Onions infuse our recipes with their irresistibly sweet, smoky aroma and it is easy to buy more than you can reasonably use. If you are wondering ‘does onion go bad?’ this article will explain everything you need to know including shelf life and tips on making your onions last longer.
Table of Contents
Does Onion Go Bad?
Many people tend to think that onions, with their tough skin, do not go bad or at least can go for years without spoiling.
The truth is, onions can go bad if they are not stored in the right conditions and if they stay unused for too long. Moisture is onions’ biggest enemy. Whether you store them in the pantry or fridge, whole or cut, onions will lose their freshness fast if they get into contact with any kind of moisture.
We’ll learn more about ways to store them, but first, let’s take a look at the shelf life of onions.
How Long Does Onion Last?
How long onions last depends on how they are stored, their age, and whether they are whole, cut, or cooked.
Whole onions can last up to 3 months as long as they are stored in a cool, dry, and dark place, preferably in the pantry. But, when onions are kept too long, even in the right conditions, they will begin to dry up and will eventually shrivel.
You should still be able to eat old onions but chances are good that you’d have to discard several layers before getting to the fresher core.
You can keep whole onions in the fridge for about 1-2 months but this might not be the best use of fridge space. Also, in the fridge, they can easily get moisture and will go bad pretty fast from there.
Cut onions have an even shorter shelf life and will stay in the fridge for about 1 week before their quality begins to deteriorate. For best results, you should store cut onions in an airtight container and limit the number of times you open the container.
Storing cut onions in the freezer can extend their life span by 5-8 months but they will end up being soft and soggy once they thaw.
Lastly, if you cook your onions, expect them to last 2-3 days in the fridge after which they will begin to spoil.
Onion Shelf Life
|Whole onions||1-3 months||1-2 months||
|1 week||5-8 months|
|Cooked onions||2-3 days||
4 Tips To Tell If Onion Has Gone Bad
Whether whole or cut, there are a few unmissable signs of a bad onion. Here is what to look out for:
The first sign that onion is going bad is the formation of black or brown spots on the outer skin. This happens when whole onions have stayed too long. Unless it is squishy and smelly, it probably has a few days before you can discard it. We recommend peeling, cutting out any discolored spots in the inner layer, and using up the onions as soon as possible.
Mold is a classic sign of spoilage in any food, including onions. Mold will form on the surface of onions that have been exposed to moisture.
But, before you throw out molding onions, check for other signs of spoilage such as discoloration, an off smell, and squishiness.
If it is just mold, you can extend the shelf life of the onions by wiping off the mold using a dry cloth and storing it in the fridge until you are ready to use. It is best to use molding onions soon or else they will collect moisture in the fridge and begin the decaying process.
Whole or cut onions have a distinct smell. An onion that starts to smell off will usually have other signs of spoilage including discoloration, leaking, and feeling soft to the touch. In this case, it is time for those onions to go.
Cut onions that have been left out at room temperature for over two hours may not show the classic signs of spoilage but it is best to discard if they have not been refrigerated for that long.
Cooked onions that have gone bad will have a fishy smell and look slimy. We do not recommend tasting cooked onions that are over 3 days old.
4. Drying and sprouting
When onions stay in the pantry too long they may start to sprout and there is nothing wrong with eating the onion. However, soon after sprouting, the onion may become squishy and then start to shrivel up and it will have lost its freshness.
5 Tips To Store Onion
Like most fresh vegetables, onions need to be stored in the right environment to maintain peak freshness.
Follow these tips on how best to store your onions to get the most out of them:
1. Keep them away from moisture
Moisture creates the perfect breeding ground for bacteria and mold. If you want your onions to last for months, store them in a dry pantry. Avoid keeping onions in other common storage locations such as under the sink or in the basement where it is humid and damp.
2. Get the temperature right
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.
3. Store away from other foods
Have you ever wondered why fruit and vegetables when stored together in close quarters ripen so fast? This happens because of ethylene, a ripening chemical compound found in some foods.
In particular, try to store onions separately from potatoes, tomatoes, apples, melons, and bananas. Ethylene from these foods will ripen the onions, causing them to become mushy.
Sliced or chopped onions lend themselves well to refrigeration compared to whole onions. In fact, you should avoid storing uncut onions in the fridge—the coolness will cause them to lose their crunch and they will eventually become too soggy to reasonably use in the kitchen.
Use a slicer or food processor to cut your onions into small bits. Then, pack the cut up onions in freezer bags in small portions that can be used in one go. Flatten each freezer bag to remove air bubbles and to make it easier to stack them in the freezer.
5. Use the right packaging
Onions come in those meshed bags for a reason—to ensure adequate airflow and keep moisture at bay. If stored in the pantry, onions should be kept in these meshed bags or a brown bag with a few holes in it. Avoid keeping whole onions in plastic bags where they will accumulate moisture and eventually go bad.
The Risk of Consuming Expired Onion
Eating onions that have gone bad is not a good idea. First, moldy, smelly, squishy, or discolored onions will mess up the flavor and aroma of any recipe.
In addition to this, like any other organic food, bad onions can be a breeding ground for harmful bacteria. In one instance, the Centers for Disease Control and Prevention recalled onions contaminated with the salmonella bacteria.
Salmonella is a leading cause of food poising and people infected with the bacteria may develop stomach ache, fever, and diarrhea. These symptoms can last up to one week. Children, the elderly, and those with a weak immune system are more likely to have a serious illness caused by eating contaminated onions.
Can You Freeze Onion?
If you have too many onions on hand or you just want to prepare them ahead, freezing might be a good idea.
Frozen onions can keep up to eight months but expect them to lose their crunchiness and distinctive flavor if you store them this way for too long. It is best to freeze onions no longer than one month especially if you still want some crunch in them when thawed.
Follow these steps and tips to freeze your onions:
- Peel and slice or chop. Do not freeze whole onions—they cannot withstand extremely cold temperatures and will turn into a squishy messy upon thawing. A neat trick is to cut up the onions into thick slices to keep them from becoming too mushy when thawed.
- Store the onions in freezer bags in small portions that can be used in one go. Onions do not refreeze too well. Be sure to squeeze out as much air as possible to ensure that the onions stay dry. Place in the freezer until you are ready to use.
- Try to use the frozen onions in no more than three months for maximum flavor.
Once thawed, you can use your pre-cut onions in stews, for sautéing, and even as a pizza topping.
Compared to other vegetables, onions are quite hardy. Stored under the right conditions, they can maintain peak freshness for several months.
Still, you should always keep an eye out for signs of spoilage because one bad onion can quickly affect the rest of the bunch. Remember to immediately refrigerate cut onions and to discard any that have been out too long or lost their freshness.