By Nuno F. Soares and Shuchi Arya
As food safety professionals, we are expected to apply and train others on basic principles of food safety. Among these are preventing cross-contamination, monitoring kill steps, cleaning, sanitizing, and a science-based approach to processes. Strangely, more often than we realize, we seem to leave all that food safety mindset at work and make basic mistakes when we use our own kitchens. If that is not your case, congratulations; but still, most of us fall short on what we can do to bring awareness to our family or community on the principles that should be implemented
when we prepare food and cook.
Some bad habits that people have in the kitchen passed through generations and may be simple to change. One typical example is washing raw meat under the sink faucet. Washing or rinsing of raw meat is not recommended because bacteria can cross-contaminate other foods, utensils, and surfaces. Droplets have been shown to disperse up to 50 cm in front of a sink and 60 to 70 cm to either side of a sink where chicken was washed (Everis & Betts, 2003).
In a study published in August 2019, “Food Safety Consumer Research Project: Meal Preparation Experiment Related to Poultry Washing” (RTI International for USDA, FSIS, OPACE, Food Safety Education Staff) a control group washed chicken 61 percent of the time. Meanwhile, participants who were informed that washing meat and poultry doesn’t destroy bacteria but spreads it, washed the chicken only 7 percent of the time.
Why the home kitchen?
Within a domestic environment, kitchens and bathrooms have high potential to function as “microbial incubators,” due to the continuous inoculation of new microbial cells, e.g., by food handling and direct body contact to domestic surfaces. The colonization success of these microbes then depends on the suitability of the environmental conditions, such as humidity and nutrient availability. Multiple use of the kitchen provides risky potential to introduce an array of pathogens which can contaminate foods, multiply, and result in illness.
Thus, the need to focus on one of our favorite areas at home: The kitchen.
Bacteria exist everywhere! They’re on you even now, and on the phone/tablet screen from which you’re probably reading this article. Pervasive as they are, these “invisible” microbial life forms are (usually) nothing to fear. You just need to fine-tune your kitchen food-handling practices and you can keep your food safe.
“Within one linear centimeter of your lower colon there lives and works more bacteria (about 100 billion) than all humans who have ever been born. Yet many people continue to assert that it is we who are in charge of the world.”
—Neil Degrasse Tyson
What do you think? Can you really eliminate most of the microbes in your house by only wiping down the counter surfaces, cutting boards, appliances, and utensils with your soapy sponge and/or through the dishwasher? The answer, unfortunately, is no.
Key pathogens found on frequently touched areas of the home kitchen
(Adapted from Redmond and Griffith, et. al.)
Sites or objects commonly contaminated in the home kitchen
Bacteria are attracted to warm, moist environments, which is why the kitchen is one of the germiest rooms in the house. A 2011 study by NSF International categorized the household objects with the highest germ count. They found sponges and dish rags were the dirtiest household items, followed by kitchen sinks, toothbrush holders, pet bowls, coffee reservoirs, faucet handles, countertops, stove knobs, and cutting boards.
Contrary to what people may think, the bathroom is not the dirtiest place in the house! The study found more Coliform bacteria (an indicator of potential fecal contamination) in the kitchen rather than the bathroom. In fact, Coliform was found in 75 percent of dish sponges/rags, 45 percent of kitchen sinks, 32 percent of countertops, and 18 percent of cutting boards.
Commonly contaminated kitchen items include:
- Sponges. Dr. Chuck Gerba, a professor of microbiology at the University of Arizona, who studies how diseases are transferred through the environment, agrees that the kitchen sponge or cloth is almost always the dirtiest thing in your house. His studies have shown that, compared with the average toilet seat, where there are about 50 bacteria per square inch (~6.5 square cm), there are about 10 million bacteria per square inch on a sponge, and a million on a dishcloth. If you are someone who repeatedly uses the same sponge to wipe your kitchen counters, dishes, and table, replacing it every month or so, a study published in Scientific Reports on July 19, 2017 concludes that these sponges have massive colonization by Acinetobacter, Moraxella, and Chryseobacterium species. Kitchen sponges, due to their porous nature and water-soaking capacity, represent ideal incubators for microorganisms (evident under the microscope).
- Towels. There are more bacteria on towels, as they are used for multiple purposes like drying hands, wiping utensils, wiping surfaces, etc. Notice that it is more common than you might think for people to use the same towel to wipe spills and then use it to dry just-cleaned plates before laundering it! A better way is to have paper towels for cleaning the countertops and use dedicated towels to dry cleaned utensils, or air-dry cleaned utensils on a dish rack.
- Kitchen faucets. When was the last time you cleaned your kitchen faucet? The common metal aeration screen at the end of the kitchen faucet has a noble purpose for the environment, but can be a spot for bacteria growth, which can even develop into harmful biofilms that stick to the screen.
