RESIDUAL EFFECT OF CO2 ON BACTERIAL COUNTS AND SURFACE PH OF CHANNEL CATFISH

Channel catfish fillet strips were packaged under aerobic atmosphere ( AIR) and under 90% CO2, 7.5% N 2, and 2.5% O2 modified atmosphere pack aging (MAP). Half of the samples from the MAP treatment were repacked under aerobic conditions after 6 d storage (COM). Packaged fish were s tored at 0 and 10-degrees-C for 20 d. Aerobic plate counts reached 8 l og CFU/g by the eighth day for AIR packs and by day 20 for COM packs. Fish in MAP or COM held at 0-degrees-C did not reach above 8 log CFU/g for 20 d, whereas those at 10-degrees-C reached 8 log CFU/g after 4 d . Facultative anaerobic counts were similar in trend to aerobic plate counts but lower in numbers. Fish pH was not affected by temperature b ut changed slightly over time with treatment. The pH of fish packed in AIR did not change, whereas that of MAP treatment decreased from 6.40 to 6.17 by day 12. Holding channel catfish fillet strips at 0-degrees -C under MAP for 6 d and transferring to aerobic conditions for the re mainder of storage, will result in 8 d shelf-life extension.