5 Influence of refrigeration on evaporative weight loss from meat From the moment an animal is slaughtered the meat produced begins to lose weight by evaporation. Under typical commercial distribution condi tions, it has been estimated that lamb and beef lose from 5.5 to 7% by evap- oration between slaughter and retail sale(Malton, 1984). Weight losses from pork are probably of the same magnitude. In addition to the direct loss in saleable meat there are also secondary losses. Excessive evaporation during nitial chilling and chilled storage produces a dark unattractive surface on the meat. Either this has to be removed by trimming, or the meat is down- graded and sold at a reduced price Freezing does not stop weight loss. After meat is frozen, sublimation of ice from the surface occurs. If the degree of sublimation is excessive, the surface of the meat becomes dry and spongy, a phenomenon called'freezer burn. In the United States, weight loss resulting from a combination of direct evaporative loss and freezer burn in pork bellies stored for one month before curing was estimated to be 500000kg(Ashby and James, 1974). Since that report, developments in the use of moisture imperious packaging materials have significantly reduced sublimation in frozen meat Over 4000000 tonnes of meat and meat products are sold in the UK per year(MAFF, 2000). A very conservative estimate is that the use of existing technology in the field of refrigeration could reduce evaporative loss by at least 1%. This would result in a minimum saving to the UK meat industry of f60000000(E96m)per annum In this chapter the theoretical factors that govern evaporative loss briefly discussed. Comparisons are then made between weight losses commercial practice and those resulting from the use of more closely con- trolled refrigeration techniques throughout the cold chain. The data for this5 Influence of refrigeration on evaporative weight loss from meat From the moment an animal is slaughtered the meat produced begins to lose weight by evaporation. Under typical commercial distribution condi￾tions, it has been estimated that lamb and beef lose from 5.5 to 7% by evap￾oration between slaughter and retail sale (Malton, 1984).Weight losses from pork are probably of the same magnitude. In addition to the direct loss in saleable meat there are also secondary losses. Excessive evaporation during initial chilling and chilled storage produces a dark unattractive surface on the meat. Either this has to be removed by trimming, or the meat is down￾graded and sold at a reduced price. Freezing does not stop weight loss. After meat is frozen, sublimation of ice from the surface occurs. If the degree of sublimation is excessive, the surface of the meat becomes dry and spongy, a phenomenon called ‘freezer burn’. In the United States, weight loss resulting from a combination of direct evaporative loss and freezer burn in pork bellies stored for one month before curing was estimated to be 500 000 kg (Ashby and James, 1974). Since that report, developments in the use of moisture imperious packaging materials have significantly reduced sublimation in frozen meat. Over 4 000 000 tonnes of meat and meat products are sold in the UK per year (MAFF, 2000). A very conservative estimate is that the use of existing technology in the field of refrigeration could reduce evaporative loss by at least 1%. This would result in a minimum saving to the UK meat industry of £60 000 000 (€96 m) per annum. In this chapter the theoretical factors that govern evaporative loss are briefly discussed. Comparisons are then made between weight losses in commercial practice and those resulting from the use of more closely con￾trolled refrigeration techniques throughout the cold chain. The data for this