How Do You Know if an Onion Has Gone Bad? - The Kitchen Journal (2023)

Just like salt and pepper, onions are a staple when it comes to cooking. Without them, your dish would be incomplete. Onions are essential for flavor while holding numerous health and nutritional benefits.

Usually, onions are available loosely or pre-packed into bulk quantities. I typically try to buy just what I need. But what happens if the recipe calls for only half an onion? What if you have purchased one too many onions? How do you store them and keep them from fresh? How do you know if an onion has gone bad?

Here’s where I come in. I’ve researched everything there is to know about onions, so you do not need to. For example, the tell-tale signs of onions going bad and the different environments you can store onions, and how long they will last. Keep reading to learn how to know if an onion has gone bad, as well as tips to prolong the freshness of your onions.


How Do You Know if an Onion Has Gone Bad?

How Do You Know if an Onion Has Gone Bad? - The Kitchen Journal (1)

Onions, like all other fresh produce, are perishable. Onions are usually delivered fresh to the supermarket and have no definite best before date. So, you’ll have to keep track of the onions by the date of purchase.

Generally, you can expect your onions to last and remain fresh for a few months. However, it truly depends on the condition they are in and how you store them.

You’ll be able to tell if an onion has gone bad by the three basic tell-tale signs: color, touch, and smells. The tell-tale signs of a spoiled onion also depend on whether they are whole, chopped, or sliced.

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How Do You Know if a Whole Onion Has Gone Bad?

If your whole onion is soft and mushy, that is a definite sign that it is spoilt. A fresh onion should be firm and smooth. Black or brown spots on an onion are another sign of it going bad. These spots will eventually form mold on the surface of the onion.

With that being said, you don’t necessarily have to throw them away. Salvage the good parts of the onion by carefully cutting off the mushy and black spots.

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How Do You Know if a Chopped Onion Has Gone Bad?

Chopped and sliced onions should be refrigerated to maintain their freshness. However, that doesn’t mean they will last forever edible in the fridge. If the chopped onions are slimy and smell like anything other than an onion, they should be tossed in the bin.

What Does White Liquid from Onion Mean?

Firstly, white or clear liquid in any onion is perfectly normal. It doesn’t mean the onion has gone bad and you do not need to bin it.

So why is there liquid oozing out when you are cutting an onion? Well, onions are porous and can hold water and nutrients rather well. Once you cut into an onion, it will release the onion cells’ water and nutritional content. In short, you can call it raw onion juice. Usually, fresh onions are juicy and contain a lot of water content. Older onions will dry out and turn leathery.

Also, wondering why onions irritate your eyes and make you cry? It’s induced by a gas chemical found in the raw onion juice called propanethial S-oxide. This gas irritates your eyes and causes you to tear.

Black Mold on Surface of Onion

Black mold on onions is a common problem. It’s caused by a fungus found in soil called aspergillus niger. It usually starts at the top of the bulb and makes its way to the bottom.

Why is there Black Mold?

Mold is a pesky and unavoidable matter. Here are a few reasons why your onion maybe moldy:

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  • Bruised onions from dropping them or bumping into other onions – the bruised areas are a pathway for fungus to enter and cause it to be moldy
  • Unsanitary conditions or bacteria from nearby moldy vegetables
  • Poor air circulation and high humidity allow the fungus to prosper and grow

Does Black Mold Mean the Onion Has Gone Bad?

You will be glad to know that you do not need to immediately toss away a moldy onion. As long as the onion has not been severely affected by mold or is soft and mushy, it is good to eat.

You can peel off the moldy layer of the onion or cut off the moldy parts. Wash the onion and consume it as soon as possible.

Inhaling or ingesting aspergillus niger rarely causes food allergies. However, you are advised not to eat the onion if you are allergic to aspergillus.

What Happens if You Eat Bad Onions?

