Ever peel back the dry outer layers of an onion and find a softer, brown layer in between perfectly fresh rings of onion? Sure, we all have. But what do you do next? Read on to find out what you should be doing when your onion has a brown ring.
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Onions are a staple of our kitchens and a foundational ingredient in nearly every cuisine across the globe. As such, we often stock up on onions in bulk for our cooking. But while these hardy vegetables can be stored for a long time, they can go through some changes as they age that might give you pause before cooking with them. But not all changes are bad or dangerous, so before you throw your onions away, check our handy tips below!

How to select a good onion

To begin, start by buying the best onions you can find, since they will last the longest and be the best quality. Good onions are firm, like a baseball, and have a tight papery exterior layer. They should not have a loose paper layer or feel soft. They should also feel heavy for their size. Lighter onions have begun to dehydrate and will not last long or taste as good, and their texture suffers in both raw and cooked applications. The stem end should be dried out and not show any signs of green sprouts. And you should not see any bruising, brown or black spots, or obvious mold. 

How do I know if an onion is bad?

Onions, while known as a stinky vegetable to begin with, will give you a definitive odor that indicates they are bad. Fresh onions will always smell of onion, even strongly, but bad onions will smell like rot or compost, or have a sulfurous, acrid smell that is a good indication things have gone off. If they smell like garbage, put them in the garbage. If you see green or brown powdery mold on the onion, discard the onion, since those spores can get into the bulb, even if you peel away the exterior.

an onion half with a brown ring
Credit: Getty Images / xxmmxx

Is it safe to eat an onion with a brown layer?

Sometimes an onion might feel and smell totally fine, but when you cut into it, you see that one or two of the rings have gone brown and might be a bit mushy or slimy. While not appealing, this layer is not an indication that the whole onion is bad, and it is not dangerous to the rest of the bulb. As long as it does not have that intense rotting smell, you can safely remove the affected layers and continue to use the parts of the onion that are white. 

How do I know if an onion is moldy?

On the outside of an onion, mold is usually green or black and can be either powdery or sticky. On cut onions, mold will more likely appear as thin, white, threadlike spores. In either case, moldy onions should be discarded, as they are not safe to eat even after cooking.

Try this recipe: Melting Onions

Is it safe to eat sprouted onions?

If you see green sprouts popping out of the stem of your onion, that does not mean the onion itself is unsafe to eat. Green onions or scallions are just these initial baby onion sprouts! You'll need to rely on other indicators to determine whether the onion itself is safe to eat. Since a sprout is using the bulb as a growing medium, it is "feeding" on the onion, so you may find when you cut into it that the onion bulb has become soft or brown, in which case it is not safe to eat. But if the onion inside is still white and firm, it is safe—as is the sprout! If the onion is not salvageable, you can cut it away from the sprout, leaving some of the root end attached, and place the sprout in a vessel with water and you will grow a full-size scallion in a matter of a week or so.