United States
Hong KongUsing time instead of temperature: the four-hour and six-hour rules
Time alone may replace temperature control for up to 4 hours from when food leaves temperature control, after which it is discarded. A 6-hour option applies where food starts at 5°C (41°F) and never exceeds 21°C (70°F). Both need a written procedure and marking.
Time control is a deliberate decision made in advance, not a description of what happened. That distinction is the whole topic.
The two options
| Four-hour | Six-hour | |
|---|---|---|
| Starting temperature | Any, in compliance | 5°C (41°F) or below |
| Maximum during the period | Not monitored | Must not exceed 21°C (70°F) |
| Duration | 4 hours | 6 hours |
| At the end | Discard | Discard |
| Can it be refrigerated instead | No | No |
The last row surprises people every time. Food on time control is discarded at the end of the period. It does not go back in the cooler, because the whole point was that temperature was not being controlled.
What the written procedure needs
- Which foods the procedure applies to.
- The starting temperature, where the six-hour option is used.
- How each item is marked with the time it left control and the time it must be discarded.
- That the food is served or discarded within the period.
- That it is discarded if unmarked, or if the mark is illegible.
That final line is the enforcement mechanism. Unmarked food on time control is discarded on discovery, because nobody can prove when the clock started.
It runs from when food leaves temperature control, not from when service starts. Pizza slices taken out at eleven and put on the counter at noon have already used an hour, and a question built around that gap is testing exactly this.
Where it is genuinely useful
Pizza slices on a counter. A busy sandwich line where the make table cannot keep up. Display of pastries containing cream. Buffets where equipment is limited. Off-site catering with no power.
In each case the operation has decided in advance that temperature will not be maintained, and has substituted a defensible control.
Where it is not
As a way of rescuing food that has already been out too long. As an unwritten habit. And in establishments serving highly susceptible populations, where the option is restricted.
How the exam asks it
Usually as a scenario with a clock in it. Food out at ten, question asked at three, and four options offering: serve it, refrigerate it, discard it, or check the temperature.
Discard. Five hours on the four-hour rule, and checking the temperature is irrelevant because temperature stopped being the control the moment the food left the cooler.
Common questions
What is the four-hour rule?
Food may be held without temperature control for up to four hours from when it leaves control, provided there is a written procedure and the food is marked. At four hours it is discarded.
When does the six-hour option apply?
When the food starts at 5°C (41°F) or below and never exceeds 21°C (70°F) during the period. It requires monitoring the temperature, which the four-hour option does not.
Can food on time control be refrigerated instead of discarded?
No. It is discarded at the end of the period. Returning it to refrigeration is not permitted, because temperature control was deliberately not being applied.
When does the clock start?
When the food leaves temperature control, not when service begins. Food removed from a cooler an hour before service has already used an hour of the period.
What happens to unmarked food on time control?
It is discarded on discovery, because there is no way to establish when the period began. The marking requirement is what makes the whole system enforceable.