Cross-contact: how allergens spread

Cross-contact happens when an allergen gets into food that should not contain it. Some guidance calls this cross-contamination. It differs from bacterial contamination in one important way. Cooking can kill bacteria, but it does not destroy allergens. Once an allergen is in a dish, you cannot take it out.

Allergens travel in tiny traces. Common routes include shared fryer oil, toasters, chopping boards, knives, tongs and ladles. Griddles and woks that are wiped but not properly cleaned also carry allergens. So do hands, gloves, aprons and cloths. In a bakery, flour moves through the air. In a café, a steam wand can carry cow's milk into a plant-based drink.

Here is an example. A takeaway's chips contain only potato and oil, so the recipe shows no allergens. But the chips are fried in the same oil as battered fish. They now carry fish and wheat from the batter, and the allergen information must say so. An allergen record has to show how food is really made, not just what the recipe says.

Service brings more risks. A spoon moves between dishes on a buffet. A garnish is added at the pass. A plate is carried across a table of other food. Cross-contact can happen after food has left the kitchen, so everyone who touches the food has a part to play.

If cross-contact cannot be avoided, you must tell the customer that you cannot provide an allergen-free dish. Saying 'we cannot make this safely' is always better than taking a risk.