Cross-contamination

Cross-contamination is the transfer of residues of one product, raw material or contaminant into another product.

Cross-contamination can occur when different products pass through the same equipment, pipes or tanks, and something is left behind from the previous product. It can also occur via tools, packaging, air, or workers’ hands and clothing.

The consequences depend on what has been transferred:

• a change in product properties, such as a different colour, taste or smell,
• allergens, such as nuts, gluten or milk in a product whose label states that it does not contain them, which is dangerous for people with allergies,
• microbiological contamination, meaning bacteria or moulds carried over from one product to another,
• chemical residues, for example from cleaning agents.

In the food and cosmetics industries, cross-contamination can lead to product recalls, fines and a loss of customer trust. It is prevented by measures such as thorough cleaning, separating the production of products containing allergens, the right production sequence and designing equipment so that no residues remain inside.

Example: A bakery produces bread with and without sesame on the same line. If the equipment is not thoroughly cleaned after a sesame run, sesame seeds may end up in bread whose label states that it contains no sesame. A person allergic to sesame could have a severe allergic reaction after eating it. That is why the bakery first produces the sesame-free bread and only then the bread with sesame, and thoroughly cleans the line after every sesame run.