Have you ever cut into an onion, peeled off the skin, and then discovered that it is brown on the inside? This is not a nice thing to find, and it might make you wonder whether the onion is still okay to use, and why this happens.
Onions can go brown inside because a bacterial or fungal infection has got inside the bulb and rotted that layer of the vegetable. This infection is often impossible to see from the outside, but will be very clear when you cut the onion open.
Let’s find out why onions go brown inside and whether this makes them unsafe to eat. If you find an onion with brown layers, you need to know how to handle it!
Why Are My Onions Brown Inside?
Onions usually go brown due to a bacterium or fungus attacking a layer of the flesh. This may sometimes spread across multiple layers and could ruin the onion completely if it has been left to grow for long enough. Sometimes, it will be caused by mechanical damage during harvesting, while at other times, it is just a result of the onion being in the field for a little too long.
In rarer cases, browning inside your onion may be caused by something called internal dry scale, which occurs when the weather is very hot and dry. This happens when the developing leaves on the onion die because they aren’t getting enough water.
When water is restored to the plant, it will grow new leaves over the dead ones, but these dead ones can provide an entry point for bacteria and fungus, and may result in browning inside the onion.
Which Bits Of The Onion Are Safe To Eat?
You shouldn’t eat the brown part inside the onion. It may contain bacteria or fungal spores that could make you sick if you consume them. Cut this part out and do not use it in foods, even if you wash and cook it.
However, you should be able to safely cook the rest of the onion as long as the flesh is still white and firm. Cut the brown part away and consider removing another layer or two to ensure that there is no contamination, and then the rest should be safe to consume.
If you find that a large portion of the onion has gone brown inside, you may wish to throw all of it away, as there is a greater risk of contamination. However, if only a small section has gone off, you can safely use the rest if you cook it.
There is currently little scientific evidence on this, but anecdotal evidence suggests that it should be safe. However, if the rest of the onion is mushy or has a strange, unpleasant scent, you should compost it, rather than consuming it.
Can I Eat Onions Raw?
It is probably best not to eat any part of an onion raw if it has started to develop brown bits. It may not be particularly dangerous, but there is certainly either bacteria or fungus in the flesh, and this is best avoided. Cooking should help to reduce the risk, but eating it raw may be unsafe.
If you cut an onion open for salad and discover that it is brown inside, use it for cooking and choose another onion to enjoy with your salad.
Can I Avoid Browning In Homegrown Onions?
If you are growing onions at home, the best way to reduce the risk of browning is to make sure you harvest the onions as soon as they are ready so that there is no opportunity for them to go off in the field. This also reduces the risk of them getting internal dry scale, because there is less time for the leaves to die.
You should keep an eye on your onions in the field and be ready to harvest them at the right time. Although onions are resistant to many pests and diseases, it still isn’t a good idea to leave them out for longer than is necessary.
Instead, bring them indoors and hang them up to dry. If any feel soft or mushy when you bring them in, make sure you cut them open and inspect them as soon as possible. If the flesh is still good, use the onion up.
Don’t leave onions that you suspect are going off with the rest of your crop; they may contaminate the whole batch.
Is The Brown Flesh Rotting?
In general, the brown indicates that the flesh is starting to break down, yes. The fungus or bacteria will have damaged the onion’s cells and this causes compounds within the cells to start interacting with each other – producing the brown color.
You may also notice that the onion has an unpleasant, rotting scent. This might be noticeable as soon as you cut into it, or only once you reach the brown layer. You may need to throw the whole onion away if the flesh is turning soft and smelly, so make sure you check.
Will The Rot Spread?
Often, the brown is confined to just one layer, and does not affect the others. It will spread through this layer quite quickly, but rarely through the rest of the onion. However, given enough time, it will eventually contaminate the remaining flesh and make it unusable.
If you think one of your onions may have rot in it, you should aim to remove this part and use the rest of the onion as soon as possible. Don’t wait and give the bacteria or fungus time to spread.
Is Onion Browning Common?
Onion browning is relatively rare, but you are likely to see at least a few onions that suffer from it in your lifetime, especially if you grow your own onions.
Stores and farmers make every effort to reduce this issue and avoid selling onions with bad centers, but because it is hard (or impossible) to detect from the outside, it is bound to happen sometimes.
Onions go brown inside when the flesh has been infected by a bacteria or fungus, usually getting in through the leaves at the top of the onion. It is normal for only one layer to be affected, and the rest of the onion should be safe to cook with.