Do Onions Go Bad? Ultimate Storage Guide

As most recipe calls for an onion, this is an ingredient that you are sure to have stored in your pantry.

However, have you ever wondered what to do with leftover sliced onions or question how long do onions last?

This guide will explore the best ways to keep onions fresher for longer and explain how they can go wrong.

Can Onions Go Bad?

Although onions can stay fresh for months, they can go bad over time, and it largely depends on how you keep them stored in the first place.

While there’s no guaranteed way for onions to stay fresh beyond their best before date, there are ways to keep them stored correctly and preventing the onions from going bad.

How To Know If An Onion Is Bad?

The clearest and obvious sign to look out for is by looking for dark brown or black spots on the skin’s outer layers, which indicates the onion has gone bad and is on its way to completely dry out.

As a result, this onion will soon be rotten and unusable. It should be discarded because it’s unsafe to use.

Indications for the best and most fresh type of onion are that they are firm outside with no spots or discoloration.

More signs that an onion as has gone bad:

  • You need to peel multiple layers
  • Onion mold
  • Soft or mushy on the outside
  • Completely dried out

Do Onions Go Bad If Not Refrigerated?

While whole onions shouldn’t be stored in the fridge and instead should be stored in a dry environment to keep them fresher for longer, sliced or cut onions behave a little differently.

When you cut an onion and have leftovers, you should keep them stored in an air-tight container or plastic bag and stored in the fridge to keep them fresher for longer.

Otherwise, they will go bad very quickly because they will dry out, and mold will soon grow.

Do Onions Absorb Bacteria?

Leaving sliced onions out and exposed to air will go bad quickly, as with most other foods.

However, there’s a common assumption that onions absorb bacteria, but studies show that there’s no real evidence to prove that sliced onions absorb germs or rids the air of toxins/poisons.

You may have seen “remedy hacks” online which claims onions can stop a cold or flu which is backed up with no evidence or studies.

How Long Do Onions Last

Fresh whole onions will typically last up to 2 months or longer when you follow the correct storage methods of keeping them stored in a cool environment, like a storage cupboard.

Sliced onions can last up to 5 to 7 days when stored in the fridge and in an air-tight container, while cooked onions will keep well up to 3 days when stored in an air-tight container in the fridge.

If you have a large bag of onions stored in your cupboard, it’s advisable to check them regularly because if one has gone bad, it can contaminate the surrounding onions which means you will need to throw them out.

How To Store Onion

By storing onions correctly will keep them fresher for longer and can prevent them from going bad and contaminating the surrounding onions.

Whole onions can last for 2 months but in some cases it could be longer depending on how they are stored.

How to Keep an Onion Fresh

Keep the onions stored in a cool environment like a cupboard – avoid storing them under the oven or under the sink as a result.

Onions are often purchased in a netted bag which allows the air to flow, which is how you would want to ideally keep stored in your pantry.

How to Store A Cut Onion

When you have leftovers from a sliced onion, you can keep them stored in an air-tight container (or onion keeper) or plastic bag, and stored in the fridge.

This will keep the onion fresher for longer. However, if you keep it stored at room temperature, it will go bad quickly and might only keep well for a day.

How Long Do Cut Onions Last?

When stored in the fridge and in an air-tight container, sliced onions can last for up to 5 to 7 days which you can reuse for your recipes.

Keeping them stored in an environment which is air-tight as possible will impact on how long it will last too.

For example, we have noticed that storing sliced onions in plastic zip-lock bags always guarantees to stay fresh for at least a week.

Leave a Comment