Question: When I place fresh, uncut tomatoes in the same bowl as uncut onions for storage, the tomatoes rot very quickly.
Why is this?
Answer: Here is our best Alton Brown impersonation:
“Welcome to the wonderful world of ethylene gas.”
Fruits and vegetables continue to change after they are picked, ripening and — eventually — rotting. Part of that process is emission of ethylene gas, a naturally occurring substance produced by most fruits and vegetables.
Tomatoes produce a lot of it, which is why you can speed ripening by placing a tomato in a closed paper bag to trap the ethylene.
Onions also give off a little ethylene. When you put the tomato and the onion together, you increase the presence of ethylene, to the detriment of both.
To reduce the ethylene, don’t store onions and tomatoes together. (Onions will make potatoes get soft, too.) You don’t have to put them in separate rooms. A few feet apart will do it.
It won’t look as much like a still-life painting on your counter, but your tomatoes will be much happier without the onions.
And your onions will be happier in a dark, well-ventilated place, such as inside a cupboard.
