Cross-Contamination in Commercial Kitchens

Food contamination poses a serious threat to food safety in a commercial kitchen. If food is contaminated, it is rendered unsafe to eat, as it could cause illness or injury to customers. Discussed in our overview of Food Safety and the Types of Contamination, there are three main types of contamination: physical, chemical and biological. The fourth type of contamination – cross-contamination – refers to the transfer of contaminants from a surface, object, or person to food. This type of contamination can also be biological, physical or chemical.

Types of Cross-Contamination

There are two types of cross-contamination: direct and indirect. 

Direct cross-contamination occurs when one food is directly contaminated through contact with another (also known as food-to-food contamination). The following are examples of direct cross-contamination:

• Raw poultry is stored above a salad in the refrigerator and the juices from the raw meat drip into the salad
• Unwashed produce contaminated with E. coli is stored in a bowl alongside washed produce
• Peanut oil splatters from a hot pan and a few drops land into a soup.

In these examples, the salad, the washed produce and the soup may be contaminated.

Indirect cross-contamination occurs when an object becomes contaminated and then passes the contaminants from one food to another. This type of contamination can be equipment-to-food or person-to-food and can occur if a surface or tool isn't cleaned and sanitized properly, or if foods are mishandled. The following are examples of indirect cross-contamination:

• A food handler finishes prepping a beef brisket and proceeds to cut up vegetables without washing their hands
• A mixing bowl used to make peanut butter cookies is immediately used (without being cleaned and sanitized) to make peanut-free chocolate chip cookies 
• The same cutting board is used to cut fish and vegetables

In each of these examples, the food was indirectly contaminated by bacteria or allergens that could harm a customer. Some of the most common sources of indirect cross-contamination in commercial kitchens include kitchen surfaces, utensils, and kitchen equipment, including small items such as cutting boards and mixing bowls. Equipment can also include cloths and towels, as well as clothing items like hairnets and uniforms. 

Another common source of indirect cross-contamination is insect infestation. Flies, rodents and cockroaches carry pathogens and disease-causing bacteria on their bodies, as well as in their saliva, droppings and urine. As such, pest prevention and control are critically important. 

How to Prevent Cross-Contamination

To prevent cross-contamination in your commercial kitchen, follow these guidelines:

• Flow through the kitchen in accordance with the Food Safety Plan 
• Always wash your hands or change gloves after working with potentially hazardous foods
• Properly store food in the refrigerator 
• Consider all raw and potentially hazardous foods as contaminated
• Use separate preparation areas for potentially hazardous foods (including high-risk foods like raw meat and seafood, as well as allergen-containing foods)
• Establish allergen management procedures 
• Prepare allergen-free meals separately from other meals
• Don’t use the same equipment or utensils for raw and cooked foods
• Clean and sanitize surfaces before switching food types
• Leverage our Guide to Pest Prevention and Control to find out more about the risks that pests pose to a food business, prevention of pests and actions to take if they get in

The best practices above are some of the ways you and your staff can prevent cross-contamination. Ensuring your staff have proper food safety training is another important step in preventing food contamination issues. For more information on our courses, visit our course page or contact us today.

Frequently Asked Questions

How often should kitchen staff receive training or refresher courses on preventing cross-contamination to ensure compliance with best practices?

In Canada, it's generally recommended that food businesses have at least one certified Food Handler on duty during all hours of operation. Food Handler certification typically needs to be renewed every five years.

Regular refresher training is encouraged to maintain high standards of food safety and to ensure that all employees are up to date with the latest practices and regulations​.

What specific cleaning agents are recommended for effectively sanitizing surfaces that have been in contact with raw meats to prevent cross-contamination?

To effectively clean and sanitize surfaces that have been in contact with raw meats and prevent cross-contamination, specific cleaning agents recommended include:

• Chlorine-based sanitizers: These are commonly used in food service environments. The concentration and temperature of the solution must be controlled according to the specific product's guidelines to ensure effectiveness.
• Quaternary ammonium compounds (quats): These are another popular choice for sanitizing food contact surfaces. They are effective at lower temperatures and are non-corrosive to surfaces but require proper dilution.
• Iodine sanitizers: Less common but still used, these sanitizers are effective at lower concentrations and have a broad spectrum of antimicrobial activity.

Each sanitizer must be used according to the manufacturer's instructions regarding dilution, temperature, and contact time to ensure maximum effectiveness.

Additionally, it’s crucial to ensure that any chemical residue is thoroughly rinsed off to prevent chemical contamination of food. Always follow Health Canada's regulations and guidelines for using chemical sanitizers in food premises to ensure compliance and safety.

Are there any technological solutions, like sensors or software, that can help monitor and manage cross-contamination risks in commercial kitchens?

Yes, there are several technological solutions available that can help monitor and manage cross-contamination risks in commercial kitchens:

• Smart Shelving and Inventory Systems: These systems utilize AI and IoT technology to monitor inventory levels and ensure proper handling and storage of food items, significantly reducing cross-contamination risks by automating restocking and tracking of inventory usage. This helps ensure that outdated or contaminated ingredients are not used inadvertently.
• Automated Sanitization Equipment: Technologies like UV light and steam-based sanitization are integrated into dishwashing and food storage equipment. These systems ensure high levels of hygiene by effectively killing pathogens without the need for chemical sanitizers, which reduces the risk of chemical contamination and enhances overall food safety.
• Touchless and Sensor-Based Technology: In response to hygiene requirements, sensor-based faucets and soap dispensers minimize physical contact in kitchen environments. This technology helps in reducing the spread of pathogens from person to person and surface to surface, thus lowering cross-contamination risks.

These technologies not only improve the efficiency of kitchen operations but also enhance food safety by systematically reducing the opportunities for cross-contamination.