Clean the Germiest Kitchen Items

Scientists at NSF who are involved in testing kitchen products for NSF's Home Products Certification Program wondered whether consumers are actually following manufacturer cleaning instructions for many home appliances and kitchen products (NSF verifies manufacturer cleaning instructions among other criteria before home products that can bear the NSF mark).

When conducting the 2013 NSF Germ Study, NSF's microbiology team analyzed several kitchen appliances and tools for the presence of foodborne pathogens. The study revealed that many common kitchen appliances and tools used to store and prepare food can harbor pathogens that cause foodborne illness when they are not cleaned properly.

Below is a list of items where germs were discovered in this latest study, along with steps you can take to help keep your kitchen clean.

In this year’s study, NSF scientists found refrigerator vegetable compartments to be one of the germiest places in test homes. Germs found included Salmonella and Listeria as well as yeast and mold.

To effectively clean the vegetable compartment, first remove the drawer from the refrigerator if possible. Use a clean sponge or soft cloth and wash the bin with a mild detergent mixed with warm water. Rinse with tap water and wipe dry with a clean towel. To help control odors, use warm water mixed with a baking soda solution (about 1-2 tablespoons of baking soda to 1 quart of water). Rinse and wipe dry. Clean monthly.

Always store produce separately. To avoid cross-contamination, separate ready-to-eat and unwashed produce. Separate all produce from other foods such as raw meat, poultry and seafood. In the refrigerator, produce should always be stored on a separate shelf above meat, poultry and seafood to avoid raw juices dripping onto the produce. Keep them separate in your grocery cart, during food preparation and when using kitchen tools and appliances as well.

Perhaps not surprisingly, refrigerator meat compartments were also found to be one of the top hiding places for germs. In addition to yeast and mold, both Salmonella and E. coli were found.

To effectively clean, remove the compartment/drawer from the refrigerator if possible. Use a clean sponge or soft cloth and wash the bin with a mild detergent mixed with warm water. Rinse with tap water and wipe dry with a clean towel. To help control odors, use warm water mixed with a baking soda solution (about 1-2 tablespoons of baking soda to 1 quart of water). Rinse and wipe dry. Clean monthly and whenever you see any spilled meat juices. In the refrigerator, store meat and seafood on a separate shelf below produce to avoid raw juices dripping onto the produce.

Although many volunteers didn’t consider blenders to be a germy item, in reality they were the third germiest item in this year’s test homes. Salmonella, E. coli, yeast and mold were all found on blender gaskets.

To clean, unplug the blender and remove the blender jar from the base. Completely disassemble the jar, removing the blade and gasket at the bottom. If dishwasher safe, place all pieces in the dishwasher after each use. If hand washing, wash the gasket, blade assembly, jar and lid thoroughly in hot soapy water, rinse and dry before re-assembling. Perform this cleaning procedure after each use.

While many volunteers recognized that can openers could harbor germs, the NSF germ study found that these items were not being cleaned effectively, as traces of Salmonella, E. coli, yeast and mold were all detected.

To effectively clean, place the can opener in the dishwasher after each use (if dishwasher safe). If hand washing, wash the can opener in hot soapy water, rinsing thoroughly with clean tap water before air drying after each use. If hand washing, pay special attention to the area around the cutting blades to be sure all food residue is removed.

Similar to can openers, most volunteers identified rubber spatulas as one of the top 10 places for germs to potentially hide. But NSF’s scientists discovered that these items were not being properly cleaned either, as E. coli, yeast and mold were all found.

To clean, for two-piece spatulas it’s important to separate the handle from the spatula portion and, if dishwasher safe, place both sections in the dishwasher after each use. If hand washing, wash in hot soapy water, rinsing thoroughly with clean water. For one-piece spatulas, if dishwasher safe, place in the dishwasher after each use. Otherwise, hand wash thoroughly in hot soapy water, paying special attention to the area where the handle joins the spatula. Rinse thoroughly and dry.

While food storage containers also never made our volunteers’ top 10 list, tests revealed they were the eighth germiest place in the kitchen. Salmonella, yeast and mold were all detected.

If dishwasher safe, place both the container and the lid in the dishwasher and wash after each use. If hand washing, wash both the container and lid in hot soapy water, paying special attention to the area around the seal as well as any grooves where the cover attaches to the container. Rinse thoroughly and allow to air dry.

While the refrigerator water dispenser didn’t make our volunteers’ top 10 list of germiest places, the dispenser proved to be a concern for both yeast and mold, which can be a significant problem for individuals with allergies.

Check your refrigerator manual for cleaning instructions. Many companies recommend using a solution of vinegar and water to clean the dispenser and ice maker. First turn off the water supply to the refrigerator and then loosen the screw connecting the water supply line to the refrigerator. Once disconnected, use a small funnel to pour 3-4 cups of distilled white vinegar into the tube. Wait five to 10 minutes and then reconnect the water line. Turn the dispenser on to allow the vinegar solution to flow through the dispenser’s system and spill out through the waterspout. To clean the waterspout, use a bottle or baby bottle nipple brush dipped in distilled white vinegar. Brush the inner side of the spout, then open the waterspout and allow it to run to clear of any dirt and excess vinegar solution. Close the lever when there are no traces of vinegar. Clean the waterspout weekly and the refrigerator water dispenser system once or twice a year.

Similar to refrigerator water dispensers, refrigerator ice dispensers were also found to be contaminated with yeast and mold

To clean, turn the ice maker off, empty the ice from the ice bin and wash the bin with mild dish soap and warm water using a sponge or soft cloth. Wipe dry with a clean towel. If also cleaning the refrigerator’s water dispensing system with vinegar, be sure to throw away the first batch of ice, since it still might taste sour from the vinegar solution. Clean monthly.

Dark moist environments can be a breeding ground for germs, and knife blocks proved to be no exception. Both yeast and mold were found in the knife blocks present in this year’s test homes.

To clean, first remove any knives stored in the block. Turn the knife block upside down and shake lightly or use a can of compressed air to remove crumbs and other loose debris. Hand wash the knife block in hot soapy water, using a small brush (like a baby bottle nipple brush) to scrub out the knife slots. Rinse thoroughly with clean water. To sanitize, prepare a bleach solution of 5 tablespoons (1/3 cup) bleach per gallon of water or 4 teaspoons bleach per quart of water. Either immerse the complete block in the water/bleach mixture or fill the knife slots. Allow the bleach solution to sit in contact with the slots for one minute. Rinse the block and knife slots thoroughly with clean tap water and place the block upside down on a clean surface to air dry. To avoid mold and bacterial buildup, wash knives thoroughly after each use and let them dry completely before placing them in the knife block. Wash and sanitize the knife block monthly if used frequently.

NSF’s 2013 germ study found germs on many everyday kitchen appliances and tools that come in direct contact with food, especially raw produce, meat, poultry, seafood and ready-to-eat items. While many germ study volunteers correctly identified items that they thought would harbor the most germs, the study revealed they are not always cleaning them sufficiently to prevent illness. These findings are most concerning for households with at-risk populations such as children, pregnant women, the elderly or those with a compromised immune system (from illness).

The lesson we can all learn as consumers is to follow manufacturer’s directions when it comes to cleaning and sanitizing kitchen tools and appliances.