Mushrooms: The Water-Soaking Saboteurs
For quality reasons, do not wash mushrooms until you are ready to use them. Despite what many meal preppers think, scrubbing those earthy fungi days ahead is one of the fastest ways to turn firm, flavorful mushrooms into soggy disappointments. “All wild mushrooms should be washed and it is crucial to dry them out afterwards,” says Joseph Rizza, Executive Chef of Prime & Provisions in Chicago. “Cultivated mushrooms, like buttons and portobellos can be cleaned using a dry cloth or paper towel to wipe off the excess ‘dirt’ they are grown in.” The problem? “Certain kinds of mushrooms require washing but mushrooms soak up water quickly and become soggy,” he says. Think of mushrooms like tiny sponges that never learned when to stop drinking. “And fill a bowl with water first, then dunk mushrooms and quickly wash, they shouldn’t be in the water for more than 10-15 seconds,” he says. When you wash them too early for meal prep, you’re essentially waterlogging your future dinner before it even hits the pan.
Fresh Berries: The Mold Magnets
Strawberries are the only berry you should wash or prep (hull, slice, or dice) in advance, and perhaps only 1 day ahead. Blackberries, raspberries, and blueberries are all best to wash as needed; otherwise they can become soggy or moldy. Here’s the brutal truth about berries: they’re basically tiny time bombs waiting to explode into fuzzy, inedible messes. In 2022 and 2023, 10 people became sick and four were hospitalized with hepatitis A in California, Hawaii, Oregon, and Washington, after an organic strawberry grower in Baja Mexico sold contaminated berries, per the Centers for Disease Control and Prevention (CDC). There have also been previous recalls of blackberries, strawberries, and raspberries over norovirus fears, according to the FDA’s recall database. Washing berries too early doesn’t just make them mushy – it creates the perfect breeding ground for bacteria and mold. Rinsing your berries won’t necessarily remove all of the germs, but it can decrease the amount you’re exposed to, Dr. Russo says. The moisture from early washing becomes their enemy, turning what should be nature’s candy into nature’s science experiment.
Potatoes: The Sprouting Disasters
Potatoes: Peel or pare and chop up to a day in advance. Store in a bowl of cold water in the refrigerator. Even though this sounds reasonable, here’s where meal preppers go wrong: they think more time equals better prep. Vegetables that are best kept whole/uncut (due to rapid spoilage or color change): eggplant, tomatoes, white potatoes, cucumber and celery. Cut potatoes sitting in water for days don’t just lose their texture – they become nutrient-depleted shadows of their former selves. The same can’t be said for items like potatoes, apples, bananas, eggplant, parsnips, taro root, celery root, and avocados. As soon as they’re cut, the exposed surface begins to turn brown. You can limit the browning by brushing the cut surface with citrus juice, or you can try placing cut vegetables in water and fruit in acidulated water (water mixed with citric acid, citrus juice, or vinegar). But here’s the kicker: Cutting produce too early can cause a loss of nutrients and overall quality, as well. According to Verywell Fit, nutrient loss is caused by oxygen, light, and heat.
Leafy Greens: The Bacterial Playgrounds
Unless it’s prewashed, that is; studies have shown that washing prewashed greens at home actually increases the likelihood of getting sick due to cross-contamination. This revelation should make every meal prepper pause. Heartier greens such as collard greens, kale, Swiss chard, and beet greens can be washed and sliced or chopped 2 to 3 days in advance. More tender greens such as butter, romaine, red leaf, or green leaf lettuce can be washed 2 to 3 days in advance. But here’s what they don’t tell you: washing greens too early strips away their natural protective barriers. Washing produce too early can actually promote bacterial growth that can speed up food’s decay. It’s really best to wait to wash fruits and vegetables just before consuming them. Think about it – you’re essentially removing nature’s preservative coating and replacing it with… water and hope. Sometimes, raw fruits and vegetables contain harmful germs that can make you and your family sick, such as Salmonella, E. coli, and Listeria. CDC estimates that germs on fresh produce cause a large percentage of foodborne illnesses in the United States.
Onions: The Tear-Inducing Time Bombs
Onions: Chop or slice 1 to 2 days in advance, but keep in a tightly sealed glass container or a double-bagged resealable bag (if you don’t double the bags, your refrigerator will likely smell like onions and their aroma will infuse the foods surrounding them). But even with perfect storage, chopped onions become bacterial magnets faster than you can say “meal prep Sunday.” Peel the onions and garlic but don’t cut until you’re ready to use them in a meal. Cut onions immediately go bad as they attract the bacteria around the surroundings they are stored in, no matter whether they are stored in the refrigerator or in an open kitchen space. Here’s the science: once you break an onion’s cellular structure, you’re essentially ringing the dinner bell for every microorganism in your fridge. Onions release ethylene gas, a natural compound that speeds up the ripening process. When stored near potatoes, this gas encourages them to sprout and soften more quickly. The irony? The same gas that makes other produce spoil faster also signals the onion’s own decline once it’s cut.
