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Four Ways How To Tell If An Onion Is Bad?

Onions are incredibly important to cooking. They are used in the cooking from all different cultures, and add key flavor to many dishes that would otherwise be bland.

There are many, many different varieties of onions, and each has its own unique characteristics. We most often see yellow, or cooking onions, red onions, and white, or Spanish onions in the grocery stores. 

Quick Answer: How To Tell If An Onion Is Bad?

On a scale from mild to strong in flavor personality, white are the most mild, yellow are a bit stronger, and red onions are the strongest. Closely related are leeks, shallots and green onions.

Onion types can be interchanged without catastrophic results. I know I have been caught needing a red onion and all I have are yellow, so I use what I have, and it’s fine.

If you are hosting company and making some special dishes, then you probably want to go to the special effort of making sure you have the recommended onions for the particular dishes.

There are also specific things like pickles that require a certain kind of onion, and in these cases, a different kind of onion should not be substituted.

With onions considered an essential cooking ingredient in so many recipes, it’s important to know how to purchase onions at peak condition, how to properly store them so they last for the maximum period of time, and when to toss those onions because they are bad.

How To Know When Onions Are Bad: Color?

First of all, you want to look closely at the onion for any discoloration.

Any spots of color that are different from the color of the onion you are using, i.e. yellow, white, or red, are signs that the onion is past its prime, and it would be better to forgo using it.

Specifically, we are talking about green, gray, brown or white spots on the onion. These spots are actually mold, and no one wants mold in their food. Mold can cause illness when digested, so it is best to discard the onion.

The Color Of The BulbWhen an onion is healthy, the bulb should be the color characteristic of that kind of onion, such as yellow, red, or white.
The outer layer should be a light brown or beige color.
MoldIf you remove the outer layer of the onion and notice any spots of discoloration on the flesh such as green, gray, brown, or white then this is a sign of mold. 
If there are any spots of discoloration, do not use the onion.

How To Know When Onions Are Bad: Sprouting?

Another visible sign that an onion is, in fact, going bad, is the presence of sprouting from the top of the onion.

You might think new growth is a good thing and indicates a healthy onion, but this is not the case. This is an indication that the onion is beyond its prime.

SproutingIf you see new growth sprouting from the top of the onion, this is a sign that the onion is past its best.
At the end of the onion’s growing season a flower will appear at the end of the stem. This means that the onion is finished growing and is going to seed.
You can still use the bulb, but if you have onions that you have bought or have dug up and stored and they are sprouting new growth, then this means that the onions are not at their best anymore.
Onions that have begun to sprout have usually become soft on the inside of the bulb.
An onion bulb that is soft is not unusable, however, it will not be at its best.
How To Know When Onions Are Bad: Sprouting?

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How To Know When An Onion Is Bad: Texture?

When an onion is not in its fresh, best state, it is softer on the inside.

If the onion has been sitting in your crisper drawer for some time and you forgot all about it, you may come across it when you’re hunting for something else, and discover a mushy blob.

Limp, Damp Outer LayerThe papery layer, called the tunic, that is  on the outside of the onion bulb is crisp and light-weight. It is easy to peel off.
When an onion is getting beyond its best, the tunic becomes limp and loses its crispness. It can also take on a slimy quality.
Soft Flesh Of The BulbUnder the papery outer layer of the onion bulb is the part of the onion bulb we use, the scale leaves. This part is often referred to as the flesh of the onion.
A fresh onion will have scale leaves that are firm and easy to slice. The bulb of a healthy onion will be hard, and if you gently press the bulb it will not give way to the pressure, but rather will remain firm.
Once the scale leaves become soft, you lose that crisp crunch of the onion. As the onion gets more decayed, it will become softer and eventually become mushy. At this point it will be impossible to slice.
While you may still be able to use an onion that has just begun to lose its crispness, you will not be able to use an onion that has gone mushy. You will have no alternative but to throw it in the compost bin.
Shrivelled, Drying FleshA second indicator that your onion is on its way out is when the flesh of the bulb starts to shrivel and dry out. The scale leaves will actually shrink in size.
The extreme state of this decay will actually produce dry powder. At this point the onion is way past being able to do anything with and will never sizzle in a frying pan, grace a salad, or appear in a soup.
How To Know When An Onion Is Bad: Texture?

How To Know If An Onion Is Bad: Smell?

An onion has a pretty distinctive, strong smell. Cut into one, and boom, you are hit with that strong, characteristic onion smell which translates into fabulous flavor

When an onion is bad it will have a strong, pungent flavor and it will not be pleasant. You might liken it to the odor that comes from the stuff in your compost bin. If it smells ‘off’ to you, throw it out.

