摘要:

ABSTRACTThe use of mathematical modeling of microbiological behavior to predict and evaluate food safety or shelf life is receiving considerable interest. Researchers are attempting to use mathematical equations that incorporate such critical growth factors as pH, aw, and NaCl content to predict microbial growth and/or toxin production in order to replace traditional time‐intensive challenge studies. Predictive equations can be divided into probabilistic, regression, Arrhenius, and square root models. Models vary greatly in theory and complexity. Predictive models are used to monitor processes ranging from temperature during distribution to inventory control. They have been shown to be useful in product development and shelf‐life estimation when safety is not an issue. Most models are generated by regression analysis of data obtained from laboratory experiments. Statistically based models, even when conservatively derived, are not appropriate as the only criterion for evaluating food saf

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1994.tb00594.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThere is increased marketing of ready‐to‐eat nonrefrigerated snack foods which consist of meat or sausage products with low or intermediate moisture levels combined with high moisture food products, i.e., cheese products. Packaging the intermediate moisture meat in direct contact with a high moisture food might change the water activity (aw) of the products sufficiently to support growth of Staphylococcus aureus at contaminated interfaces. To evaluate this possibility, sterile sausage slices (aw= 0.60 to 0.82) were surface inoculated with log 2‐3 CFU/g of S. aureus, interfaced with processed cheese slices (aw= 0.94), vacuum packaged, and incubated at 19, 28, 37C and at cyclic temperature of 19–37–19C. S. aureus levels and water activities were determined weekly for 0 to 9 weeks. The awat the interface changed rapidly and reached an awthat supported S. aureus growth. Growth of S. aureus occurred under all test conditions when the samples were stored at 28 and 37C. At 19C storage S. aureus remained viable for the length of

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1994.tb00595.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTChanges during production and ripening in the microbial flora of 11 batches of Arzúa, a soft cheese made from raw cow's milk, were investigated. The following microbial groups were counted on the surface and interior of the cheese: total viable count (TVC), lactic acid bacteria (LAB), halotolerant flora, enterococci, proteolytic enterococci, staphylococci, Staphylococcus aureus, Enterobacteriaceae, faecal coliforms, molds, yeasts, Listeria spp. and (in milk) Brucella spp. pH and water activity were also determined. TVC and LAB were, generally, more than 9 log (cfu/g). Enterococci counts increased gradually, reaching values in excess of 6 log units. Halotolerant flora and staphylococci remained practically constant throughout ripening, at 6–8 and 5–7 log units, respectively. Maximum Enterobacteriaceae and faecal coliform counts exceeded 7 and 6 log units, respectively. Brucella spp. were not detected in any of the milk samples. Listeria spp. were detected in four batches, and Listeria monocytogenes in

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1994.tb00596.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTMeat acquires a characteristic microflora after slaughter and butchering. This normal microflora may be beneficial in that it occupies a niche that would otherwise permit unimpeded growth of potential pathogens. Lactic acid decontamination (LAD) is intended to eliminate pathogens but also affects the normal microflora. The immediate effect was studied by means of an in‐vitro model. Experiments using this model achieved a reduction in the mesophilicEnterobacteriaceaeon meat by 1 to 3 log10colony forming units and shifted the predominant microflora in the direction of Gram‐positive bacteria and yeasts. Colony counts were an unreliable indicator of LAD‐induced reductions in Gramnegative foodborne pathogens. Their reduction depended on the ratio of the more lactic acid resistant Gram‐positive bacteria to the more sensitive Gram‐negative bacteria. The rank order of lactic acid‐resistance of nonpathogens present on meat was yeasts = lactobacilli>psychrotrophic Gram‐positive bacteria>mesophilicEnterobacteriaceae.Psychrotrophic Gram‐negative bacteria were the

ISSN:0149-6085    

DOI:10.1111/j.1745-4565.1994.tb00597.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY