Section 8.1 of the Ministry of Agriculture and Forestry's guide 'Hygiene Principles and Good Practice Guide for Mass-Catering Premises' (Guide No. 5) sets two limits: food to be held hot must not fall below 65 °C, and it must not be held at that temperature for more than 3 hours. The foreword states that application rests on a voluntary basis.
If the record holds only kitchen departure and service start, the transfer between vessels, the transport and the wait before service stay invisible.
| Measuring point | Write down |
|---|---|
| Kitchen departure | time, temperature, batch ID |
| Handover | time, temperature, how many times the lid was opened |
| Service start and end | time, temperature, operator and method |
Measure the same vat at these three points for a day and it becomes clear whether the loss happens in transport or at service. The time an insulated container buys depends on wall thickness, fill and how often the lid opens; measure it once with a full container instead of guessing.
A worked example of a record
The values below are an example, not a measurement from any kitchen. They show how a record is read.
| Time | Measuring point | Temperature | 65 °C and above |
|---|---|---|---|
| 09:00 | Kitchen departure | 85 °C | Yes |
| 10:10 | Handover | 74 °C | Yes |
| 11:40 | Service start | 66 °C | Yes |
| 13:00 | Service end | 62 °C | No |
The fall per minute is about 0.16 °C from departure to handover (11 °C in 70 minutes), about 0.09 °C from handover to service start (8 °C in 90 minutes) and about 0.05 °C to service end (4 °C in 80 minutes). The fall slows as the gap to the surroundings shrinks, and in this example the largest loss sits in the first stage.
Between service start (66 °C) and service end (62 °C), a straight-line estimate puts the crossing of 65 °C at about 12:00; it is an estimate, because the curve bends each time the lid opens. The guide does not say from which moment the three hours are counted. Counted from kitchen departure at 09:00, 12:00 is exactly three hours, so in this example the limit is used up in the same minute the food drops below 65 °C.
At the service point. The guide defines the purpose of a bain-marie as keeping food at a set temperature, not heating cold food. It is not a solution for food that has already cooled at handover. Where there is no power at the service point, the only remaining lever is shortening the gap between handover and service: sending the food close to service time, not early. That requires the route plan to be set together with the menu.