Bad OdorA fresh, healthy onion has no scent before it is cut open. Once you take a knife and slice it open, you are hit with that strong, onion smell. There is nothing off-putting about the smell.
When an onion is past its prime, you can smell it even before you cut it, and when cut, the smell is strong, and not in a good way.
The best way to describe the scent of a bad onion is “rotten.” It just smells bad, and kind of like the smell that hits you when you open your compost bin to add something.

All of these signs together will tell you that your onion is not good, that you should not use it, and it is best to throw it out. Here is a quick, at-a-glance chart to use to determine if your onion is beyond usable.

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Quick Chart: How To Know If An Onion Is Bad?

Spoilage Signs
Soft Flesh
Shrivelled, Dry Flesh
Limp, Wet Outer Layer
Bad Smell

Frequently Asked Questions

How Can You Get The Smell Of Onion Off Your Hands?

As much as we love the fabulous flavor of onions in our cooking, we really don’t want the smell on our hands. Fortunately, there are simple ways to get rid of that odor.

Here is a list of items that can be used to get onion smell off your hands. Just pour some onto a damp washcloth, and apply it to your hands. Scrub well, and use lots of water.

  • Vinegar
  • Lemon juice
  • Rubbing alcohol
  • Celery juice
  • Tomato juice
  • Mustard
How Can You Get The Smell Of Onion Off Your Hands?

Is There Something You Can Do To Minimize Crying When Cutting An Onion?

You can hold an uncut onion close to your eyes and nothing will happen, but as soon as you cut into it, you start weeping.

That’s because slicing the onion results in the release of something called allicin which gets into the air and comes in contact with your eyes. The tears you cry are actually your eyes trying to get the allicin out of your eyes.

There are two simple ways to combat the tears. The first is to make the onion cold. Pop it in the freezer for 30-45 minutes or in the fridge for a minimum of 2 hours.

The second thing to do is invest in a pair of goggles and slip them on whenever you cut onions. You’ll look a little odd, but your eyes will stay dry!

What Is The Best Way To Store Onions?

For fresh, whole onions that have not been cooked, think cool, dry, and dark. While the fridge is dark, it is also cold – too cold for onions for peak storage, and it is humid.

Tucked away in a cupboard, or in a cellar are two good options. The onions should be left with their outer layer on, and can be placed in a mesh bag, but should not be put in a plastic bag.

The plastic will create moisture, and moisture speeds up the decaying process.

Keeping a handful of onions on the counter for a couple of days is also totally fine.

However, because the onions will be subjected to light when they are sitting on the counter, this will cause them to sprout if they are left there too long. The onion bulb is living, and light tells it to grow!

What Is The Best Way To Cut Onions?

For years I would chase little slices of onion around on a cutting board, trying to get all of the pieces chopped. I also got more than one cut from the process.

If you’re like me, and are looking for a safe and easy way to successfully cut onions, you will be glad to know there is a better way!

  1. With a sharp knife cut the root section and the top off the onion. They can go in the compost bin.
  2. Stand the onion on its root end, and make a vertical cut from top to bottom, slicing the onion in half.
  3. Peel off the outer papery layer, and put it in the compost.
  4. Place one half of the onion on its cut side.
  5. For onion slices simply cut a series of half moons across the length of the onion. As you get to the end of the onion, flip it onto the larger cut side for easier slicing.
  6. For chopped onion, hold the onion half in place with your hand on the top, then slice through the onion half almost to the root, but not all the way through. Make about 3-4 slices, depending on the thickness of the slices you want, and the size of the onion.
  7. Turn the onion and make vertical slices to the root, but not cutting all the way through.
  8. Turn the onion again, and chop across the onion, producing perfectly diced pieces.

How Do You Store Sliced Or Cut Onions?

Having extra sliced or chopped onions is wonderful! You can keep them for the next time you make a recipe calling for chopped or sliced onions and it will really save you time.

The thing to remember, however, is that once an onion is cut its storage life is reduced. Pop the extra chopped or sliced onion in a plastic bag with a zip closure or in an airtight container and put them in the fridge for 5-7 days. 

You can also put those slices and chopped bits in the freezer for up to 6 months. Just plan on cooking them up as they will not be great thawed and then put in a salad.

Jess Smith


Thursday 23rd of November 2023

Thank you very much for sharing, I learned a lot from your article. Very cool. Thanks. nimabi

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Sunday 4th of June 2023

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