In the fast-paced world of food service, cross-contamination is a silent yet serious threat that can jeopardize both the safety of your customers and the reputation of your business. With a few focused strategies, cross-contamination can be effectively prevented, keeping both food safety and customer trust intact.
Here’s a breakdown of the common causes of cross-contamination that every food service operation should watch out for, from an expert’s point of view:
1. Dirty Produce and Improper Washing of Fruits and Vegetables
One often overlooked cause of cross-contamination is not properly washing fruits and vegetables before preparing them. Produce can carry dirt, pesticides, and bacteria from the farm, and if it’s not properly cleaned, those contaminants can end up on food that’s ready to be served. This is especially concerning when prepping raw salads, herbs, or garnishes.
Expert Advice: The old adage, “If you want something done right, you have to do it yourself” applies here too - even though an item is labelled “triple washed” doesn’t mean it’s completely clean. Always wash fruits and vegetables under running water—even those with skins you don’t eat, like melons. For leafy greens, separate leaves and rinse thoroughly. If necessary, use a food-safe wash to ensure produce is thoroughly cleaned.
2. Shared Equipment and Utensils
In a busy kitchen, it’s easy to fall into the trap of using the same cutting board or knife for multiple tasks. But that’s a recipe for disaster (no pun intended). Using one tool for both raw and cooked foods without cleaning it in between can spread harmful bacteria—quickly and quietly.
Expert Advice: Designate specific tools for raw and cooked foods and always sanitize between uses. Color-coded cutting boards and knives are a simple and effective way to minimize risk. FoodDocs offers a cheat sheet for color coordination that will keep your kitchen safe and in sync with industry standards.
3. Surfaces that Aren’t Clean Enough
It’s not just about wiping down counters—it’s about thoroughly sanitizing them. A cloth that’s been used to wipe down raw meat juices shouldn’t be used to clean surfaces where fresh veggies are being prepped. Even a small amount of residual bacteria can contaminate large batches of food.
Expert Advice: Implement a strict cleaning schedule and ensure all surfaces are cleaned and sanitized using food-safe chemicals.
4. Improper Food Storage
One mistake we’ve seen too often is storing raw meat on the top shelf of a fridge. When juices drip, it’s not just the raw chicken that’s at risk—it’s everything below it. This could easily contaminate ready-to-eat foods, leading to potentially dangerous outbreaks.
Expert Advice: Raw meats should always be stored on the bottom shelf, in leak-proof containers, to prevent drips from contaminating other foods.
5. Handling by Ill or Injured Employees
I know it’s a tough one—getting workers to take sick days—but it’s critical. Even the slightest illness or an open wound can be a source of contamination. Ensure your team understands the importance of staying home when they're unwell and following proper protocols if they have cuts or rashes. These days, masks and gloves are commonplace, but some illnesses can’t be contained.
Expert Advice: Have a clear policy in place that encourages staff to report symptoms early, and provide training on the importance of wearing gloves if handling food with a wound.
6. Poorly Maintained Cleaning Supplies
This may seem like a minor issue, but dirty towels or sponges can easily spread bacteria across multiple surfaces. It’s important to regularly clean or replace them to avoid transferring harmful germs.
Expert Advice: Use disposable towels for cleaning and sanitize sponges and cleaning cloths at the end of each day.
7. Under-Cooked Foods
While it may be tempting to speed things up, under-cooking proteins, particularly poultry and ground meats, is a serious cross-contamination risk. Bacteria like Salmonella and E. coli can survive if food isn’t cooked to the correct temperature.
Expert Advice: Invest in food thermometers & timers, educating staff on the safe cooking procedures for all types of food. Consistency here is key.
8. Inadequate Hand Hygiene
You’d be surprised at how often this one is overlooked. As industry professionals, we can’t stress enough the importance of proper handwashing. Raw foods—especially meats—harbor bacteria that can easily transfer to ready-to-eat items if hands aren't washed properly. It sounds basic, but this is the number one cause of foodborne illness outbreaks in food service.
Expert Advice: Encourage staff to wash their hands frequently and train them on the proper technique: 20 seconds with soap and water, and don’t forget the wrists and under the nails. Some municipalities require handwashing signs be posted in kitchens & restrooms.
