In hospitals, schools and hotels the distance from kitchen to service is short but the food waits until service time, and the trolley's job is to hold temperature through that wait. According to WHO, 5 to 60 degrees is the range where microorganisms multiply very fast, so the hot compartment should stay above it and the cold one below.
| Trolley | What it does | When |
|---|---|---|
| Insulated | Loses temperature slowly | Short wait |
| Heated | Keeps hot compartment active | Long service period |
| Refrigerated | Keeps cold compartment active | Salads, desserts |
| Combined | Both compartments together | Tray service |
Measure the wait for a week: write down the minutes between food leaving the kitchen and the first plate being served, and take the longest wait, not the average. An active model needs a socket, so know in advance where the trolley will stand at the service point.
In a combined trolley, weak insulation between the hot and cold compartments cools the hot food and warms the cold. In the trial, measure each dish at its own point and do not mix compartment air readings with food readings. Try the loaded trolley through doors, lifts and ramps, and check that the shelves come out for washing.