How Do You Know if an Onion Has Gone Bad? - The Kitchen Journal (2)

Breathe. Eating a gone off onion will not kill you. Onions and shallots are some of the safest vegetables. Most people walk away with no symptoms or with a slightly upset stomach.In most cases the worst thing to happen when an onion has gone bad is that the taste is unpleasant. Granted, ruining the flavor of your dish isn’t a small issue!

In most instances, food reactions are not because of a lousy onion but because of other factors. Factors such as having an allergy or not washing your onions properly, or cross-contamination in the kitchen. So, it’s important to remember to keep your kitchen surfaces clean.

How Long Do Onions Last in the Fridge?

Storing onions in the fridge is usually not advised, as you have learned onions should be stored in a dry and well-ventilated place. If not, onions will get mushy and rot.

However, storing onions in the fridge could extend their shelf life, mainly if they have been chopped or cooked.

Whole raw onions can be kept in the fridge for two to three months. Peeled raw onions can last up to 10-14 days refrigerated. Fresh chopped or sliced onions can be refrigerated for as long as 10 days when stored properly. You should wrap the onions in plastic or store them in a clean airtight container. This will prevent cross-contamination as well as stop you from stinking up your fridge with onion.

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Raw onions would still be safe to eat after this period. However, the texture may become slightly soft and mushy due to the moisture. You may also notice that they lose some of their characteristic taste.

On the other hand, cooked onions should be eaten as soon as possible. They can only last up to three to five days refrigerated. Store them in the fridge inside an airtight container.

How Long Do Onions Last in the Freezer?

Freezing raw onions will give them a maximum shelf life of up to eight months. Chopped or sliced onions can be frozen for three to six months. You can also freeze cooked onions and store them in the freezer for up to 12 months.

How Long Do Onions Last in the Cupboard?

If you are like me and store your onions in the kitchen cupboard, you can expect your onions to last for two to three months. With that being said, the onions should be appropriately stored in a cool, around 45–55-degree F, dark and well-ventilated area.

The onions could last longer than this period. It would be best to periodically check on them every now and then to ensure no mold is growing.

How Long Do Onions Last at Room Temperature?

How Do You Know if an Onion Has Gone Bad? - The Kitchen Journal (3)

If you cannot find a well-ventilated or cool area to store your whole raw onions, they can last up to a week at room temperature. Of course, this varies to every situation and whether they have been stored properly. After a week, regularly check for any mold and if your onions have gone bad.

How to Properly Store Onions

Storing Whole Raw Onions

  • Find a cool, dark, and well-ventilated area to store your onions. Such as the basement, in your kitchen cabinet, or your pantry
  • Remove onions from the plastic bag, if any – plastic bags will cause your onions to go bad quickly due to poor ventilation
  • Keep onions in a mesh bag, paper bag with punched holes, or a container without the lid on – to ensure ample air circulation
  • Try not to store onions next to potatoes – Onions release ethylene gas, which will cause the potatoes to sprout. The moisture from both vegetables will also cause them to spoil faster.

Storing Chopped and Cooked Onions

Once peeled, chopped or diced, or cooked, store them in a clean airtight container or plastic bag in the refrigerator. Cooked onions should be consumed as soon as possible.

How to Freeze Onions

Freezing onions is easy and a great way to extend their shelf life.

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Freezing whole onions is generally not advised as this would lead to a mushy mess when thawed. However, freezing them in chunks is perfect. Here is how you can freeze onions:

  1. Peel and chop or dice your onions in whatever shape you like.
  2. Spread the chopped onions on a tray and freeze for a few hours. (This step is crucial to not resulting in a clump of onion cubes stuck together)
  3. Quickly remove the tray from the freezer and divide the onions into clean bags or airtight containers.
  4. Label the bags and store them in the freezer. They will be good to freeze for up to 12 months if stored properly.

Be warned, frozen onions will be mushy and not as crisp as fresh onions, but the taste of frozen onions are as good as fresh onions. Frozen onions are best for soups, stews, and almost every dish. No thawing is needed, just toss them in, and you can get cooking.

