This rule is very commonly confused with the Cooling Rule, so let me try to simplify it.
So, the 2 Hour 4 Hour rule is based on scientific evidence that food can be held out of temperature control, i.e. between 5°C & 60°C for short periods of time as follows:
- Between 0 to 2 hours: use immediately or refrigerate at ≤5°C
- 2 to 4 Hours: use immediately/consume – do not return to refrigeration!
- After 4 Hours: Discard
However, the key factor to remember when using Time as a Control, is that Time is Cumulative, so the clock starts ticking right from the time you Receive & Store the food, to Preparation, Service / Display.
The other factors to consider when applying the rule are:
- Avoid displaying in excessive heat e.g. direct sunlight;
- Ensure storage, display and service equipment is clean.
Remember, it is important to maintain evidence and records to demonstrate the correct use of the rule, when working with Potentially Hazardous Foods.