Cold chain refers to a special supply chain system in which perishable food is always in the low temperature environment necessary for products in all links of product processing, storage, transportation, distribution and retail after being purchased or fished from the origin, so as to ensure food quality and safety, reduce loss and prevent pollution.
The statement 'In order to save energy, the refrigerator selling popsicles in the canteen of the campus supermarket stops for one hour every five hours' is an example of cold chains according to the definition above.