Effect of irradiation of frozen meat/fat trimmings on microbiological and physicochemical quality attributes of dry fermented sausages.

Changes in microbiological and physicochemical quality attributes resulting from the use of irradiation in the production of Greek dry fermented sausage were investigated as a function of fermentation/ripening time. Results showed that irradiating meat/fat trimmings at 2 or 4kGy prior to sausage production eliminated natural contamination with Listeria spp., and reduced pseudomonads, enterococci and pathogenic staphylococci, and enterobacteria, to less than 2 and 1logcfug(-1), respectively. Pseudomonads were very sensitive (>3.4 log reduction) to either radiation dose. Yeasts were the most resistant followed by inherent lactic acid bacteria; their reductions on the trimmings were radiation dose-dependent. Residual effects of irradiation were noted against enterococci, but not against gram-negatives which died off fast during fermentation even in non-irradiated samples. Growth of the starter bacteria, Lactobacillus pentosus and Staphylococcus carnosus, inoculated in the sausage batters post-irradiation was unaffected by the 2 or 4kGy pre-treatment of the trimmings. Irradiation had little or no effect at the end of ripening period (28 days) on pH, moisture content and color (parameters L(∗), a(∗), and b(∗)). Changes in TBA values were small but statistically significant with irradiated samples having higher TBA values than control samples.

Use of ionizing radiation doses of 2 and 4kGy to control Listeria spp. and Escherichia coli O157:H7 on frozen meat trimmings used for dry fermented sausage production.

This study evaluated survival of Listeria spp. (four-strain mixture of Listeria innocua plus a non-virulent Listeria monocytogenes strain) and Escherichia coli O157:H7 strain ATCC 43888 during fermentation and ripening of Greek dry sausages formulated from meat and pork fat trimmings previously inoculated with ca. 6logcfug(-1) of the target bacteria and then irradiated in frozen (-25°C) blocks at doses of 0 (control), 2 or 4kGy. Irradiation of the trimmings at 2kGy reduced initial contamination of the sausage batter with Listeria and E. coli O157:H7 by 1.3 and 2.0 logcfug(-1), respectively, while the corresponding reductions at 4kGy were 2.4 and 5.5 logcfug(-1), respectively. In fact, E. coli O157:H7 was eliminated by 4kGy at formulation (day 0) as compared to 7 and 21 days of ripening in samples treated at 2 and 0kGy, respectively. Despite the fact that irradiation assisted in faster declines of listeriae during fermentation, these bacteria showed a strong tailing during ripening, which was more pronounced in sausages irradiated at 4kGy. As a consequence, survival of Listeria in 28-day sausages irradiated at 2 or 4kGy was ca. 2 logcfug(-1) and similar (P>0.05) to that in non-irradiated samples. Irradiation showed promise for controlling E. coli O157:H7 and, to a lesser extent, L. monocytogenes in fermented sausages.

The spoilage microflora of cured, cooked turkey breasts prepared commercially with or without smoking.

Lactobacillus sakei subsp. carnosus was predominant in the spoilage flora of sliced, vacuum-packed, smoked, oven-cooked turkey breast fillets which developed mild, sour spoilage flavors after 4 weeks storage at 4 degrees C. In contrast, Leuconostoc mesenteroides subsp. mesenteroides predominated in the spoilage flora of sliced, vacuum-packed, unsmoked, boiled turkey breast fillets from the same plant which were also stored at 4 degrees C. The spoilage flora of the unsmoked breasts grew faster than that of the smoked breasts and was more diverse. Lactobacillus sakei, Weissella viridescens and an atypical group of leuconostoc-like bacteria were also members of the unsmoked turkey breasts flora. Consequently, the unsmoked breasts spoiled after 2 weeks at 4 degrees C: the packs swelled and the meat developed strong sour odors and flavors and abundant slime. Except for the unidentified leuconostocs, which apparently survived boiling of the unsmoked turkey, all the spoilage organisms contaminated the meats during the slicing and vacuum packaging operations. From their biochemical reactions and cellular fatty acid profiles, the atypical leuconostocs were more closely related to Leuconostoc carnosum than W. viridescens. Carnobacteria and Brochothrix thermosphacta were present in relatively large numbers on the raw turkey, but were not numerous in the spoilage flora of the cooked, vacuum-packed meat products.

Storage of poultry meat under modified atmospheres or vacuum packs: possible role of microbial metabolites as indicator of spoilage.

The effect of carbon dioxide (100%), nitrogen (100%), carbon dioxide/oxygen (20%:80%) or vacuum pack at 3 and 10 degrees C was studied on the microbial flora, in skinless poultry breast fillets or thigh meat. Lactic acid bacteria and Brochothrix thermosphacta were the predominant organisms in samples stored in vacuum packs, carbon dioxide and nitrogen. Pseudomonads grew only in oxygen/carbon dioxide packaging systems. The concentration of lactate diminished in both thigh and breast meat during storage at 3 and 10 degrees C. This decrease was more pronounced in thigh meat stored under 20%:80% carbon dioxide/oxygen. Acetate increased to varying degrees in all samples regardless of the storage conditions.

Evaluation of the extent and type of bacterial contamination at different stages of processing of cooked ham.

In an attempt to determine the composition and origin of the spoilage flora of refrigerated vacuum-packed cooked ham, the changes in microbial numbers and types were followed along the processing line. Results revealed Lactobacillus sake and Leuconostoc mesenteroides ssp. mesenteroides as the major causative agents of spoilage of sliced ham stored at 4 degrees C and 12 degrees C, due to recontamination in the cutting room. On the contrary, the progressive deterioration of whole ham under the same storage conditions was associated with a non-identifiable group of leuconostoc-like bacteria. Except for lactic acid bacteria, no other organism grew in vacuum packs of either sliced or whole ham. Although atypical leuconostocs could not be detected among isolates recovered from freshly produced whole ham, they appeared to survive cooking and proliferate during storage. Neither these organisms however, nor Lact. sake and Leuc. mesenteroides were important in curing and tumbling as carnobacteria, mainly Carnobacterium divergens, and Brochothrix thermosphacta dominated at this stage. A progressive inversion of the ham microflora from mostly Gram-negative at the beginning of processing to highly Gram-positive prior to cooking was noted. Listeria monocytogenes cross-contaminated ham during tumbling. However, the pathogen was always absent from the vacuum-packed product provided that heating to a core temperature of 70 degrees C occurred and recontamination during slicing and packing was prevented. The percentage distribution of different species of lactic acid bacteria as well as the uncommon phenotypic characteristics of some strains were discussed.

Multiple systems organ failure from organophosphate poisoning.

A 68-year-old man was admitted to an intensive care unit after a suicidal ingestion of dimethoate with organophosphate poisoning. Despite temporary improvement, the patient's condition progressively deteriorated with the development of adult respiratory distress syndrome and acute renal failure. Hemodynamic measurements substantiated the evidence of non cardiogenic pulmonary edema, while renal indices the presence of acute tubular necrosis. Despite vigorous organ specific support the patient died on the 12th hospital day. An autopsy confirmed the presence of adult respiratory distress syndrome and acute tubular necrosis. Organophosphate poison can be added to the list of toxins that caused adult respiratory distress syndrome and acute tubular necrosis and provoked the development of multiple systems organ failure.