips
Practice food safety when handling mayonnaise:
- Do not leave mayonnaise or any perishable spreads out for over 2 hours without refrigeration.
- Keep cooked and prepared foods like chicken salad with mayo refrigerated until serving time.
- Use clean utensils and containers to avoid cross contamination with bacteria.
- Discard any leftover spread or dip containing mayo after serving, do not save.
- Throw out recalled mayonnaise products immediately.
- Follow expiration or “use by” dates as a guideline for freshness.
Proper handling, storage and discarding at first signs of spoilage keep mayonnaise safe to enjoy.
Frequently Asked Questions
1. How can you tell if mayonnaise left unrefrigerated is still safe to use?
Mayonnaise left out more than 8 hours should not be consumed or tasted. At room temperature over 2 hours, bacteria multiply rapidly to unsafe levels that can still cause illness even if refrigerated again. Mayonnaise requires continuous refrigeration for safety.
2. What happens if you freeze mayonnaise after the expiration date?
Freezing cannot make spoiled mayonnaise safe to eat again. Mayonnaise should be frozen by the “Best By” date for proper texture and freshness, not after it expires. Mayonnaise kept frozen longer than 4-6 months will suffer more quality decline compared to fresh frozen. Discard if rancid odor, separation or discoloration is noticed after thawing.
3. Can you eat mayonnaise that smells a little odd or different?
No, it is unsafe to eat mayonnaise with any unpleasant or “off” odors, even if the texture appears normal. Unusual rancid or sour smells mean spoilage bacteria may have already grown to dangerous levels. Only consume mayonnaise that smells fresh. Discard any with odd smells.
4. Will microwaving or baking kill bacteria in bad mayonnaise?
It is not guaranteed. Some pathogens can survive heat from cooking, microwaving or baking. Consuming contaminated mayonnaise carries risks even after heating. Always discard mayonnaise that is moldy, oddly colored or smelly before considering using it in a recipe or dip.
5. How long can you keep mayonnaise after opening?
Once opened, mayonnaise should be discarded within 2-3 months even if refrigerated and no spoilage is visible. Its high protein content means quality and safety decline more rapidly after opening despite cold storage. Discard any mayo that shows signs of spoilage before the 2-3 month mark as well.
Check mayonnaise carefully for changes in appearance, texture and odor. Discard if any mold, slime, or rancid smell develops. Then replace with a fresh, quality product so you can continue enjoying creamy mayo without the risks of foodborne illness.