- Stove knobs. Although not a place that many of us think about, stove knobs are in the top ten for common places for germs to hide. We do clean our stove tops but pay less attention to the stove knobs. As a food safety professional, we should note that our hands constantly touch the stove knobs—but do we ever think of cleaning these stove knobs? As per the National Sanitation Foundation, stove knobs should be cleaned once per week (remove knobs, wash in hot soapy water, rinse well, let dry, and re-install).
- Drainage pipes. Removing household wastewater is an important environmental health intervention for reducing disease. Poorly drained wastewater forms stagnant pools that provide breeding sites for disease vectors. Because of this, some diseases are more common in the wet season than the dry season. Drain cleaning and use of suitable disinfectants are important building maintenance steps.
Potential hazards and control measures
If we put on our food safety professional glasses to look into our kitchen you will notice, like in any other step of the food chain, we will identify potential sources of biological hazards (e.g., Salmonella and Campylobacter in raw meat and poultry), chemical hazards (e.g., cleaning chemicals, lubricating oil from mixer grinders), and physical hazards (e.g., broken glass, rubber bands, brittle plastic, wire ties, staples from grocery bags, etc.).
Cross-contamination of food occurs when bacteria or other potentially harmful microorganism are unintentionally transferred from one place to another, i.e., from one food item to another. There are three ways of cross-contamination in the kitchen:
- Food-to-food, e.g., raw meat touches cooked meat in storage
- People-to-food, e.g., food handler handles raw meat and then touches cooked meat with the same hands without proper hand washing
- Equipment-to-food, e.g., food handler uses the same chopping board first to chop raw meat and then to chop ready-to-eat fresh salad vegetables; the USFDA recommends replacing worn cutting boards as they wear out over time because indentations caused by knives cutting into the board are harborage sites for pathogens
You should also assure that incoming products are safe, not only the more obvious like raw meat, fish, produce, or eggs but also of the water used to cook, clean, make ice, and rehydrate foods, for example. Additional content regarding proper storage and cooking time-temperature control is available in the Appendix.
Back in 2006, the WHO published Five Keys to Safer Food, a manual that recognized the need to educate food handlers about their responsibilities for food safety. The introduction of Good Consumer Practices has been advocated by Sean Leighton, M.Sc., M.B.A., and William H. Sperber, Ph.D., as a recognition that consumers should be responsible for the safe handling of their food and making real food safety from farm-to-fork.
Food safety professionals are special consumer advocates. We have a higher responsibility, because we know better, and we not only have to walk the talk but also to educate our families and everyone else we can.
We would like to challenge you to take action! Who could you help bring awareness to this issue and teach one simple thing she/he could do differently to manage hazards in the kitchen? Please add your comments relating what you will do today to make food safer at home.
Special thanks to Jocelyn Lee Lion for contributing to and editing this article.
Storage Upon Receiving:
1. Place potentially hazardous foods in the proper storage area quickly to avoid bacterial growth:
- 41ºF or lower—refrigerator temperatures
- 26ºF to 32ºF—deep chill storage temperatures
- 0ºF or below—freezer temperatures
- 50ºF to 70ºF at 50% to 60% humidity—dry storage temperatures
2. Place foods into appropriate storage areas immediately upon receipt in the following order:
- Refrigerated foods—if food products are stored together in a refrigerator, they should be placed on shelves in the following order:
- Frozen food
- Dry goods
3. Store food out of direct sunlight.
4. Place chemicals and supplies in appropriate storage areas, away from food.
5. Rotate goods when placing them in storage by placing the new items behind the old items to ensure that the older items are used first (First In, First Out inventory rotation).
6. Store food in original container if the container is clean, dry, and intact. If necessary, repackage food in clean, well-labeled, airtight containers. This also can be done after a package is opened. Food is NEVER put in chemical containers and chemicals are NEVER placed in food storage containers.
7. Store potentially hazardous foods no more than seven days at 41ºF from date of preparation, which counts as “day 1.”
8. Store pesticides and chemicals away from food handling and storage areas. They must be stored in original, labeled containers.
General Process Practices-Time and Temperature Relationships
(adapted from 2017 California Retail Food Code Article 2)
About the authors
Nuno F. Soares, Ph.D. is the founder of The Why of Food Safety—Become the SLO initiative and author of several books and articles on food safety, namely FSSC 22000 V5 and ISO 22000:2018 Blueprint and Food Safety in the Seafood Industry (Wiley). He is an author, consultant, and trainer in food safety with more than 20 years background in the food industry as a food safety/quality and plant manager. You can reach him at www.nunofsoares.com.
Shuchi Arya is food safety expert and author. She is a trainer, committee member, and accreditation expert with more than 12 years background in food industry and certification bodies.