Foodborne Illness and Food Safety Hazards
What the exam tests
This domain checks whether you can classify a hazard correctly, recognise foods that support bacterial growth, and explain why certain handling errors cause illness rather than merely spoilage.
Hazards and high-risk foods
- Biological: bacteria (e.g. Salmonella, Listeria, E. coli O157:H7, Staphylococcus aureus, Bacillus cereus), viruses (norovirus, hepatitis A), parasites and moulds. Bacteria are the main cause of foodborne illness in food service.
- Chemical: cleaning chemicals, pesticides, unapproved additives, toxin from damaged cans, allergen cross-contact.
- Physical: glass, metal, stones, bones, plasters, packaging.
- Allergens are a chemical/biological hazard legally requiring declaration and separation; an allergy is not the same as intolerance.
High-risk or TCS foods are moist, protein-rich and low-acid: meat, poultry, seafood, eggs, dairy, cooked rice, pasta, cut melons, leafy greens. Bacteria need FATTOM: Food, Acid (low), Temperature, Time, Oxygen (or lack of it) and Moisture. The danger zone is 5–60°C; keep cold food at or below 5°C and hot food at or above 60°C. Toxins from S. aureus and B. cereus are heat-stable, so reheating does not make the food safe.
Worked example
A tray of cooked rice is left in a warm kitchen from 6 p.m. to 6 a.m. It smells normal. Is it safe? No. Bacillus cereus spores survive cooking, germinate at warm temperatures and produce an emetic toxin. The toxin is not destroyed by reheating, and smell is not a reliable test. The rice should have been cooled rapidly and refrigerated, then reheated once to 74°C.
Traps that cost marks
- Assuming freezing or reheating destroys all hazards.
- Using taste, smell or appearance as a safety test.
- Treating allergens as a quality issue rather than a safety hazard.
- Forgetting that viruses and parasites do not multiply in food but still need control.