First, it’s best to wash produce right before you use it, because dampness encourages bacteria growth and therefore spoilage, food research scientist Amanda Deering of Purdue University told The Washington Post. The Food and Drug Administration recommends washing produce under cold running water — go ahead and wash your hands before and after you do the food, too. (If your bag of salad or other greens says it’s pre-washed, no further work is needed.) Scrub with a brush and/or gently rub the produce with your hands, depending on what you’re cleaning. Water is sufficient, so don’t use soap or bleach or even commercially made produce washes. In fact, the Department of Food Science and Human Nutrition at the University of Maine tested three commercial wash treatments and found that distilled water was just as effective or more effective at removing microbes and pesticides (you can use clean cold tap water instead of distilled).
Drying with a clean paper towel or dish towel can remove even more bacteria. And, yes, even if you don’t plan to eat the exterior of the fruit or vegetable, you should still clean the outside to avoid transferring contaminants from the surface to the inside.
Here are some more tips for washing specific types of produce.
Mushrooms: The conventional wisdom is that simply wiping mushrooms clean with a damp cloth or paper towel, or even a pastry brush, is preferable to rinsing them in water. That’s never a bad move, but know that you can safely rinse or dunk at least some varieties. White mushrooms are your safest bet. The good folks at Cook’s Illustrated, who test these kinds of things, found that a pound of white mushrooms only absorbed 1 tablespoon of water after being submerged in water for 1 minute. Oyster mushrooms, on the other hand, absorbed ¼ cup. The reason? Oysters, as well as varieties such as portobello and shiitake, have lots of gills, which can trap lots of water. Especially if you plan to roast gill-heavy mushrooms and need to ensure the water is driven off, you should stick with wiping them clean. In fact, Deborah Madison, in “The New Vegetarian Cooking for Everyone,” says she often finds that oyster, as well as enoki, mushrooms usually come out clean enough to not even need a wipe-down.
Berries: They’re expensive enough as it is, so to preserve their texture and flavor, berries are best washed right before you eat them. Sturdier strawberries can stand up to being rinsed in a colander under running water, but Better Homes & Gardens suggests that more delicate berries (blackberries, raspberries and blueberries) be set in a colander and then dipped in a bowl of water. After you’ve washed and drained your berries, you can dry them on a paper-towel lined baking sheet or in a paper-towel lined salad spinner. You’ll find some advocates for washing berries in advance in a vinegar-water solution to extend their shelf life and keep away the dreaded mold you often find when popping open a container. Here’s a primer from Food 52, if you want to go that route.
Root vegetables and others close to the dirt: Give root vegetables and tubers a good rinse and scrub with a stiff brush. (No, you don’t necessarily have to peel them.) Included in this category: potatoes, beets, carrots, parsnips, melons and radishes.
Leeks: Certain types of produce grow in layers which trap grit. Leeks are a primary offender. I like my colleague Bonnie Benwick’s method, which involves trimming the top and bottom of the leeks and then cutting them vertically in half. Stand them up in a container of ice water and let them soak for 15 minutes. You should see the grit drop to the bottom (as in the photo at the top of this story).
Greens and herbs: A water bath does wonders here, too. For salad greens (discard the outer leaves of lettuce or cabbage), Madison recommends swishing them in a large basin of cold water, with an additional five-minute soak if they’re especially dirty. Then, just lift the greens out and let the debris stay on the bottom. Dry the greens well in a salad spinner or with towels. This method works well for herbs, too. Because greens (chard, bok choy, spinach, collards, kale, etc.) tend to grow in sandy soil, Madison says you should take care to get all the gritty deposit off them. Her process: Trim, rinse under tap water and then do the same swish-and-soak as above, repeating the soak as necessary.
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