Cross-contamination presents a serious health and safety risk in kitchen environments. Once something has been contaminated it is often very difficult to identify where this contamination has come from and any other products or items that have been contaminated, so preventing it where possible should be a priority.
There are a variety of vehicles for cross-contamination which are important to know if you’re going to be working in a kitchen or food production environment, and many pieces of health and safety guidelines are linked to reducing the risk that these vehicles pose. In this article, we identify some of the most common cross-contamination vehicles, along with sharing the best ways to prevent cross-contamination.
Cross-contamination is the process in which a biological, physical, allergenic or chemical contaminant moves from one place to another and comes in contact with a food product as part of this journey. It can happen from food product to product, from an object to a food product, or from a person to a food product.
The risk that cross-contamination presents can be very serious, as ingesting a harmful substance can sometimes lead to major health issues. All kitchen environments are places where cross-contamination is a risk, but businesses manufacturing, serving and storing food need to be particularly careful as they can face legal consequences if a customer is harmed because of cross-contamination.
Cross-contamination can be relatively easy to prevent if you know how it commonly occurs, the key vehicles for cross-contamination and the best ways to stop it from happening. There’s plenty of guidance out there, including legal requirements for how to stop cross contamination which has been dictated by the Food Standards Agency.
Cross-contamination can happen in a variety of different ways in many different scenarios. The types of cross-contamination in food can be loosely divided into four categories, which we will explain below.
Chemical contamination involves either natural or artificial chemical substances coming into contact with a food product and contaminating them. For example, a cleaning product being used in the food preparation environment might accidentally come into contact with a product as it is being manufactured, or pesticides used in a farming environment might contaminate an ingredient before it was harvested.
Biological contamination is one of the most common forms of cross-contamination and occurs when a food product gets contaminated by an organism like bacteria or another kind of germ. It also refers to food becoming contaminated by a substance produced by another food product.
Physical contamination is what happens when a food product gets contaminated by a foreign object. This usually involves something from the environment during the production process getting mixed up in the product ingredients, such as plastic packaging or a piece of jewellery from someone handling the ingredients.
Allergenic contamination refers to what happens when an ingredient that is classed as an allergen contaminates a food product that is not supposed to have that ingredient in it. This can happen directly through getting added to the product or indirectly such as storing a product in a container that previously held an allergen. Allergenic contamination can be very dangerous as someone with an allergy to that ingredient might accidentally be exposed without realising it.
Cross-contamination vehicles are the objects or interactions that facilitate the biological, chemical, physical or allergenic contamination of food products. By understanding what the most common vehicles are and why they pose a risk, you can better understand the best ways to prevent cross-contamination.
In a kitchen, the surfaces that are used to prepare food are some of the biggest vehicles for cross-contamination. Biological, allergenic and chemical contaminants are often transferred onto these surfaces, and if they aren't cleaned properly before more food is prepared then it’s very easy for ingredients to get contaminated.
Food preparation surfaces are also key vehicles for some physical contaminants, as small or non-edible items might be left lying around in a messy kitchen space and accidentally get mixed up with ingredients.
The best way to reduce the risk of cross-contamination from food preparation surfaces is to make sure that these surfaces are regularly cleaned, especially after any raw ingredients are handled on them. Remove any debris and then use an antibacterial cleaner to wipe down surfaces and get rid of any germs that might be lingering there.
Chopping boards are another key vehicle for cross-contamination between food products, particularly if you’ve been using them to prepare raw meat and fish. If you use the same board for multiple ingredients, there’s a high chance that a contaminant might pass from a contaminated product to the board and then the board back to a different ingredient, contaminating this as well.
When you’re busy in a kitchen, it can be tempting to just use the same equipment, like chopping boards, over and over, especially if they don’t appear to be dirty. However, one of the best ways of preventing cross-contamination is to use a new chopping board for every food product, helping to keep any potential contaminants contained.
