PubMed · 7873328
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
1994. Special issue: Predictive modelling.. https://pubmed.ncbi.nlm.nih.gov/7873328/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Peptone (0.1%) solution containing 3% NaCl (PS) was a more suitable diluent than phosphate buffered saline (PBS) solution for the enumeration of Vibrio vulnificus in both broth cultures and oyster homogenates. PBS caused significant underestimation of the viable population of the species by plate counts on either selective or non-selective media. Dilution in PS is recommended in methods for the enumeration of V. vulnificus.
Heating at slowly rising temperatures is suspected to enhance thermotolerance in Listeria monocytogenes and, since anaerobic environments have been shown to facilitate resuscitation of heat-injured cells of this micro-organism, concern may arise about the possibility of L. monocytogenes surviving in minimally preserved products. The effect of rapid ( > 10 degrees C min-1) and slow (0.3 and 0.6 degrees C min-1) heating on survival of L. monocytogenes in sous vide cooked beef was therefore examined at mild processing temperatures of 56 degrees, 60 degrees and 64 degrees C. No statistically significant difference (P = 0.70) was observed between the tested heating regimes. Since the average pH of beef was low (5.6), and little or no effect was observed, a pH-dependency of heat shock-induced thermotolerance in L. monocytogenes is suggested to account for this result.
A modified Monod equation was successfully applied to describe the maximum specific growth rate of Listeria innocua in a broth model in the presence of various concentrations of sodium lactate or NaCl. The combined effects of temperature and pH were assessed by translating the parameters of the modified Monod equation mu(m), alpha, and p') as functions of pH and/or temperature. As a result, the area in which the growth rate could be predicted was extended to include as a variable not only the salt concentration but also pH and temperature. The number of parameters needed to describe the experimental data was thereby reduced from 48 to 4 (NaCl) and from 42 to 5 (sodium lactate). The decline in the goodness of fit that accompanied the reduction in the number of parameters was within statistically acceptable ranges. The resulting model was compared with a polynomial fit, and it was proposed that the former was more suitable for the purpose of this study. The broth model for sodium lactate was evaluated with Bologna-type sausages. Because of the "worst-case" design of the broth model, it was necessary to reestimate one or all parameters to obtain a good description of the growth rate of L. innocua in the meat product. However, the simplicity of the model and the practical usefulness of its parameters offer considerable prospects for its use in predictive microbiology.