Cheryl Luptowski, former home-safety expert and public information officer, NSF International (a global public health and safety organization), Ann Arbor, Michigan. NSF.org
You don’t want germs in your food, so of course you keep your kitchen clean…right? Maybe not! All of the cleaning in the world does little good if you miss the dirtiest spots because you don’t know where germs are most likely to lurk.
For example, when was the last time you gave much thought to your blender gasket? Or to the wooden block you use to store your knives? Probably ages ago, if ever, I’ll bet. Well, you should—and here’s why…
Microbiologists at NSF International, a global public health and safety organization, analyzed a wide variety of common kitchen tools and appliances for the presence of various microorganisms that can cause foodborne illness, including the bacteria Salmonella, Listeria and E. coli, as well as yeasts and molds.
In addition, the NSF team wanted to gauge public awareness of where such germs typically are found in kitchens. So they asked a panel of volunteers to say which kitchen items they thought were likely to be the most contaminated—and boy, were the volunteers off! For instance, they thought that the microwave keypad would be #1 and that the flatware storage tray would be #5…but neither of these items even made it onto the actual top 10 list of germiest items. What’s more, the true #1 germiest item—the refrigerator water dispenser—didn’t even appear in the volunteers’ top 10.
Here, the top 10 most contaminated areas, starting with the highest germ count…
1. Refrigerator water dispensers
2. Rubber spatulas
4. Refrigerator vegetable compartments
5. Refrigerator ice dispensers
6. Refrigerator meat compartments
7. Knife blocks
8. Rubber seals of food storage containers
9. Can openers
10. Refrigerator insulating seals
What makes these particular spots so germ-prone? When we posed this question to Cheryl Luptowski, a home-safety expert and consumer affairs officer at NSF International, she outlined several reasons…
Dark, damp environments are perfect breeding grounds for germs. When asked where germs thrive, people generally think of warm environments—but fully half of the top 10 contaminated areas were in the refrigerator. That’s because fridges offer moisture and darkness, which help germs take hold. Refrigerators also have lots of nooks and crannies where germs can hide. Luptowski said, “The volunteers guessed that the microwave keypad would harbor the most germs because people are always touching it. However, that keypad is exposed to the air, and it has a smooth surface where germs can’t take hold, and people tend to wipe it down a lot. In contrast, people tend not to clean the fridge that often…and when they do, they might just swipe at it with a damp cloth rather than really sanitizing it.”
Germs build up on items that aren’t often disassembled and cleaned. When is the last time you removed the head of your plastic spatula from its handle? Or scrubbed your can opener? Or took your blender apart—not just removing the jar from the motor unit, but really disassembling it all the way down to the blades and gasket? Do so now and you’re likely to find a disconcerting accumulation of crud (and the same probably goes for your food processor).
Utensils and small appliances often get put away before they are thoroughly dry. The moisture on the items plus the darkness inside the drawer or cabinet can encourage bacteria to breed. The same goes for the slots of a knife block—if the knives aren’t completely dry when they’re put away, bacteria can thrive in those damp, dark slots.
Kitchen pathogens aren’t just disgusting, they also can lead to serious health problems. Though anyone can fall prey, some people are at particular risk—for instance, those with compromised immune systems, including many of the elderly…pregnant women, for whom foodborne pathogens such as Listeria can increase the risk for miscarriage, preterm labor or stillbirth…and people allergic to yeasts or molds. That’s why it is so important to clean all your kitchen tools and appliances properly. Here’s what NSF International recommends…
Refrigerator water dispenser: Check your owner’s manual—according to NSF International, many manufacturers recommend the following method. Clean the dispenser’s waterspout weekly by dipping a small brush in distilled white vinegar and brushing the inside of the spout…then open the spout and allow it to run to clear away dirt and excess vinegar. Close the lever once there are no more traces of vinegar. Does this seem like overkill, given that we have all sorts of similar spouts in the house (i.e., every single faucet) that are never cleaned this way? When we asked Luptowski about this, she said, “It’s actually a good idea to clean all your drinking water faucets regularly to prevent the buildup of germs and bacteria. In one of NSF’s earlier germ studies, we discovered that the kitchen sink area tends to harbor a lot of bacteria, and thus both the sink and the kitchen faucet surface should be cleaned at least weekly with a sanitizing cleaner.”
