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How To Tell If Mayo Is Bad (Plus 6 Essential Storage Tips)

How To Tell If Mayo Is Bad (Plus 6 Essential Storage Tips)

With most foods, you have to see how to tell if mayo is bad, because we count on fresh-tasting mayonnaise that hasn’t spoiled or separated. 

Some people love mayo on everything. I’ve come to a point where I mostly eat simple sandwiches without it, but on a hearty sub with dense bread and lots of deli meat, it’s required. 

Picnic foods are often considered most at risk because lots of outdoor salads tend to contain mayonnaise: potato salad, macaroni salad, cole slaw, deviled eggs, etc. 

These potluck items will sit while waiting for people to serve themselves. So in a non-refrigerated state, it’s best to consume these within a couple of hours, and to use them up within just a couple of days. 

There is some debate about whether the acidity in mayo helps keep the germs at bay, and it’s the meat, onion, egg or whatever else in the dish that could be causing the illness or other issues.

That would mean that mayo may be helping to protect the rest of our dish with its own acidity. 

That said, we at CookingChew tend to stay on the safe side and recommend less time on the counter and more time in the refrigerator for most foods.

No, it isn’t okay to let mayo be left out overnight. 

As we know, mayonnaise is basically made from oil, egg yolk, vinegar, or lemon juice. These ingredients can go bad pretty quickly. 

Homemade mayo has a high risk of spoilage compared to those commercially made ones as the latter is loaded with preservatives that can kill harmful bacteria like salmonella. 

In addition, commercially made mayonnaise uses pasteurized eggs so the risk of having foodborne illnesses is reduced. 

In case you’re making your own mayo at home, it’s advised to consume the refrigerated food within four days ; the same day is even better.  

Also, keep in mind that consuming mayo that has been left out overnight at room temperature is NOT SAFE as bacteria grows incredibly fast in this storage condition. 

In fact, the USDA advises food that has been left out at temperatures ranging between 40 °F and 140 °F for more than two hours should be thrown away immediately. 

This seems to contradict what they say about mayo, but we like to maintain chilled foods. 

Remember, you deserve fresh, good food. Why risk it.

How to best store mayo

The shelf life of your mayonnaise depends on its freshness and storage condition. 

Typically, unopened and ready-made mayonnaise can last for up to four months in your pantry or about a year in the refrigerator. 

But you don’t need to refrigerate it unless you already opened the package or it’s not contaminated by other food or dirty utensils. 

This is because commercially made mayonnaise undergoes strict testing and contains ingredients and preservatives that can minimize bacterial growth.

Instead, keep it at a cold temperature and in a dry place away from sources of heat.

You can also check the “Best if Used By,” “Best Before”, or “Best When Used By” date on the mayo package to monitor its shelf life. 

For opened, commercially packaged mayonnaise, it’s advisable NOT to let it sit out at room temperature and store the creamy condiment in the fridge instead. 

Opened mayocan last for up to two months in the fridge if properly stored. 

Meanwhile, mayonnaise that’s being made at home should be kept inside the refrigerator and be consumed within seven days. 

Here’s how to store your homemade mayo in the fridge:

    1. Store in a container with a tight lid or an airtight container 
    2. Make sure it’s tightly sealed. 
    3. Place it in the fridge and consume it within a week.

Can you freeze mayo?

Though it’s unusual to freeze mayonnaise, yes, you can freeze the condiment to prolong its shelf life. BUT don’t expect to have a creamy texture after freezing the mayo. 

Just because you CAN doesn’t mean you SHOULD.

Generally, mayonnaise is an emulsion. So if you freeze it, there’s a big chance that the emulsion will break once the mayo is thawed, causing the ingredients to separate

The texture will not be the same once the eggs and oil separate and won’t serve as a creamy, spreadable condiment at that point.

How to tell if mayo is bad

The simplest and the most reliable way is to check the best-before date on the jar. However, relying on this doesn’t benefit you all the time. 

Sometimes opened jars of mayo have been left to sit out for hours or overnight repeatedly and then put back in the refrigerator, so you need to do a sniff test and look carefully.

The good news is there are a few signs that your mayo has gone rancid.

Molds and spores

If you happen to see spores in your mayonnaise or molds around the neck of the jar, it’s a clear sign that the product has gone bad and you should to throw it away immediately. 

And never EVER think about changing the container because this can’t save the mayo from spoilage. 

It’s safer to  throw it away!


Another way to tell if your mayo is already bad is to give it a sniff. 

Generally, bad mayonnaise gives off a slightly acidic smell or foul odor when you open the container. 

If your mayo is already in this state, avoid eating it.


The easiest way to determine whether your mayo has gone bad or not is by checking its appearance. 

Instead of having a white hue, spoiled mayonnaise typically has a yellowish or brownish color. 

You’ll also notice that the bad mayo doesn’t have a creamy consistency and there’s a presence of liquid on top. 

This separation may also indicate that a jar of mayo has been frozen and then thawed.


Relying on your sense of smell and sight to tell if your mayo is bad may notwork all the time. If that’s the case, you must do a taste test. 

Gently stir the mayo using a clean kitchen spoon and then give it a taste. If your mayo tastes sour or “off,” then it’s a red flag and you should throw it away!

Tips on storing mayo

Planning to extend the shelf life of your newly bought or made mayonnaise? These essential storage tips should get you started. 

After you obtain the product by creating your own or buying it in the grocery store, it’s suggested that you do these things so you can preserve its quality.

    1. Keep unopened and commercially made mayonnaise at a cold temperature and in a dry place away from sources of heat. 
    2. Check the “Best if Used By,” “Best Before”, or “Best When Used By” date in the mayo jar to monitor its shelf life. 
    3. Don’t let opened and commercially packaged mayo sit out at room temperature. 
    4. Once opened, store commercially made mayonnaise in the fridge.
    5. Homemade mayo should be kept inside the refrigerator and be consumed within seven days.

The bottom line

Processed mayonnaise that you bought from the store does use raw eggs in their recipes, but there are a lot of preservatives that allow a longer shelf life. 

Even opened mayo can last for a long time when kept cold in the refrigerator. 

But we find it’s best to not leave mayo out for hours on the counter, and especially not overnight.

We mentioned the debate above about whether or not mayo needs the precaution that we all think because so many ingredients (like meat and eggs) are not as acidic and could be the culprit for food poisoning. 

Mayo is mixed in with so many other things after all. 

Homemade mayo doesn’t have those preservatives and needs to be treated with far more care.

So we like to take care of our food the best we can and treat it with respect because it nourishes us (or makes us sick if we don’t.)

Be well, and I hope these tips help you figure out how to tell if mayo is bad.