Food Safety Hazards and Contamination
What this domain tests
The exam checks whether you can identify a food safety hazard, distinguish it from contamination, and trace how contamination reaches food. A hazard is anything with the potential to cause harm; contamination is the presence of that hazard in food. Questions often ask for the most likely route, not the most dramatic one.
Hazard categories and routes
- Biological: bacteria, viruses, moulds, parasites. The main concern in catering.
- Chemical: cleaning chemicals, pesticides, unlabelled decanted fluids, toxic metals, mycotoxins.
- Physical: glass, metal, plastic, bones, pests, packaging.
- Allergenic: a protein that triggers an immune response in a susceptible person; not a hazard to everyone, but a hazard to some.
Contamination arrives by four routes: hands, surfaces/equipment, pests, and food-to-food contact. Direct cross-contamination is raw food touching ready-to-eat (RTE) food. Indirect is via a vehicle such as a knife, cloth, board, tap handle or fridge shelf.
Worked example
A chef chops raw chicken on a red board, wipes the board with a damp cloth, then slices cooked ham on the same board. The ham is RTE. The hazard is Campylobacter or Salmonella from the chicken; the board is the vehicle; the damp cloth spreads the contamination rather than removing it. The correct control is separate board/knife for RTE, or clean and disinfect the board before reuse. Wiping without detergent and disinfectant is not enough.
Marks-losing traps
- Calling the board a "hazard" - it is a vehicle.
- Ignoring allergenic hazards because they are not infectious.
- Saying "cross-contamination" without naming the direction (raw to RTE).
- Assuming food is safe because it looks, smells and tastes normal.