In the Bon Appétit test kitchen, we’ve been up to our elbows in tasty fried food lately. And while we’ve got no complaints about having beignets and buffalo wings hanging around, we have been going through quite a bit of oil. Like a lot of you, we don’t have a deep fryer in the kitchen. Instead we use a heavy pot (like a Le Creuset Dutch oven) fitted with our new favorite OXO deep-fry/candy thermometer and filled with the best oil for frying. It’s a great set-up for home-frying but it also means we’ve got a lot of used oil to think about. In an ideal world, we would use fresh oil every time we wanted to fry and would recycle our old oil to fuel our Magic Bus as we head north to chase rainbows and forage for mushrooms. Well, we don’t have a bus and, as test kitchen manager BA Brad will remind you, we’re on a budget. So we try and reuse our oil once, maybe twice, depending on what we’re frying.
If it’s not used, cooled, or stored properly, oil can develop harmful free-radicals (bad-for-you atoms that have been found to lead to cancer and heart disease). This happens when the oil is exposed to excess oxygen, which happens naturally when food is fried. You know all those bubbles that happen when you drop the food in? That's what we mean. Excess oxygen exposure can lead to rancidity, an unpleasant odor and nasty flavor. To avoid all that and get the most out of another frying session, here’s how to deal with the hot stuff:
When you’re finished frying, turn off the heat as soon as possible and allow the oil to cool completely. I mean it—cool it completely. Oil burns are awful (trust me) and it’s not worth the risk just to clean up the kitchen before bed. Come back when you’re sure the oil is cooled to room temperature.
Pour the used oil through a fine-meshed sieve lined with a couple layers of cheese cloth. This will help catch any of that fine matter left behind after your first fry. While it’s tempting to leave those behind, those little bits will burn and make the oil taste nasty when reheated. It's best just to strain them out as soon as possible.
Transfer the strained oil into a clean container—we like a glass jar but you can use the bottle the oil came out of if you remembered to save it (you did, didn’t you?). Use a funnel to help make the process neater. Store the oil in a cool dry place. That means not close to the oven, or over the fridge or microwave (it gets hot up there!).
There are a couple of things to keep in mind if you plan to reuse your oil. First, the oil takes on the flavor of whatever you fry in it, so fry similar items in previously-used oil. For example, don’t fry your favorite cinnamon donuts in yesterday’s catfish oil. Don’t fry today's falafel in yesterday’s Korean Fried Chicken oil. You get the idea.
Second, mind your order of operations. Vegetables tend to have the lowest impact on your oil and leave the least amount of flavor and debris behind. Batters tend to stay put on their vehicle, and you can usually skim off any crispy droplets that didn't stick. Breaded items, however, especially those with a fine coating of flour or cornstarch, tend to leave lots of little particles in their wake. As they sit in the bottom of your pot, even as the oil cools, they’ll continue to cook and eventually burn and infuse the oil with a bitter flavor. Save those for last and make sure you strain the oil when you’re through.
Remember, once your oil is caput, don't pour it down the drain. That’s bad for your pipes and bad for the environment. Do place it back in that resealable container and throw it away. For bonus points (and good oil karma) use this handy site to find out where you can recycle cooking oil in your area.