BACTERIOLOGICAL, PHYSICOCHEMICAL, AND SENSORY QUALITY OF FRESH PORK CHOPS WITH LOW-DOSE IRRADIATION AND MODIFIED-ATMOSPHERE PACKAGING

The combined effects of low-dose irradiation and modified-atmosphere p ackaging treatments were studied with respect to survival and growth o f salmonellae and changes in physicochemical and sensory characteristi cs of fresh pork loin chops. Fresh trimmed pork loin chops were inocul ated with salmonellae (about 10(3) to 10(4) CFU/g), packaged with air, vacuum, 25% CO2, 50% CO2, or 75% CO2 balanced with N-2, and irradiate d by 0 or 1.0 kGy electron beam. All samples were stored at 2 to 4 deg rees C for 2 weeks, followed by storage at 25 degrees C for 1 day. Uni noculated samples were also subjected to the same treatments and store d at the same refrigeration temperature for 4 weeks with weekly measur ements of color, purge loss, and thiobarbituric acid (TEA) values, as well as panel evaluations for color and odor. The number of salmonella e was initially reduced by 0.3 to 1.4 log cycles by 1.0 kGy irradiatio n, depending on packaging atmospheres applied. Salmonellae were mon se nsitive to irradiation in the presence of air. Using combinations of 1 .0 kGy irradiation with a vacuum or elevated CO2 levels resulted in no survival of salmonellae after 2 weeks of storage at 2 to 4 degrees C, and no further recovery after one more day at abuse temperature. Comb ined treatments also helped to slow the physicochemical and sensory ch anges in irradiated fresh pork chops. Vacuum packaging maintained pink color in irradiated pork, but showed greater purge loss and relativel y high TEA values in comparison with CO2 atmospheres; all CO2 atmosphe res resulted in less desirable irradiated pork color after 2 weeks of storage.