Microbiological changes and shelf life of MAP, irradiated fresh pork

Physical, Chemical and Sensory Changes in Irradiated Fresh Pork Packaged in Modified Atmosphere

“…For example, nonirradiated meat packaged with 20% 0, and stored at 5°C had a sensory shelf life of 4 days. However, note that similarly packaged meat, irradiated at 1 kGy was immediately rejected on the basis of strong off-odor and complete discoloration, although that treatment was microbiologically acceptable until day 31 (Lambert et al, 1992). The odor score does not correlate, however, with the low TBA value obtained at day 0 and 3 for that treatment (Fig.…”

“…The resulting consumption of 0, and reduction in the O2 tension at the meat surface favor the oxidation of myoglobin to brown metmyoglobin (Seideman et al, 1984). Indeed, total aerobic counts on the same samples we used were higher in aerobically-packaged samples compared to N,-packaged samples (Lambert et al, 1992).…”

“…The observed decrease in odor for samples packaged with 20% O2 and irradiated at 1 kGy may be due to the fact that upon storage at S'C, the irradiation odor was dissipating. In addition, the microbiological population of these samples was mainly composed of lactic acid bacteria (Lambert et al, 1992) which do not product strong off-odors (McMeekin, 1982). Comparatively, samples irradiated in the absence of O2 had a weaker initial off-odor, but the score for odor increased during storage due to the growth of spoilage microorganisms.…”

Kinetics of ultraviolet light inactivation of Escherichia coli O157:H7 in liquid foods

“…Stock cultures of non‐acid‐ and acid‐adapted cells were prepared by inoculating 100 ml of TSB (pH 7.0) and TSB (pH 5.0) adjusted with 1 M HCl5, 16, 17 with 1 ml of the working culture. Broths were incubated at 37 °C for 15 h to give stock cultures of approximately 10 9 CFU ml −1 , as determined by standard plate count methodology 18…”

“…The delivered UV dose was calculated as the product of intensity and time. Total aerobic plate counts after each UV treatment were done, in duplicate, on TSA plates as outlined by Lambert et al 18 To determine the level of injured E coli O157:H7 cells, serial dilutions of the treated samples were spread on selective SMA plates. All plates were incubated aerobically at 37 °C for 24 h and counts on TSA and SMA plates were compared and expressed as CFU ml −1 .…”