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How can you tell if an onion has gone bad? ›

Spoiled onions may develop dark spots, which will eventually begin to grow mold. You'll also want to avoid onions that have started sprouting, as this indicates they're beginning to go bad. You can also feel your onions to check how fresh they are. Onions with soft or mushy spots are starting to go bad.

How long does onion go bad? ›

How long do onions last? According to The Chef's Garden cookbook, onions stored at temperatures between 30°F and 50°F will keep for up to one year. Otherwise, they'll last for several weeks. Store cut onions in the refrigerator (or even the freezer)…

How do you know if an onion is bad Reddit? ›

Normally they're softer than they should be and the stem/stalk end is soft, mushy, or damp in some way.

Is a watery onion bad? ›

Any onion that has damp or limp outer layers or a soft and squishy body should be discarded. Other signs can also include spots or discolouration, and a powdery silver-green mould. Ideally, store your onions in an open basket, in a dark, cool and dry place, or freeze them for even longer storage.

What does a rotten onion look like? ›

Soft Spots - the easiest way to spot a bad onion is if it has mushy spots, brown spots, black spots, or a slimy texture. These may look like indentations or they may just be discolorations. Sprouting - sprouting may be visible before or after cutting into the onion.

Is an onion bad if it starts sprouting? ›

Yes, you can; there's nothing toxic or dangerous about using a sprouted onion. However, sprouting may result in a softer onion with a more bitter taste, which some people find less desirable (especially when eaten raw).

Do dry onions go bad? ›

Shelf-Life: Dehydrated Onions will store for 10 to 15 years in a sealed #10 can (oxygen absorber included) under ideal storage conditions (cool, dry place). Once opened, it has an average shelf life of 6 to 12 months.

How can you tell if green onions are bad? ›

You know the green onion has gone bad when it's slimy. Avoid buying green onion with floppy leaves. If your green onion has floppy or wilted outer leaves, discard them before using the good parts.

Why does my onion look milky? ›

What we think of as “layers” of an onion are actually leaves whose primary purpose is storage. So, slice an onion and you're slicing open cells and releasing the water, sugars and other substances they'd been storing. Sometimes you can actually see the cells' juices as a milky white liquid.

Can you still eat an onion that has mold? ›

Rinse off small amounts of the black mold on the outer scales of the onion under cool, running tap water or cut off the affected layers. The unaffected part can be used.

What color onions are recalled? ›

Whole raw red, white, and yellow onions imported from the State of Chihuahua, Mexico
  • Multiple companies recalled onions. ...
  • See recall notice for information about each company's recall.
Feb 2, 2022

Why is the inside of my onion brown and mushy? ›

This problem is caused by a fungus or bacterium entering the onion bulb through the neck of the plant. Generally only one layer of onion is affected making it impossible to diagnose until the onion is cut open. The infection most often occurs just before or right at harvest time.

Can you eat brown onion raw? ›

Organic sulfur compounds help reduce the level of cholesterol in your body and may also help break down blood clots, lowering your risk for heart disease and stroke. You should eat onions raw rather than cooked to get the most sulfur compounds from them.

Do onions like to be wet? ›

Onions are shallow-rooted and require constant moisture for good growth. If the planting does not receive one inch of rain each week, soak the soil thoroughly at least once a week.

What does a moldy onion look like? ›

What you see: Powdery black lines, clusters, dots or smudges on your onion. You may see black sooty stuff on the paper-like exterior and/or the inner layers. What it is: Mold! Eat or toss: Do not eat moldy areas or use them for stock; discard them.

Is my onion dirty or moldy? ›

It looks like mold but also seems a little like dirt or soot. A: That black, sooty-looking substance on the skins of onions is indeed a mold, specifically, Aspergillus niger. It is common on onions, both in the field and once dried, bagged and stored.

What does onion white rot look like? ›

White, fluffy fungal growth appears on the base of the bulb, and later this growth becomes covered in small, round, black, seed-like structures called sclerotia.

What is the green thing growing out of my onion? ›

If you notice a green sprout emerging from the top of an onion, it means it's trying to regrow. By separating the sprouts inside an onion's layers and planting them in good soil you can grow multiple new onions within a single season.