Types of Cross-Contamination
There are three broad types of contaminants:
1. Biological contamination
When harmful microorganisms, or pathogens, are consumed, biological contamination can occur. There are four types of pathogens that can contaminate food and cause foodborne illness: bacteria, viruses, parasites, and fungi (mold and yeast). The FDA reports more than 40 kinds that can occur in food and cause illness. These pathogens are each commonly found in certain places. The big 4 – dubbed because they are highly contagious and can cause severe illness – include:
- Bacteria
Bacteria requires six conditions to grow: food, acidity, temperature, time, oxygen and moisture (FATTOM). To prevent bacteria growth, the best course of action is to control time and temperature, always doing your best to ensure that food mandating time and temperature control is kept out of the temperature danger zone (between 41°F and 135°F).
Types of bacteria & where they are commonly found: Salmonella (raw poultry, eggs & meat), E.coli (undercooked ground beef, unpasteurized milk & contaminated water), Listeria (deli meats, unpasteurized cheese, grab & go foods) & Campylobacter (raw or undercooked poultry & unpasteurized milk). - Viruses
Viruses need a living host to survive, thus why they are carried and transmitted by humans and animals. People can contract a virus from food, water or contaminated surfaces. Unlike bacteria and parasite, viruses cannot be destroyed by cooking food to minimum internal temperatures. The best way to prevent a virus is by practicing good personal hygiene and mandating staff stay home when they’re ill.
Types of bacteria & where they are commonly found: Norovirus (shellfish, salads, food handled by infected workers) & Hepatitis A (contaminated food or water). - Parasite
Parasites are commonly associated with seafood, wild game, and food processed with contaminated water, like produce. They require a host to thrive. To prevent, always ensure your food products are purchased from an approved, reputable supplier and that cooked food meet the required minimum internal temperatures.
Types of bacteria: Protozoa/Giardia, Helminths & Roundworms. - Fungi
Molds are tiny fungi that grow on plant or animal matter. There are tens of thousands, possibly up to 300,000 species. Most molds are threadlike and produce spores, which can spread through air, water, or insects. Unlike bacteria, which are single-celled, molds are made up of many cells and can sometimes be seen with the naked eye. Under a microscope, they look like small mushrooms. Molds have three main parts: root threads that grow into the food, a stalk that rises above the food, and spores at the top of the stalk. The spores give mold its color and spread to new areas. Molds also have thin, thread-like roots that may be deep inside the food and can be hard to see. Along with the mold, invisible bacteria may also be present. The USDA has a food safety information card to help kitchen staff understand the dangers of mold on food.
2. Chemical Contamination
If not correctly utilized, everyday chemicals like cleaners, sanitizers, and polishers can contaminate food and cause illness. Ensure that chemicals are approved for use in a foodservice operation and purchased from approved suppliers. Store away from prep areas, food storage areas and service areas, and separate from food and food-contact surfaces with proper spacing and partitions. Never store chemicals above food or food-contact surfaces, and always use only for their intended use, following the manufacturer’s directions. Also, be sure to handle food only with equipment and utensils approved for foodservice. All chemicals should be clearly labeled.
3. Physical Contamination
Occurs when physical objects find their way into foods. These could include dirt, hair, bandages, metal shavings, glass, jewelry, etc. Natural objects, such as fish bones, are also considered physical contaminants, which could cause mild to fatal injuries such as cuts, dental damage, and choking. More seriously, and often leading to necessary kitchen closures, is the presence of filth, including dirt, feces, insect parts, etc. To help prevent, carefully inspect all food you receive and take steps to make sure food handlers are aware of their surroundings. Jewelry should be removed, and hair nets donned before handling food.
Conclusion
Preventing cross-contamination isn’t just about following guidelines—it’s about creating a culture of food safety in your establishment. From our decades serving commercial kitchens, we can say that the businesses that thrive are the ones that prioritize these practices, educate their staff regularly, and never let their guard down.
In an industry where a single mistake can result in serious consequences, it’s always better to be proactive. The safety of your customers—and the integrity of your operation—depends on it.
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