The kitchen sink is a common place for mold to grow, especially in damp areas where food bits and water tend to gather. Discover the other hidden spots where mold thrives and use these expert tips to keep your kitchen safe.
Photograph AJ_Watt, Getty Images
From dishwashers to fridge gaskets, mold can hide in plain sight. Discover practical tips to keep your kitchen clean and mold-free.
Mold is pretty much everywhere. A hugely diverse category of fungi, molds reproduce by releasing clouds of microscopic spores—seed-like particles that can land and thrive almost anywhere with water, food, and oxygen.
Kitchens, unsurprisingly, are a reliable source for all of those needs. If you’ve ever noticed a bit of black lining the rim of your blender or the back corner of your fridge, you’re not alone. Thanks to damp conditions and a steady influx of food, kitchen mold is an inevitable part of life.
While these small amounts are not likely to have health impacts, some mold can induce allergic reactions or, in extreme cases, produce acute toxic effects. But proper kitchen hygiene will stave off the worst mold mishaps. Experts offer tips for finding, removing, and avoiding the fungus altogether.
Where does mold lurk in our kitchens?
Like other microbes, molds aren’t too picky about where they grow.
“Theoretically, there are really no surfaces that microbes [like mold] won’t grow on,” says Jordan Peccia, a professor and chair of the chemical and environmental engineering department at Yale University. He says, from plastic to wood to steel, “if there’s some water there, they’ll find a way.”
Still, certain spots are particularly ripe for fungal growth. Peccia points to parts of the kitchen that are regularly wet but not always used or cleaned—like coffee machines. “If you have a coffee maker and you run it but you don’t clean it out every day…mold will grow right on top of that,” he says. “Same thing about a blender seal…anything that’s just constantly wet.”
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Refrigerators provide particularly fertile ground for mold, according to Don Schaffner, chair of the food science department at Rutgers University. “The fridge gasket is a good one because it can accumulate moisture,” he says. Other hotspots include the fresh produce drawer or that back corner where condiments might’ve leaked out. A 2014 study found significant growth of mold and other microorganisms in refrigerators, particularly on the bottom shelf.
Food is the biggest source of mold in the kitchen. While products like fresh fruit, soft cheese, and loaves of bread are ideal ground for mold growth, even microscopic amounts of food—think coffee spills, residue from leaky jam jars—can sustain colonies.
(What do you do when you see mold on your food?)
“Any place in your kitchen that can get food stuck in it and then can either acquire moisture from the air or from the food—any of those kinds of places could accumulate mold,” Schaffner says.
Other kitchen appliances also support mold growth. “There are a lot of fungi that live in our dishwashers,” says Joan Bennett, a plant biology and pathology professor at Rutgers University. Research has shown that a whole host of mold (and other fungal) species can colonize dishwashers despite the extremely high temperatures and moisture.
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It’s not just the solid surfaces that are prone to mold growth—dish towels and floor mats are also prone to mold. Part of the danger is that mold in floor mats might be hard to spot, unlike on a white wall or plastic shelf. Similarly, dish towels, if used frequently and left sitting out damp, will happily grow colonies of mold, yeast, and bacteria.
Though Schaffner has never seen visible mold on sponges—which, like cutting boards and sink handles, are highly trafficked and ripe for bacteria—that doesn’t mean mold can’t also grow there. “Sponges hold water; sponges can hold food debris,” he says. “We know, based on published research, that probably one of the dirtiest places in the kitchen is the kitchen sponge.”
How to avoid—and treat—kitchen mold
Most mold growth is avoidable simply by keeping a clean, dry kitchen.
“The key thing is to keep the humidity low,” Peccia says, adding that, as a rule, “mold will not grow on a dry surface.” Watch out for condensation, wipe up spills and leaks, and clear surfaces of dust and debris. He recommends dehumidifiers and air conditioning for homes in particularly damp environments.
While there’s no hard and fast recommendation for how often to clean the fridge and other kitchen surfaces, Schaffner suggests somewhere between weekly and biweekly is generally appropriate.
As for towels and sponges, the most important thing is to reduce moisture accumulation and change them frequently. “Let your sponges dry out,” Schaffner says. “If they’re sitting in the bottom of the sink in a little bit of water, I’ll rinse them, squeeze them out, [then] I’ll set them in the dish drain in a place where they can dry.” Want to do a quick sponge sanitization? Schaffner advises throwing them in the dishwasher or microwaving them in a bowl of water.
Still, leaks and spills can go unnoticed, and the occasional mold colony is inevitable. So, what happens when you notice a suspicious-looking patch?
As a general rule, food safety experts recommend tossing moist foods—such as brie, yogurt, hummus, and berries—when mold appears. Denser, drier foods like hard cheese or carrots, can be safely salvaged after cutting off the mold, plus an extra inch or so.
(Behold the surreal magic and mystery of slime molds.)
When it comes to moldy surfaces like countertops and refrigerator shelves, Schaffner says to wash them with soap and water before disinfecting them with bleach. “Bleach is a tremendously effective sanitizer,” he says, emphasizing that you must first wash away the macro and microparticles. “You can’t sanitize a dirty surface.”
But removing the mold is only half the battle. Where there’s mold, there’s moisture; where there’s moisture, there’s bound to be more mold. As Peccia says: “You’re fixing the symptom but not taking care of the real problem.” He recommends identifying the source of the mold—a water leak, rotting food, a broken fridge seal—and trying to fix it.
Mold isn’t usually a problem unless it persists, Schaffner says. Though some molds release toxic compounds called mycotoxins, others are completely harmless. And small amounts of mold generally aren’t cause for alarm.
“Molds are part of the normal aerosol,” says Bennett. “Our air is full of microbes, and our surfaces are full of microbes.” Sometimes, with all the emphasis on eradicating microbes, she adds, “we forget that an awful lot of microbial life is normal and good.”