Do onions go bad in the heat? ›

Although we do not think much about it, a little temperature difference is all it takes for onions to go bad. The ideal temperature range for storing them is 40-50OF. Too hot and the onions start sprouting and drying or too cold and they lose their hardness, discolor and become moldy.

Are soft onions OK to eat? ›

Signs Your Onion Has Spoiled

If your onion has gone bad, it will be pretty obvious. Squishy onions should be tossed into the trash without a second's thought. The same can be said for stinky onions or onions that have excess moisture. The less obvious signs are small wet spots, brown spots, or a softened texture.

Should onions be hung to dry? ›

After harvesting, dry or cure the onions in a warm, dry, well-ventilated location, such as a shed or garage. Spread out the onions in a single layer on a clean, dry surface. Cure the onions for two to three weeks until the onion tops and necks are thoroughly dry and the outer bulb scales begin to rustle.

Why do onions turn clear? ›

Those occasional see-through layers: Get rid of them? Those are called translucent scale , and they occur as the onion undergoes extreme temperature changes during growing or storage. They are edible.

Why do onions turn GREY? ›

What happened? Red onions—as well as other red produce, including cabbage and cherries—are rich in pigments called anthocyanins. When they're cooked with acid, their color intensifies, but when combined with an alkaline component, they can turn a startling bluish-green color.

Why are my onion sets rotting? ›

Onion neck rot is a disease of onions and shallots caused by the fungus Botrytis allii. Plants infected by the fungus usually appear perfectly healthy whilst the crop is growing. Symptoms are not usually seen on the bulbs until they have been in store for several weeks.

How long does it take for an onion to grow mold? ›

Comments on the Disease

Black mold occurs most commonly where onions or garlic are grown under warm conditions, such as the desert areas of California. Moisture must be present on the bulb for 6 to 12 hours for the disease to develop.

Do onions rot in the fridge? ›

Whole onions – it is not at all recommended to store whole onions in the refrigerator. This is because the air inside the fridge is very moist, causing them to rot quicker. Instead, they should be stored in a dark and cool dry place to make them last the longest, such as a pantry (see above).

What are the black spots inside onions? ›

Onion black mold most commonly occurs post-harvest, affecting bulbs in storage. It can also occur in the field, usually when bulbs are at or near maturity. The fungus enters the onion through wounds, either at the top, on the bulb, or in the roots, or it enters through the drying neck.

What brand of onions are on the recall list? ›

Recalled onions include the number 4159 and the Little Bear brand on the PLU sticker, like the one seen below. The onions were sold in bulk at stores in Florida, Georgia, Massachusetts, New York and Pennsylvania from June 22 to June 24.

What brands of onions have salmonella? ›

► Some red, yellow and white raw onions from ProSource Produce distributed in mesh sacks and cartons of various sizes under a variety of brand names, including Big Bull, Peak Fresh Produce, Sierra Madre, Markon First Crop, Markon Essentials, Rio Blue, ProSource, Rio Valley and Sysco Imperial.

Can you cut off bad part of onion? ›

As long as it does not have that intense rotting smell, you can safely remove the affected layers and continue to use the parts of the onion that are white.

Do unpeeled onions go bad? ›

Do unpeeled onions go bad in the fridge? For maximum freshness, onions should be peeled before refrigeration. If stored whole and unpeeled in the fridge, they will spoil within 7-10 days due to moisture absorption which can cause them to become mushy.

Do unpeeled onions go bad in the fridge? ›

Peeled onions can be stored in the fridge for up to two weeks, while diced or sliced onions will only last for 7–10 days (4). Avoid storing whole, unpeeled onions in the fridge, as they easily absorb moisture. Doing so may cause them to become mushy and spoil faster.

What does it mean when an onion is milky? ›

A milky onion is just a fresh onion releasing moisture when cut. Some onions are juicer than others so they release a milky looking liquid when you chop them.


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