What each letter stands for
The six conditions are worth learning as a set, because they explain why the rules exist rather than asking you to memorise them one by one.
- Food — bacteria need nutrients, especially protein and carbohydrate. This is why moist, protein-rich foods are classed as potentially hazardous.
- Acidity — most food-poisoning bacteria prefer neutral or slightly acidic conditions, around pH 4.6 to 7.5. Vinegar, citrus and fermentation push food out of that range.
- Time — given a few hours in good conditions, a harmless number of bacteria becomes a dangerous one. Some can double roughly every twenty minutes.
- Temperature — growth is fastest between 5°C and 60°C, the temperature danger zone.
- Oxygen — most need oxygen, though some, like Clostridium, grow without it, which is why vacuum-packed and canned foods have their own rules.
- Moisture — bacteria need available water. Drying, salting and sugaring all work by locking water away.
This comes up on the test — and the training that covers it is free to read.
Start the Free TrainingWhy it's the most useful thing on the course
Almost every control you'll be taught is really about removing one of these six. Refrigeration takes away temperature. The 2-hour / 4-hour rule takes away time. Drying and curing take away moisture. Pickling takes away favourable acidity. Vacuum packing changes oxygen. Once you see that, the rules stop being a list to remember and start being one idea applied six ways.
In practice you rarely control all six. On a normal shift you control two — time and temperature — because they're the two you can actually change with a fridge, a thermometer and a clock. That's why those two dominate the rest of the training.