I Cut More Onions Than I Needed—Here’s How to Store Cut Onions in the Refrigerator

Extra cut onion has a place in your refrigerator.

Hello dear readers! Today I'm going to talk about how to preserve or store cut onions in the refrigerator, including chopped or sliced ones. This usually comes up for me when I've started cooking or meal prepping and then realize that the onions I've chopped are more than I'll use in my recipe. I like cutting all the vegetables I'll need for cooking once and for all, especially onions, because I really don't like cutting vegetables. I dream of having those perfect vegetable cutters that can actually do justice to my veggies. That's why I usually chop what I feel is more than enough, so I don't have to stop in the middle of cooking to go back and slice more onions.

Of course, that sometimes leaves me with extra onions after cooking. There it is, that leftover onion sitting on the cutting board, looking like something I'll definitely use tomorrow. Instead of leaving it out until it becomes soft or throwing it away, I simply put the leftover chopped onions in the refrigerator. Storing cut onions is actually pretty simple. The main thing is to keep them covered and refrigerated so they stay fresh, don't dry out too quickly, and don't make everything else in the fridge smell like onion. And if you like doing a little meal prep like I do, you can even chop onions ahead of time and keep them ready for your next few meals.

In This Article:

• How to Store Cut Onions in the Refrigerator
• How to Store Chopped or Sliced Onions
• Can You Freeze Chopped Onions?
• Can You Store Cut Onions Without a Refrigerator?
• How to Tell If a Cut Onion Has Gone Bad

Should You Refrigerate Cut Onions?

There's quite a difference between a whole, unpeeled onion and an onion that has been cut open. The inside of a whole onion is protected by its dry outer layers, which is why it is usually stored somewhere cool, dry, dark, and well ventilated rather than in the refrigerator. Once you peel, cut, slice, or chop an onion, the inside is exposed, and that prompts a change in storage method.

The National Onion Association recommends keeping cut onions in a sealed container in the refrigerator. Its guidance says properly refrigerated chopped or sliced onions can be stored for about 7 to 10 days. So if you only used half an onion for dinner, you don't have to cook the other half immediately just because you've already cut it.

How to Store Cut Onions in the Refrigerator

Put the cut onions into a clean, sealed container and refrigerate them. That's really all there is to it.

1. Use a clean, airtight container

The leftover onion storage container you're using should have a lid that closes tightly. We all know how strong onion odors can be, and how easily they can permeate other items nearby, like your leftover rice, cheese, fruit, or other foods in the fridge. We want to keep that onion smell locked inside a sealed container. Sometimes I run out of airtight containers because they're already in use for other things, so I opt for a clean, resealable food-storage bag. 

2. Store the onion as you cut it

Don't change the shape of your cut onions just because you're saving them for later. This means if the leftover or extra onion is halved or sliced, put it in the storage container in the same form and store it. No extra cutting just for storage.

3. Refrigerate it promptly

After you're done slicing what you need, don't leave the portion you're saving out on the counter. Cut produce shouldn't be left sitting at room temperature for hours. The official rule of thumb from the FDA is to refrigerate cut produce within two hours. If your kitchen is hot—say, above 90°F (32°C) during the summer—that safety window shrinks to just one hour. Bottom line: if you know you're done with the rest of that onion, pack it up in its container and put it in the refrigerator promptly.

4. Keep your refrigerator cold enough

For safe cold storage, keep your refrigerator at 40°F (4°C) or below. Not sure how cold yours actually gets? Use a refrigerator thermometer to help you determine that. Place the container holding the cut onions on a regular refrigerator shelf, preferably the middle shelf. You don't need to keep it in the door, since the temperature there can fluctuate more often.

Also Read: How to Organize Your Fridge for Maximum Freshness and Food Safety (Step-by-Step Guide)

How to Store Chopped or Sliced Onions

Chopped and sliced onions follow the same basic storage method I've already mentioned previously. Put the amount you are yet to use into a clean, sealed airtight container and refrigerate it. If I know I'm going to make stew, soup, fried rice, sauce, or another dish that needs onions in the next few days, having some already chopped saves me some time.

And as for whether you should wash onions before storing them in the refrigerator, you don't have to. You can wash the onion when you're ready to prepare it for cooking. For storage, what matters here is using a clean container and keeping the prepared onion refrigerated and sealed. Also make sure your knife, cutting board, hands, and other preparation surfaces are clean. Onions should not be prepped on an unwashed cutting board that has just been used for raw meat.

Can You Freeze Chopped Onions?

Yes. Freezing is another option when there's much more chopped onion than you can use within the next several days, or you're just innocently meal prepping ahead. The National Center for Home Food Preservation says cut onions can be frozen for cooking, but freezing changes their texture (that's for sure). That makes frozen onions more preferable for cooked dishes than for recipes where you want the crisp texture of fresh raw onion. Divide them into portions you'll actually use if you're freezing a large amount. That way, you don't have to thaw the entire batch just to get a handful of onions.

Can You Store Cut Onions Without a Refrigerator?

You can't do that for extended storage. A cut onion can sit out briefly while you're preparing a meal, but once you're finished with it and plan to save it for later, refrigeration is the better option. There's one thing I do when I only want to use part of an onion. Instead of cutting it, I'll use my fingers to carefully peel off the amount of onion flesh I need without creating a cut section. If the flesh is too tapered, I'll first use the pointed tip of a knife to scrape a small part off, which gives me a better starting point to peel the rest.

Afterwards, I'm left with an onion that still looks whole and uncut. I'll use the papery outer skin to cover the exposed part, or simply place it on top of the rest of my unused whole onions, which I store in a cool, dark, and dry place. Of course, I make sure to use it again within about a week, and it will still be fresh. I usually do this when I only need a little bit of onion for a quick, easy meal that I'm going to finish immediately. It saves me from cutting open an entire onion when I only need a small amount.

How to Tell If a Cut Onion Has Gone Bad

The storage time is important, but your onion can also give you clues as well. These are the things you should watch out before using a refrigerated cut onion:

• Slimy or unusually slippery texture. A little moisture isn't automatically a problem, but a distinctly slimy surface is a reason to discard it.
• Mushy or very soft spots. Fresh cut onion should still have some firmness.
• Mold. If you see mold, don't try to rescue the rest of the onion.
• Strong unpleasant or sour odor. Onions naturally have a strong smell, so you're looking for a smell that seems wrong rather than simply oniony.
• Significant deterioration. If the onion looks noticeably degraded, it's better to throw it away.

The storage period is a guide, not a reason to eat an onion that has clearly spoiled. FDA guidance also advises avoiding foods that develop an off odor, flavor, or texture.

Also Read: How to Store Onions: Expert Tips to Prevent Sprouting and Spoilage

Should I store a whole onion in the refrigerator?

Usually not if it is a whole, dry, unpeeled storage onion. Instead, it should be kept in a storage basket and placed somewhere cool, dry, and well ventilated. Whole peeled onions should be refrigerated, or you can use the little peeling trick I mentioned earlier when you only need a small amount and want to leave the onion looking whole.

The Next Time You Cut Too Much Onion

You can now go ahead and store cut onions in the refrigerator without asking how the next time you cut an onion and accidentally chop more than you need. Put the extra onion in a clean, sealed container and get it into the refrigerator. That little leftover onion can become the starting point for whatever you're cooking next. And if you find yourself doing this often, you might even start chopping onions intentionally as part of your meal prep. Make the next cooking session a whole lot easier with just a few minutes of preparation. Just remember that having the cut onion sealed up properly is a way to extend its freshness while also containing that strong onion smell.