Also, at least once a year, you should clean the refrigerator’s whole water dispensing system. To do that, turn off the water supply to the refrigerator and loosen the screw connecting the water line to the fridge. Once disconnected, pour four cups of distilled white vinegar into the tube (use a funnel). Wait 10 minutes, then reconnect the water line. Turn the dispenser on, allowing the vinegar to flow through the system and come out the dispenser’s waterspout. Continue until all the vinegar is gone and the water comes out clean. Don’t assume that having an inline water filter would solve the water dispenser germ problem, Luptowski cautioned. “Although filters can help reduce many different contaminants as well as water-treatment chemicals like chlorine, they don’t protect against bacteria or most other types of microorganisms,” she said.
Refrigerator ice dispenser: Turn off the ice maker. Empty the ice bin, and wash it with hot soapy water, then rinse and dry with a clean towel. Clean monthly. If you have just done your annual whole-system cleaning of the water dispenser, discard the first batch of ice to make sure there’s no vinegar in those first cubes.
Refrigerator meat and vegetable drawers: Once a month, remove drawers from the fridge, wash with hot soapy water and a clean cloth, rinse well and dry thoroughly with a clean towel. If your drawers are on top of each other, store the meats in the bottom drawer in case they leak. (Double-wrapping meats in plastic wrap or bags helps reduce that risk.) If meats do leak, clean the drawer immediately. With produce, to avoid cross-contamination, separate ready-to-eat produce from unwashed items.
Refrigerator insulating seal: At least monthly, wipe thoroughly with a damp, soapy dishcloth. Rinse the cloth well, wipe again, then dry with a clean towel. Be sure the seal is dry!
Blender: After each use, unplug the blender and remove the jar from the base. Completely disassemble the jar, separating the blade and gasket at the bottom from the main container and separating the lid handle from the rest of the lid. If components are dishwasher-safe (check your user’s guide), wash all pieces in the dishwasher (except the motor unit, of course). If hand-washing, use hot soapy water, rinse and dry before reassembling. Do the same for your food processor.
Can opener: After each use, wash handheld can openers in the dishwasher or hand-wash with hot, soapy water, then rinse well and dry. For electric openers, thoroughly wipe with a clean, damp, soapy dishcloth, paying special attention to the area around the cutting blades to be sure all food residue is removed…then rinse the cloth and wipe the can opener again. Dry with a clean dishtowel.
Rubber or plastic spatula: We all wash our spatulas, but what many of us fail to do is to separate the handles from the heads when the spatulas are made of two pieces—and bits of food (and germs) can accumulate in that joint. So for a two-piece spatula, separate the handle from the head and place both sections in the dishwasher. If hand-washing, separate the pieces and use hot soapy water, then rinse and dry thoroughly. With one-piece spatulas, if washing by hand, pay special attention to the area where the handle joins the head—there are sometimes crevices there.
Food storage container with rubber seal: This is likely to get clean enough when washed in the dishwasher—but sometimes people wash a container by hand (doing a less than thorough job) or even just rinse it and then reuse it. In that case, any food that has gotten trapped in the seal becomes a bacteria haven. So if you are hand-washing, use hot soapy water, giving extra attention to the seal and to the area where the cover attaches to the container. Rinse well, and allow to air dry completely.
Knife block: Most people probably never thoroughly clean this thing—but the NSF advises doing it monthly. First, turn the block upside down and shake…or use a can of compressed air to remove debris from slots. For nonwood blocks, hand-wash in hot soapy water, using a small brush (like a baby bottle nipple brush) to scour inside each knife slot, then rinse. To sanitize, mix one gallon of warm water with one tablespoon of bleach…then immerse the block in the bleach mixture or pour the mixture into each slot and wait one minute. Rinse thoroughly. Place the block upside down to dry, allowing air to get into the slots. Note: If you have a wooden block, this method could damage the wood—so check with the manufacturer for cleaning and sanitizing instructions. Easy alternative: Consider getting a magnetic knife rack, which doesn’t have any tough-to-clean slots. And however you store your knives, wash them in hot soapy water after each use, then dry completely before putting them away—to help keep germs at bay.