Foil container lids are used for sealing, insulation or isolation. However, if someone uses the wrong material, they can easily cause problems in use.
For example, thin foil lids are easy to deform under heavy pressure or high temperature. Some consumers like to mix different lids. For example, they use plastic lids in the oven. They also use cardboard lids to store liquid food.
This article will explain how people often misuse aluminum foil container lids. It will also show the right way to use them.
Main Foil Container Lids
Cardboard lid, foil lid and plastic lid are three typical types of aluminum foil container lids. The following are their materials and temperature resistance:
The cardboard lid has white paper on one side and aluminum foil on the other. When in use, the white paper faces up and the aluminum foil side contacts the food.
Manufacturers mainly use aluminum foil containers with cardboard lids for ready-to-eat foods and packaging. Cardboard lids can handle temperatures from -20°C to 100°C. This depends on the liner material.
For example, PLA coating can only resist about 60°C. In contrast, a water-based barrier layer or PE coating can withstand over 90°C. It is also suitable for refrigeration.
Manufacturers make the foil lid from aluminum. This material can handle temperatures from -40°C to 220°C.
This makes it safe for use in ovens, microwaves, and for frozen storage. If the outer layer is plastic (such as PP or PET), the temperature resistance may drop to about 120°C. Aluminum foil containers with foil lids are suitable for takeaway boxes, baking containers and aluminum foil trays for ovens.
The temperature range of transparent plastic lids depends on the material. PP plastic lids can withstand -20°C to 120°C, suitable for microwave heating, but not high temperature baking. PET lids can withstand temperatures from -30°C to 70°C, suitable for refrigeration and avoid high temperatures.
If you are unsure about the material, check the product packaging for instructions. You can also contact the supplier for more information.
Cases of Improper Use
Can I Microwave The Cardboard Lid
Can I leave the lid on or put it in direct contact with the oven when heating in the microwave? The cardboard lid has poor heat resistance. If it touches the oven wall or gets very hot for a long time, it can easily burn or release harmful substances.
The heat from the microwave easily deforms or burns the cardboard lid. You cannot use it directly in the microwave. You should remove it and heat it separately or with a high-temperature-resistant aluminum foil lid.
Are Plastic Lids Microwave Safe
Foil containers with plastic lids can be heated in the microwave for a short time. Make sure the lid says “microwave safe.” If the PP plastic lid is used in the oven or high-temperature cooking, it may release harmful substances such as bisphenol A.
Moreover, disposable plastic lids are easily worn and deformed after repeated washing, which is harmful to food safety.
Are Foil Lids Safe at High Temperatures
Using the foil lid in the oven or over an open flame can cause a fire. This happens if the temperature gets too high. The right way to use it is for medium to low temperature heating.
For example, cover it for a short time after preheating the oven. This helps avoid direct contact with flames or long exposure to high temperatures.
At the same time, do not use the aluminum foil lid to wrap acidic foods such as lemons, vinegar, and tomatoes. Choose an aluminum foil cover with a food-grade coating. Reusing a washed aluminum foil lid will make it lose its sealing ability. This happens because the material can thin or crack.
