How can I store chopped onions in the fridge without the smell?

I regularly store chopped onion in my refrigerator (or at least halves & quarters).

I either use tight-sealing plastic containers or zip-top bags. You may want to double-bag in zip-tops to be sure to avoid a smell.

One problem you may be having is onion-ness getting on the outside of the container. Be sure the outside is all clean and dry - no point in having a nicely sealed packet of onion when the outside can get all stinky anyway.

The issue is onions have chemicals in their cells that merge to form the compounds that we're used to. First, you need to minimize the damage you do to the onion, as you're otherwise releasing the chemicals too early. This means for the most part using a very sharp knife.

Depending on what you're going to be making with the onions, you can put them in the freezer instead of the fridge (but that's generally not needed for this short of a time if you use one of the other recommendations below); if the onions are going to be cooked, you likely won't notice the difference in texture. The cold helps to slow down the chemical reaction.

And your last option is to change your onions -- consider 'sweet' varieties of onions, or red onions, that aren't going to have as strong of an onion flavor, but also won't outgas as much as a result.

And um ... use a glass, corningware or similar container, with a tight fitting lid. I find the smell seems to permeate through plastic over time. (it might not be an issue for only 6-8 hours, but you never know).

And the last option -- don't finish chopping them. Halve them, peel them, and store 'em cut-side down in the fridge, so you've already reduced maybe 1/3 the time to chop onions (assuming you have sharp knives and good knife skills), then just finish 'em at the last minute. Maybe recruit a second person to help.

Store them in sealed containers, in water. This has the extra advantage of ameliorating the harshness of the onion.

Jacques Pépin recommends just rinsing the chopped onions, as this will remove chemicals produced by chopping the onion that are responsible for the smell. This was featured on an episode of "More Fast Food, My Way". The episode was "Viva Espana!", episode #201 at about 10:10 into the show. http://www.youtube.com/watch?v=G4YahBNTHdc

This is a well-known 'thing' with onions and the solution is this:

Salt them lightly before storing. (You can compensate by modifying the salt in the dish you're going to use them in.) I'm sure it has a scientific basis, but I don't know it - Mediterranean housewives have known this for hundreds of years. Good luck.

Foolproof method of storing onions in the fridge without the smell permeating inside and also into the container which it is stored is....To store it in a glass bottle with a tight lid like a jam bottle.

How about just skinning the onions as prep? Storing these will not be create as much smell and then when you need them take them out of the fridge and use a food processor to save time chopping them.

I always wrap my onions, sliced, chopped or otherwise, in aluminum foil. Never have a problem with odors in the fridge.

I have been storing onions in a glass cup that has a nice secure lid. The onion smell does not infiltrate the fridge, but it's impossible to get the smell out of the lids.

Drop'em in boiling water for 5 seconds. Place them in a ziploc-style bag an remove as much air as possible. I guarantee zero smell will permeate your fridge. And 100% of their juicy aromatic essence will be retained. Even a week later.

Coat the chopped onions in a bit of the cooking oil you'll be using.

You're using onions for flavor and not as a garnish, so just use dehydrated onions instead. The one exception is onions in salsa, when you need the soft crunch and the explosion of onion flavor mixing in with the other fresh veggies. (That's why homemade salsa ALWAYS beats store-bought.)

In my Los Angeles restaurant I've always used powdered onion, garlic, cumin, etc. whenever possible.