Survival of Salmonella typhimurium ATCC 14028 on the surface of chicken legs or in mechanically deboned chicken meat gamma irradiated in air or vacuum at temperatures of -20 to +20 C

Control of Salmonella enterica Typhimurium in chicken breast meat by irradiation combined with modified atmosphere packaging

Salmonella is one of the leading causes of human foodborne illnesses originating from meat and poultry products. Cross-contamination of Salmonella from raw to cooked products continues to be problematic in the food industry. Therefore, new intervention strategies are needed for meat and poultry products. Vacuum or modified atmosphere packaging (MAP) are common packaging techniques used to extend the shelf life of meat products. Irradiation has been well established as an antibacterial treatment to reduce pathogens on meat and poultry. Combining irradiation with high-CO(2)+CO MAP was investigated in this study for improving the control of Salmonella enterica Typhimurium on chicken breast meat. The radiation sensitivities (D10-values) of this pathogen in chicken breast meat were found to be similar in vacuum and in high-CO(2)+CO MAP (0.55 ± 0.03 kGy and 0.54 ± 0.03 kGy, respectively). Irradiation at 1.5 kGy reduced the Salmonella population by an average of 3 log. Some Salmonella cells survived in both vacuum and high-CO(2) + CO MAP through 6 weeks of refrigerated storage following irradiation. This pathogen also grew in both vacuum and MAP when the product was held at 25°C. This study demonstrated that irradiation is an effective means of reducing Salmonella on meat or poultry, but packaging in either vacuum or MAP had little impact during subsequent refrigerated storage.

Survival of Pseudomonas fluorescens and Salmonella typhimurium after electron beam and gamma irradiation of refrigerated beef

The radurization effects of gamma ray and electron beam irradiation at 1.5 and 3.0 kGy on beef steaks inoculated with Salmonella Typhimurium and Pseudomonas fluorescens were investigated during 8 days of storage at 5 degrees C. Total bacterial counts and numbers of Salmonella Typhimurium and P. fluorescens were analyzed at 2-day intervals. Total bacterial counts of samples irradiated by both gamma rays and electron beam were significantly (P < 0.05) reduced by 3.8 to 5.3 log CFU/g. Salmonella Typhimurium was not detectable during the experimental period. P. fluorescens counts of beef samples irradiated by gamma rays at both 1.5 and 3.0 kGy were not detected; however, P. fluorescens in samples irradiated by electron beam at 1.5 and 3.0 kGy was recovered after 2 days, and bacterial counts reached 7.8 and 6.9 log CFU/g, respectively. Both gamma ray and electron beam irradiation reduced total bacterial counts initially, possibly extending shelf life. Irradiation was very effective in destroying Salmonella Typhimurium; however, P. fluorescens was not completely eliminated by electron beam irradiation. Consequently, gamma ray irradiation was more effective than electron beam irradiation in the destruction of P. fluorescens.

Elimination of Escherichia coli O157:H7 in meats by gamma irradiation

Undercooked and raw meat has been linked to outbreaks of hemorrhagic diarrhea due to the presence of Escherichia coli O157:H7; therefore, treatment with ionizing radiation was investigated as a potential method for the elimination of this organism. Response-surface methods were used to study the effects of irradiation dose (0 to 2.0 kGy), temperature (-20 to +20 degrees C), and atmosphere (air and vacuum) on E. coli O157:H7 in mechanically deboned chicken meat. Differences in irradiation dose and temperature significantly affected the results. Ninety percent of the viable E. coli in chicken meat was eliminated by doses of 0.27 kGy at +5 degrees C and 0.42 kGy at -5 degrees C. Small, but significant, differences in radiation resistance by E. coli were found when finely ground lean beef rather than chicken was the substrate. Unlike nonirradiated samples, no measurable verotoxin was found in finely ground lean beef which had been inoculated with 10(4.8) CFU of E. coli O157:H7 per g, irradiated at a minimum dose of 1.5 kGy, and temperature abused at 35 degrees C for 20 h. Irradiation is an effective method to control this food-borne pathogen.