Can You Store Onions in an Airtight Container?

If you have successfully grown a great crop of onions at home, the last thing you want is to lose some of your harvest due to improper storage. You might be wondering whether you can store your onions in an airtight container.

Whole onions should definitely never be stored in an airtight container. You might store chopped or cooked onions in an airtight container if you plan on refrigerating them, you plan on freezing them, or you are canning cooked onions in some way. You can also store dehydrated onions in an airtight container for long-term storage.

Read on to find out when you should definitely not store onions in an airtight container and under what circumstances it can be a good idea. Storing onions can be easy as long as you choose the right options for storing onions in each different scenario. You definitely should not always store onions in airtight containers. And it is often not necessary. But as you will discover, there is a range of scenarios where storing onions in airtight containers can be a good idea. 

Don’t Store Whole Onions in an Airtight Container

Many onions can be stored overwinter if they are stored correctly, even in an off-grid situation. First of all, it is important to choose healthy onions from your crop for storage – using up any blemished examples more quickly. It is also a good idea to choose onion varieties that are better for long-term storage. Some store better than others.

Harvest onions for storage at the right time. It is best to store onions that are fully mature and fully ripe. Harvest too early, and bulbs will be smaller and also harder to store. In contrast, if you harvest too late, it’s possible that your onions have succumbed to pests and other problems. When at least a third of your onions have foliage that is yellowing and flopping over, it is time to harvest your crop.

Once you have harvested your onions, leave them to cure. Ideally, temperatures should be between 77 and 86 degrees F. (25-30 degrees Celsius) for curing onions. Spread out the onions you harvested in a single layer. Leave them until the outer skins are crisp, the stems are not soggy, and the necks have tightened up.

Once they have dried and the outer skin is crisp, you can store your onions. But never in an airtight container. Onions must be stored in a dark, cool place. But not in a fridge. Ventilation and, crucially, dry conditions are key to making sure that stored onions last in top condition for as long as possible. Humidity is your biggest enemy when trying to store onions longer term.

The reason that it is a bad idea to store whole onions in an airtight container is that inside an airtight container, the humidity will typically be high, and of course, there will be no ventilation. Whole onions stored in this way will go off more quickly.

What is more, when onions are stored in an airtight container, this contains and concentrates the ethylene gas given off by the onions as they mature. This can also cause the onions to go off more quickly.

Store Raw, Chopped Onions in An Airtight Container

However, though storing whole, uncooked onions in an airtight container is a bad idea, there are a number of reasons why it might be a good idea to store onions in an airtight container. One example is if you have accidentally chopped too many onions for a dish and don’t want to cook them all right away.

Rather than wasting the leftovers, you can store them in an airtight container in your refrigerator. They can safely be kept there for up to 7-10 days before you use them.

A peeled onion can also be stored in your fridge for up to around two weeks in an airtight container.

Store Cooked Onions in an Airtight Container

You can also store leftover cooked onions in an airtight container. This is another great way to make sure you avoid food waste. If you store cooked onions in this way, they will be fine in your fridge as long as they are used up within around four days.

It is best to place the cooked onions in an airtight container in your refrigerator as quickly as possible, and for food safety, you should try to do so within two hours of cooking to make sure bacteria do not have a chance to proliferate as the food cools.

Freeze Raw, Chopped Onions in an Airtight Container

If you do not think that you will use up raw, chopped onions within 7-10 days, then you can also place them into the freezer.

The best way to freeze them is to place the chopped pieces onto a tray. Freeze them, then take the tray out of the freezer and place the frozen pieces into an airtight container. By freezing the pieces separately before placing them into an airtight container, you can make sure that it is easy to retrieve as many as you need whenever you want to use them and will not have to defrost the whole lot all at once.

When freezing onions, it is best to remove as much air as possible from the container, which can help keep the onions free from freezer burn and make sure that they taste good for as long as possible. Frozen raw onions will not be as crisp as they are when fresh. But they will be fine to use in a wide range of recipes.

Sliced or chopped onions can be stored in the freezer for around 3-6 months.

Freeze Cooked Onions in an Airtight Container

Of course, you can also freeze cooked onions in an airtight container or freeze a range of recipes with onions in them. These should also be just as delicious when defrosted as they were when they went in the freezer.

Again, just try to remove as much air as possible from the containers before freezing to get the best results.

The time that cooked onions can be stored in the freezer will depend on how they were cooked and any other ingredients in a recipe if you are freezing a complete meal. But typically, cooked onions on their own will be at their best in a freezer for around three months.

Canning Cut Onions and Storing in an Airtight Container

Pickling onions can also be a way to preserve onions at home. Pickled onions are placed into airtight jars along with pickling brine. Processing canning jars is safer for longer-term storage. Once open, pickled onions should be stored in the refrigerator, which will help them last longer.

Onions are low acid foods, and though they can be canned without vinegar, it is important to use a pressure canner and a recipe from a trusted source. Botulism is a very serious risk with low-acid foods like onions, so caution is essential, and pressure canning using a verified recipe is essential.

Onions can be pressure canned on their own. You can also can a range of onion recipes, such as relishes, chutneys, and other preserves.

Of course, canning jars are one type of airtight container. The airtight jars make it possible to safely store onions as long as the process has been followed correctly.

Storing Dehydrated Onions in Airtight Containers

Dehydrating onions is another way to preserve them. It is a good option for those who do not have the ideal conditions for traditional storage in a cool, dark, and reasonably well-ventilated space. Or for long-term storage.

You can dehydrate onions in a dehydrator, with a stove, or in the sun in warmer, drier climates. It is crucial to make sure that they are fully dehydrated and that no moisture remains. Make sure you cut the onion into even-sized pieces so they all dry at the same rate.

Dehydrated onions can be stored in spice jars/ mason jars or in airtight containers for long-term storage. They should not spoil but will lose flavor over time and may not taste as good after a longer period.

You can also grind dehydrated onions to make onion powder using a mortar and pestle, blender, or coffee grinder. Onion powder can also be stored in airtight containers.

As you can see from the above, though whole onions with skin on should not be stored in airtight containers, there are plenty of times when storing onions in airtight containers can be a good idea.

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