Food Safety, Hygiene and Preservation
What you must understand
Food poisoning is usually caused by bacteria such as Salmonella, Staphylococcus aureus, Clostridium perfringens, Escherichia coli and Listeria. Bacteria need warmth (about 5–63 °C is the danger zone), moisture, food and time to multiply. Know the symptoms and the high-risk foods: cooked meat, poultry, eggs, dairy, rice and shellfish.
Apply personal, kitchen and food hygiene: wash hands, wear clean protective clothing, cover hair and cuts; keep work surfaces clean, separate raw and cooked foods, use colour-coded boards, wash fruit and vegetables, cook thoroughly, cool food quickly and refrigerate below 5 °C, reheat to steaming hot, and keep pests out.
Preservation slows or stops spoilage: refrigeration and freezing (cold), drying (removes water), salting and sugaring (bind water), pickling in vinegar (acid), canning and bottling (heat and sealed), smoking, and irradiation. Know what each method does and one local example.
Traps in questions
- Saying food "should be hot" without giving a temperature.
- Forgetting that reheated food should be heated until steaming hot, and only once.
- Confusing preservation principles: salting and drying both remove available water.
- Ignoring cross-contamination from a cloth, knife or hands.
Worked rule of thumb
For any "why did this person become ill?" question, trace the chain: source → hands/equipment → food → time in danger zone → eaten. Naming the break in the chain earns the marks.