How to Store a Cut Onion

Refrigerating a Cut Onion

Keep your onion clean when preparing it for storage. Minimize exposure to harmful bacterial by preventing cross-contamination with uncooked meat and dairy products. Use separate cutting boards for meat and produce. Always wash your hands after handling uncooked meat and ensure that your knife is clean. If you have space, consider setting up dedicated areas for produce and meat preparation, so you don’t spread germs while cooking. Avoiding cross-contamination is especially important when preparing food for storage because storing food allows bacteria time to grow.

Wrap large pieces of onion with plastic wrap. If you have half of an onion remaining or a few large wedges, then wrap them tightly in plastic wrap. Plastic wrap will insulate the onion from the outside air while helping it retain moisture.

Place smaller onion pieces in an airtight bag. If you have smaller pieces of onion left over, use a resealable bag to store them. Never use cloth storage bags, as these are intended for whole produce and will not protect a cut onion from exposure to air.

Consider reusable containers if you have them. You can find airtight plastic containers for food storage at any big box store. These containers work great for refrigerating cut onions. There are also new, silicone products designed to stretch over and cover the exposed side of cut produce. Exercise caution when using these with onions. These products will not fully encase an onion, which can cause your refrigerator to smell.

Store onions in your refrigerator at or below 40 °F (4 °C). Cut onions should always be stored in your refrigerator—not at room temperature. Keeping them at a low temperature inhibits the growth of bacteria and allows you to safely reuse them later. Ignore any storage recommendations that suggest that cut onions can be stored at room temperature. Some common tips include storing onions in a bowl of water on a countertop. This approach only promotes bacteria growth.

Use or discard cut onions after 7-10 days. Try to reuse refrigerated onions as soon as possible. However, never use them if stored for over 10 days. Store all cut onions for the same period of time regardless of variety. Even though you may find different storage recommendations for different onion varieties—such as yellow, white, red, pearl, or Vidalia—these recommendations are relevant only for whole onions, not for cut ones.

Check if onions are fresh enough to use after storing. Throw away onions that appear cloudy, mushy, slimy, or moldy. Smell the onions to make sure there is no unusual odor, and if they give off an strong or unusual odor, dispose of them.

Plan to cook previously stored onions. Never serve previously stored onions raw. You’ll need to cook them first because the heat will kill off any bacteria that may have grown during storage.

Freezing a Cut Onion for Extended Storage

Chop the onion into small pieces. Large pieces of onion—like an onion half or wedges—do not freeze well. To freeze effectively, you’ll need to chop your remaining onion into small pieces, preferably⁄4 inch (6.4 mm) cubes. Smaller onions freeze more evenly whereas larger sections often become freezer burned.

Put the chopped onion into a freezer-safe container. You can use freezer-safe resealable bags. Alternatively, use a freezer-safe container made of either glass or plastic. Regardless of the type of container you select, make sure that the onion is spread out as thinly as possible. The thinner you spread the onion, the more evenly it will defrost when you’re ready to use it. You don't have to blanch your onions beforehand if they're chopped.

Write the date you cut the onion on the container. Either write the date legibly on the container itself, or write it on a label or piece of paper. Stick the date to the container. It’s easy to forget when you put something in the freezer. Having the date written on your onion container will ensure that you don’t lose track of when you stored it.

Store your onion in the freezer for up to 8 months. Even though your onion is frozen, it won’t last forever. Check the date before using it to make sure it has not been stored for more than 8 months.

Use previously frozen onion in dishes with soft textures. Frozen onion becomes soft and sometimes quite mushy when cooked. Use previously frozen onion for stews, soups, casseroles and other dishes where the onion’s soft texture will be less noticeable.

Add frozen onion directly to your pot or pan when cooking. Don't worry about trying to defrost your frozen onion before cooking. In fact, defrosting your onion before cooking will only lead to a mushier texture. If you only need to use a small portion of your frozen onion, and the pieces are frozen together, run the container under warm water until you can separate out the amount that you need.