G-Flute trays are rated for service temperatures from −28 °C to +220 °C. That single line on a specification sheet covers a long journey: filling at ambient temperature, baking, cooling, blast freezing, frozen storage, distribution and, for many products, reheating at home or in food service. This article explains what the range means and how to check it against your own process.
What a service temperature range describes
A service temperature range is the band of temperatures in which the tray is designed to perform its function: keep its shape, carry the product and protect it. It is not a single test result. It summarises behaviour at the cold end, where materials can become brittle, and at the hot end, where they can lose stiffness or discolour.
The cold end: −28 °C
Most frozen bakery products are stored at around −18 °C, and blast freezers run colder for short periods. A lower limit of −28 °C gives margin for both. At the cold end, the questions are practical:
- Does the tray stay rigid enough to stack when frozen?
- Does condensation on thawing weaken the board?
- Does the product release cleanly after freezing?
Barrier finishes help at this stage, because they limit how much moisture from the product reaches the fiber.
The hot end: +220 °C
Typical bread and cake bakes sit between about 160 °C and 220 °C, depending on product and oven type. The oven setting is not the same as the temperature the tray reaches: a tray filled with batter stays far cooler than the air around it for most of the bake, because the product absorbs the heat. Exposed rims and empty corners run hotter.
That is why the oven profile matters as much as the rating. A product baked at 200 °C for 25 minutes in a full tray is a different case from an empty tray passing through the same oven.
Reheating
Many products baked in G-Flute trays are reheated by the consumer or in food service. Fiber-based trays can go into conventional ovens and microwaves. Metallized barrier finishes are not intended for microwave use.
How to check the range against your process
- Map every temperature step from filling to consumption, including dwell times.
- Mark the hottest and coldest points the tray will see, including empty edges.
- Confirm both sit inside the rated range with margin.
- Run a line trial with a full production cycle, including freezing and reheating where relevant.
One tray for the whole cycle
When one tray covers the full cycle, the product is never transferred. That removes a handling step, reduces damage and lets the baking tray become the retail pack. Read more about the board build on the G-Flute technology page.
