Refrigeration in the food trades—meats and fish

Animals when slaughtered are at a body temperature of 39°C. The carcass cools slightly as it is being dressed, but must be put into refrigerated chambers as soon as possible. The speed of cooling depends on the thickness of the joint, so the larger carcasses are usually halved into sides. During the initial cooling stage, careful design of the coolers and their operation is needed to reduce weight loss by evaporation from the surface. A good air circulation is required at a humidity level of 90–94%, so as to keep the surface dry without too much dehydration. In order to maintain a good and steady air circulation around the carcasses at this time, they are hung from rails. A lot of meat is boned or produced as the final cuts, in the factory. For this, the meat needs to be at 0°C or just below. Fresh pork has a shorter shelf life than beef, but it is handled in the same way and at the same chill-room temperatures. Poultry is immersed in hot water just after slaughter, in order to loosen the feathers for the plucking process. The carcasses are then eviscerated and chilled as soon as possible by cold air blast or using iced water in the form of a bath or spray. Most fish is still caught at sea and must be cooled soon after it is taken on board, and kept cold until it can be sold, frozen or otherwise processed. The general practice is to put the fish into refrigerated sea water tanks, kept down to 0°C by direct expansion coils or a remote shell-and-tube evaporator.