Chilled and frozen retail display 233 been previously frozen and thawed before display. Overageing of meat can limit its display life. Bell et al. (1996) found that hot-boned bull beef aged at 5'C for 6 days could only be displayed for 24 h at 5C before it was unac ceptable because of its dull dark lean tissue and grey to green discoloration of the fat. Similar meat that was unaged but also stored for 70 days -1.0±0.5° could be displayed for48h Retail display characteristics of steaks from hot-boned logissimus dorsi (LD)and M. semimembranosus(SM)muscles from electrically stimulated sides were found to be similar to those from cold-boned unstimulated sides (Griffin et aL., 1992). Whole muscles from both treatments were stored for up to 21 days before cutting into steaks. The colour of the lean from meat stored for 21 days was brighter than that stored for 7 or 14 days. Lean colour, fat colour and overall appearance scores all decreased with time over the 5 day display period Previous storage will reduce the display life of meat and it is bette store meat in large pieces. Meat that had been minced before storage lost its red colour more rapidly during display than that minced immediately before display(Madden and Moss, 1987). The addition of carbon dioxide (CO2)prior to storage has a beneficial effect on colour and bacterial growth during display. Additions of 2-4g of solid CO2 per kilogram of meat resulted in growth of total viable bacterial counts similar to that of unstored con trols. However, total anaerobic levels were much higher than controls. Storing prepacked meat in a gas flushed ' bag has been advo- cated as a method of extending the chilled storage life without reducing the retail display life of the packs. Scholtz et al.(1992)packed pork loin chops in individually overwrapped Styrofoam trays which were then bulk packed in vacuum bags which were subsequently inflated with 100%CO2. After up to 21 days storage in the mother bags at 0"C the packs had a subsequent retail display life of 4 days. A retail display life of 4 days could only be attained after storage for 14 days in modified atmosphere packs or for 7 days in vacuum skin packs a display life of 6 days can be achieved in pork loin chops obtained fro resh pork loins and vacuum packed in high oxygen-barrier films(Vrana et al., 1985). The chops were displayed at 2+ 2C for cycles of 14h under an illumination of 1614 lux, followed by 10h in the dark. Under similar con- ditions chops packed in high oxygen-permeable film had a display life of 4 11.1.2 Layout of chilled cabinet a typical cabinet has a refrigeration unit behind the display ed to the chilled air from the refrigeration unit is blown by a fan and delivere relevant area by duct work behind the display area( Fig. 11. 1). After the air has been delivered to the display area it is then drawn back into the duct through a grille and is refrigerated again to continue the cyclebeen previously frozen and thawed before display. Overageing of meat can limit its display life. Bell et al. (1996) found that hot-boned bull beef aged at 5 °C for 6 days could only be displayed for 24 h at 5 °C before it was unac￾ceptable because of its dull dark lean tissue and grey to green discoloration of the fat. Similar meat that was unaged but also stored for 70 days at -1.0 ± 0.5 °C could be displayed for 48 h. Retail display characteristics of steaks from hot-boned logissimus dorsi (LD) and M. semimembranosus (SM) muscles from electrically stimulated sides were found to be similar to those from cold-boned unstimulated sides (Griffin et al., 1992). Whole muscles from both treatments were stored for up to 21 days before cutting into steaks. The colour of the lean from meat stored for 21 days was brighter than that stored for 7 or 14 days. Lean colour, fat colour and overall appearance scores all decreased with time over the 5 day display period. Previous storage will reduce the display life of meat and it is better to store meat in large pieces. Meat that had been minced before storage lost its red colour more rapidly during display than that minced immediately before display (Madden and Moss, 1987). The addition of carbon dioxide (CO2) prior to storage has a beneficial effect on colour and bacterial growth during display.Additions of 2–4g of solid CO2 per kilogram of meat resulted in growth of total viable bacterial counts similar to that of unstored con￾trols. However, total anaerobic levels were much higher than controls. Storing prepacked meat in a gas flushed ‘mother’ bag has been advo￾cated as a method of extending the chilled storage life without reducing the retail display life of the packs. Scholtz et al. (1992) packed pork loin chops in individually overwrapped Styrofoam trays which were then bulk packed in vacuum bags which were subsequently inflated with 100% CO2. After up to 21 days storage in the mother bags at 0 °C the packs had a subsequent retail display life of 4 days. A retail display life of 4 days could only be attained after storage for 14 days in modified atmosphere packs or for 7 days in vacuum skin packs. A display life of 6 days can be achieved in pork loin chops obtained from fresh pork loins and vacuum packed in high oxygen-barrier films (Vrana et al., 1985). The chops were displayed at 2 ± 2 °C for cycles of 14 h under an illumination of 1614 lux, followed by 10h in the dark. Under similar con￾ditions chops packed in high oxygen-permeable film had a display life of 4 days. 11.1.2 Layout of chilled cabinet A typical cabinet has a refrigeration unit behind the display area. The chilled air from the refrigeration unit is blown by a fan and delivered to the relevant area by duct work behind the display area (Fig. 11.1). After the air has been delivered to the display area it is then drawn back into the duct through a grille and is refrigerated again to continue the cycle. Chilled and frozen retail display 233