Apples: The Oxidation Champions
Apples: If slicing a few hours in advance, store in cold water to prevent oxidation. This advice seems helpful until you realize that sometimes just washing the produce does not remove the pesticides, the harmful bacteria (when it’s an outbreak) or the wax layer from apples, lemons, oranges and bell peppers (meant to extend their shelf life). Washing apples days ahead removes their natural protective wax coating – yes, even organic apples have natural waxes. The same thing goes for apples: They release ethylene gas that causes other fruits and vegetables to ripen faster, so you’ll want to store them away from other produce to keep the apples from ruining the bunch. Picture this: you’re essentially removing their armor and then wondering why they brown faster than a banana in the sun. But, the best way to prevent your fruits and vegetables from oxidizing is to keep their insides away from oxygen in the first place. Keep them whole until just before you plan to cook or consume them. The moment you wash and cut an apple for next week’s lunches, you’ve started a race against time that the apple will lose.
Celery: The Wilting Warriors
Celery: Celery can be washed and chopped 3 to 4 days in advance. Store in a sealed bag or container with an airtight lid in the refrigerator. Sounds reasonable, right? Wrong. Vegetables that are best kept whole/uncut (due to rapid spoilage or color change): eggplant, tomatoes, white potatoes, cucumber and celery. Celery might seem sturdy, but it’s actually about 95% water held together by fiber and sheer determination. When you wash celery too early, you’re disrupting its delicate moisture balance. According to testing by Davison her ATK colleagues, the best way to store celery is to wrap it in foil first. The problem with early washing? You can’t wrap wet celery in foil without creating a humid nightmare that turns crisp stalks into limp disappointments. Excess moisture can also speed up food spoilage. Think of celery like a fresh haircut – it looks great initially, but every day after washing, it loses more of its original crunch and appeal.
Root Vegetables: The Underground Rebels
Root vegetables like carrots, sweet potatoes, beets and hard veggies like winter squashes and pumpkins are easily stored in partitioned containers. Wash first (I’m using ozonated water) to remove pathogens from their skin. Then peel if you want. This advice misses a crucial point about timing. The bigger the chunks the longer they keep fresh. Cut the green tops off, otherwise they will draw moisture from the root, and make them loose flavor and firmness. Root vegetables evolved to survive underground for months, but the moment you wash away their protective dirt layer and cut them, you’ve removed millions of years of evolutionary storage wisdom. Root vegetables like potatoes and carrots grow underground, but even above-ground produce like lettuce and tomatoes can be splattered with dirt and mud during the watering process. And anything that’s not organically grown can contain pesticide residue, so it’s really important to wash your produce before using it. But washing them a week before cooking is like taking off your coat in a blizzard – technically possible, but definitely not advisable for long-term survival.
Tomatoes: The Flavor Faders
Tomatoes (washed, whole). While this seems like basic prep advice, “This is especially true for tomatoes. “If they’re stored in the fridge the starches really become mealy,” explains Davison. Washing tomatoes too early strips away more than just surface dirt – it removes the invisible barrier that keeps them from becoming mealy disappointments. Vegetables that are best kept whole/uncut (due to rapid spoilage or color change): eggplant, tomatoes, white potatoes, cucumber and celery. Here’s what meal preppers don’t realize: tomatoes are basically water balloons with delicate skins. “The foods in this group are prone to “chill injury,” says Davison says, so it’s best keep them out of the fridge.” When you wash them days ahead and then refrigerate them, you’re essentially subjecting them to a one-two punch that destroys both their texture and flavor. It’s like washing your car and then immediately driving through a muddy construction zone.
Cucumbers: The Watery Washouts
Scrub firm produce, such as melons and cucumbers, with a clean produce brush. This FDA guidance makes cucumbers sound bulletproof, but they’re actually surprisingly delicate once washed. Vegetables that are best kept whole/uncut (due to rapid spoilage or color change): eggplant, tomatoes, white potatoes, cucumber and celery. Cucumbers are about 96% water, making them nature’s water bottles with edible packaging. This is true even for fruits and vegetables that have a rind you plan to peel like watermelon or cucumber. Otherwise, you could spread bacteria and other contaminants when you slice the fruit or vegetable. When you wash cucumbers too early for meal prep, you’re removing their natural waxy coating that prevents moisture loss. If you do have to wash them ahead of time, make sure they’re as dry as possible before storing them. Excess moisture can also speed up food spoilage. Think of it this way: unwashed cucumbers are like sealed water bottles, while washed ones become leaky containers that slowly deflate in your crisper drawer until they’re more suitable for composting than eating.