After use, chopping boards should always be cleaned and disinfected before they are used again. Many food establishments also use different coloured chopping boards for different ingredients, such as raw meat, raw fish, cooked meat, raw fruit and veg and other products, which helps to reduce the risk of cross-contamination even further by keeping ingredients separate.
Similarly to chopping boards, utensils are a common vehicle for the contamination of food when contaminants are transferred from one ingredient to another by items like knives, spoons or tongs. Again, it’s much easier to just use the same utensil for multiple tasks if it looks clean, but this isn’t a good idea in a working kitchen as it’s very easy to contaminate multiple food products in this way.
All utensils should be washed between uses using hot water and antibacterial soap to remove any contaminants from them. It can also be a good idea to designate specific utensils for use with potentially hazardous ingredients like raw meat, fish, dairy and egg products, which reduces the likelihood of cross-contamination even further.
Cloths tend to be used in a kitchen to clean the area, but they can actually be a vehicle for cross-contamination. If a cloth is used to clean up a harmful substance and then used again to clean a surface, there's the potential for this substance to be transferred to the surface and then a food product if the two come into contact.
It can be tricky to remember, but new cloths should be used for every new cleaning job, or at least properly disinfected between uses. You can do this by soaking the cloth in hot water and a cleaning product, or by putting it through the washing machine.
You should also always remember to wash your hands after using a cloth for cleaning, as it’s also possible for cross-contamination to occur if harmful substances transfer from the cloth to your hands and then to a food product.
Finally, hands are one of the biggest vehicles for cross-contamination. All kinds of potentially hazardous contaminants can be transferred to your hands to food products, often without being visible, and your hands can quickly contaminate multiple touchpoints in a kitchen which can then lead to high levels of cross-contamination.
The best way to avoid cross-contamination of foods from your hands is to make sure to wash your hands regularly when working in a food preparation area, especially after touching raw ingredients or cleaning surfaces and equipment. Hands should be washed with hot water and soap for at least 20 seconds and dried on a clean cloth or paper towel before touching anything else.
We’ve already touched upon some of the best ways to prevent cross-contamination in the sections above, but there are additional ways in which you can reduce the risk.
The first is that you should keep all ingredients separate whilst you are storing them in fridges, freezers or in cupboards. This helps to prevent cross-contamination between food products, especially when you follow the official advice on the best way to store different kinds of food.
Secondly, it can be worth putting an official system in place in a working environment that helps to reduce the risk of cross-contamination by designating specific areas and equipment for different tasks. This might involve isolating raw food handling to a particular part of the kitchen, only using a certain colour of equipment for specific ingredients or cleaning products, and even having certain members of staff only handle particular products or equipment throughout their shift.
Finally, one of the best ways to prevent cross-contamination is to ensure that everyone involved has been given appropriate health and safety training. By properly understanding the risks and the measures put in place to reduce or remove these, employees will be aware of what they should avoid and understand the need to follow systems and processes designed to reduce the chances of cross-contamination.
Bacterial contamination is the biggest cause of cross-contamination in food, usually by harmful bacteria from food products getting transferred onto other ingredients. This can happen directly between products if they’re stored incorrectly, or may happen if a surface, utensil or piece of equipment isn’t cleaned properly.
The most effective way to prevent cross-contamination is to keep food preparation and serving environments clean. This helps to massively reduce the chances of all kinds of contamination by preventing the transfer of germs or chemicals and keeping the area clear and free from many physical contaminants.
Food poisoning is caused by harmful bacteria that enter the body after being ingested as part of or on a food product. Biological contamination causes these harmful germs to be transferred onto food products, which can then cause food poisoning in the person who eats them.
Whilst the potential consequences of cross-contamination can be severe, the steps that need to be taken to reduce the risk of it are quite easy to follow. Being able to identify the most common contamination vehicles is a key part of this, and having this knowledge means that everyone working in a food preparation or manufacturing environment can keep themselves and their customers safe.
If you would like more information on food safety and cross-contamination, have a browse through a range of our online Food and Hygiene courses.