Refrigeration is a process which removes heat from a given location. The removal of heat as well as its speed results in a decrease in temperature. Refrigerated transport services use temperature controlled trailers or "reefers". "Reefer" trailers are a type of van trailer with fixed or removable cooling units and polyurethane foam insulation. This insulation helps contain the cool temperature so that subsequent effort on the refrigeration system is reduced. In refrigerated trailers, temperatures can be maintained at a sub-zero temperature for frozen goods or a low plus temperature for chilled goods such as dairy or meat products, fish or seafood and fruit and vegetable products.
Chilled distribution is common in not only the food industry but also the pharmaceutical and chemical sectors where it can be used to move vaccines or hazardous or flammable substances. My own company, WCF Distribution Services, use reefer trailers to haul primarily fruit and vegetables but also dairy products and seafood. In the main our deliveries are to chilled distribution centers run by national multiples. Loading and unloading is done from the rear or side of the trailer by pedestrian or forklift truck, as the goods are usually palletized. Most refrigerated transport services operate between temperature ranges of 2-8 degrees Celsius.
Chilled distribution companies need to be aware of temperature protocols throughout the journey. Chilled temperature regimes are crucial to the maintenance of a product's quality and shelf life capability. For example products such as Spanish iceberg lettuce and broccoli can be harvested, cooled and loaded onto a reefer where, despite a 3 day road/rail journey, they will still be in perfect condition on arrival if the temperature is maintained. Temperature loggers and radio frequency identification RFID tags help in monitoring the temperature history of the product and therefore help determine its remaining shelf life.
Chilled distribution gathered momentum in the mid-eighties particularly as the supermarkets insisted on a refrigerated transport link in the supply chain. It is vital to ensure that goods that are now sourced from all over the world are kept in a state that ensures the utmost quality for the consumer.