The combined effects of low-dose irradiation and modified-atmosphere packaging treatments were studied with respect to survival and growth of salmonellae and changes in physicochemical and sensory characteristics of fresh pork loin chops. Fresh trimmed pork loin chops were inoculated with salmonellae (about 103 to l04 CFU/g), packaged with air, vacuum, 25% CO2, 50% CO2, or 75% CO2 balanced with N2, and irradiated by 0 or 1.0 kGy electron beam. All samples were stored at 2 to 4°C for 2 weeks, followed by storage at 25°C for 1 day. Uninoculated samples were also subjected to the same treatments and stored at the same refrigeration temperature for 4 weeks with weekly measurements of color, purge loss, and thiobarbituric acid (TBA) values, as well as panel evaluations for color and odor.
The number of salmonellae was initially reduced by 0.3 to 1.4 log cycles by 1.0 kGy irradiation, depending on packaging atmospheres applied. Salmonellae were more sensitive 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°C, and no further recovery after one more day at abuse temperature. Combined treatments also helped to slow the physicochemical and sensory changes in irradiated fresh pork chops. Vacuum packaging maintained pink color in irradiated pork, but showed greater purge loss and relatively high TBA values in comparison with CO2 atmospheres; all CO2 atmospheres resulted in less desirable irradiated pork color after 2 weeks of storage.
Low-dose irradiation reduces forced swim test-induced immobility and oxidative stress in mice