The gap between hot food and outside air is more than twice the gap for a chilled load, which is why the same container holds hot food for less time. In 25-degree air a 4-degree chilled product is 21 degrees from the outside air, while 70-degree food is 45 degrees from it. Heat through the wall follows that gap, so heat leaves hot food roughly twice as fast as it enters a chilled load.
| Subject | Cold transport | Hot transport |
|---|---|---|
| Edge of the danger zone | Above 5 °C | Below 60 °C |
| Gap to 25 °C air | 21 degrees for a 4 °C product | 45 degrees for 70 °C food |
| What extends the time | Eutectic plates, dry ice | Pre-heated container, full load |
On a hot round, the steps that extend the time are taken at loading:
- warm the container with hot water before the food goes in, or the container draws the first heat from the food
- fill gastronorm pans to the top; air in a half-empty pan cools quickly
- put the probe in the core of the smallest portion; the air in the box does not show the food
- put the delivery with the most stops at the start of the round
Hot food gives off steam; in a closed box it condenses under the lid and drips back onto the food, spoiling its look and texture. So a hot container is left open to dry after every round. The GEBHARDT EPP thermobox withstands -30 to +80 °C and is dishwasher safe. When hot and cold loads share a vehicle, they travel in separate containers and separate zones.
