Food safety and preparation
Design & Technology · Key Stage 3 · The School
How illness spreads
Most food poisoning comes from bacteria multiplying or from CROSS-CONTAMINATION — bacteria moved from raw food to ready-to-eat food by hands, boards, cloths or knives. Raw meat, poultry, eggs and unwashed vegetables are the usual sources. Bacteria are invisible and often change nothing about how food looks or smells, which is why the rules are followed rather than judged by eye.
The temperatures
Bacteria multiply fastest roughly between 5°C and 63°C — the DANGER ZONE. A fridge below 5°C slows them; cooking above 75°C in the centre kills most of them. Reheated food must be piping hot right through, and cooling should be quick rather than leaving food out. A probe thermometer settles what guessing cannot.
In practice
Wash hands before starting and after touching raw meat. Keep separate boards for raw and ready-to-eat. Store raw meat at the bottom of the fridge so nothing can drip onto food below. Do not wash raw chicken — it sprays bacteria around the sink. All practical cooking should be done with an adult present; this lesson is the knowledge behind it.
Bacteria multiply fastest between 5 °C and 63 °C. A fridge should be at or below 5 °C; hot food held for service must stay above 63 °C; cooking should reach 75 °C in the centre, checked with a probe in the thickest part. So chicken left on a worktop for three hours has been sitting in the middle of that range the whole time — and it will neither look nor smell any different afterwards.