Refrigeration is a process of moving heat from one location to another.
The work of heat transport is traditionally driven by mechanical work, but can also be driven by heat, magnetism, electricity, laser and other means.
Refrigeration has many applications, including, but not limited to, household refrigerators, industrial freezers, cryogenics, and air conditioning.
Fish fingers are typical frozen food products. Frozen products do not require any added preservatives because microorganisms do not grow when the food temperature is below minus 9.5 degrees Celsius.
Mechanical freezers were the first to be used in the food industry. They function by circulating a refrigerant, normally ammonia, around the system, which withdraws heat from the food product.
The heat is then transferred to a condenser and dissipated into air or water. Frozen food packaging must maintain its integrity throughout the processes of machine filling, sealing, freezing, storing, transporting, thawing and often cooking.