United States
Hong KongTime as a Public Health Control
The FDA model code permits documented time control in defined cases: generally 4 hours for food starting at 41°F or below or 135°F or above, or 6 hours for food starting at 41°F or below and kept at 70°F or below.
- Mark each item and serve, cook and serve, or discard it within the limit; local adoption controls.
On this page5 sections
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 | Cold: 41°F or below; hot: 135°F or above. Limited cut/open TCS foods may start at 70°F or below | 5°C (41°F) or below |
| Maximum during the period | Generally not monitored; cut/open exceptions must remain at or below 70°F | Must not exceed 21°C (70°F) |
| Duration | 4 hours | 6 hours |
| At the end | Cook and serve, serve if ready-to-eat, or discard by 4 hours | Cook and serve, serve if ready-to-eat, or discard by 6 hours; discard sooner if above 70°F |
| Can it be refrigerated instead | No | No |
The clock never pauses. By the deadline, food must be cooked and served, served if it is ready-to-eat, or discarded. It cannot be returned to refrigeration to start a new holding period. For the six-hour method, discard sooner if the warmest part rises above 70°F.
What the written procedure needs
- Which foods the procedure applies to.
- The starting temperature and required monitoring for the selected method.
- How each item is marked with the time it left control and the time it must be discarded.
- That food is cooked and served, served if ready-to-eat, 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. Mark the required end time when the food leaves control; an unmarked item must be discarded.
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
Time control is not a way to rescue food that has already been out too long, and it cannot be an unwritten habit. The FDA model code bars an establishment serving a highly susceptible population from using this option for raw eggs; that is a targeted restriction, not a blanket ban on every food in those establishments.
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.
Apply the method the stem specifies. Under the four-hour method, five hours exceeds the limit. Under the six-hour method, check both elapsed time and the warmest-part temperature; a reading above 70°F requires discard. Temperature is monitored for the six-hour method, but not used to extend a four-hour limit.
Common questions
What is the four-hour rule?
Under the FDA model code, food must begin at the permitted temperature, be marked with its four-hour deadline, and be cooked and served, served if ready-to-eat, or discarded within the period. The adopted local code controls.
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 must be cooked and served, served if ready-to-eat, or discarded within the applicable time limit; returning it to refrigeration does not restart the clock.
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.