Why refrigerators have a plastic foam core?

Refrigerators have a plastic foam core because of plastic is a good insulator of heat. It does not absorb heat from the surroundings and helps to balance the temperature between the refrigerator and the surrounding. Plastics have poor thermal conductivity, and it does not allow heat to come inside the refrigerator.

You may have observed that freezers also have a plastic foam core due to the same reason.