Does the paper tray become brittle at low temperatures?

1. Principle of the effect of low temperature on paper trays

When the temperature drops into the freezing zone, the water in the paper fibres in the paper tray will precipitate out due to freezing, resulting in weakening of the bond between the fibres and loosening of the structure, which may lead to delamination or cracking of paper trays, such as kraft paper trays.

2. Comparison of paper tray performance in different temperature zones

In a refrigerated environment of 0~10℃, a normal paper tray will slightly harden but basically keep its structure intact, which is suitable for short-term storage of sandwiches, salads and other light meals; a PE-coated kraft paper tray has no obvious change and can normally hold soups or refrigerated pastries. When the temperature drops to -10~0℃, the edges of a normal paper tray will start to crack and the load-bearing capacity will drop by about 30%. PE-coated lunch boxes can still be used for short-term storage, but their flexibility will be reduced, so you need to avoid bending them excessively when opening and closing them. In a standard freezing environment of -18°C, ordinary paper trays will become severely brittle, with an 80% probability of leaking when thawed, making them almost unsafe to use. Therefore, care should be taken when we using paper trays at low temperatures.

If you need to use paper tray temporarily, such as kraft paper tray to freeze food, you can use cling film to wrap the lunch box in multiple layers first, to isolate it from direct contact with low-temperature air; when defrosting, use the gradient warming method, and first move the lunch box to the freezer to raise the temperature by 5℃ every 2 hours, to avoid the sudden change in temperature that causes the fibres to absorb water and expand and rupture quickly.