Characterization of damage on Listeria innocua surviving to pulsed light: Effect on growth, DNA and proteome.

The effect of pulsed light treatment on the lag phase and the maximum specific growth rate of Listeria innocua was determined in culture media at 7 °C. Fluences of 0.175, 0.

Effect of nitrate and nitrite on Listeria and selected spoilage bacteria inoculated in dry-cured ham.

The effect of nitrate and the combination of nitrate/nitrite on Listeria innocua (as surrogate of Listeria monocytogenes). And two selected spoilage microorganisms (Proteus vulgaris and Serratia liquefaciens) was studied in dry-cured ham. Hams were manufactured with different concentrations of curing agents: KNO (600 and 150mg/kg) alone or in combination with NaNO (600 and 150mg/kg).

Effect of storage temperature on the lag time of Geobacillus stearothermophilus individual spores.

The lag times (λ) of Geobacillus stearothermophilus single spores were studied at different storage temperatures ranging from 45 to 59 °C using the Bioscreen C method. A significant variability of λ was observed among individual spores at all temperatures tested. The storage temperature affected both the position and the spread of the λ distributions.

Towards lag phase of microbial populations at growth-limiting conditions: The role of the variability in the growth limits of individual cells.

The water activity (aw) growth limits of unheated and heat stressed Listeria monocytogenes individual cells were studied. The aw limits varied from 0.940 to 0.

Estimation of the growth kinetic parameters of Bacillus cereus spores as affected by pulsed light treatment.

Quantitative microbial risk assessment requires the knowledge of the effect of food preservation technologies on the growth parameters of the survivors of the treatment. This is of special interest in the case of the new non-thermal technologies that are being investigated for minimal processing of foods. This is a study on the effect of pulsed light technology (PL) on the lag phase of Bacillus cereus spores surviving the treatment and the maximum growth rate (μmax) of the survivors after germination.

Modeling the Listeria innocua micropopulation lag phase and its variability.

Listeria innocua micropopulation lag phase and its variability have been modeled as a function of growth temperature, intensity of heat stress, and the number of surviving cells initiating growth. Micropopulation lag phases were found to correlate negatively with inoculum size and growth temperature and positively with heat shock intensity. Validation of the models using experimental milk samples indicated that the average lag phase duration predicted is shorter and more variable than the observed, meaning that they should be considered safe for risk assessment.

A comparison of the effects of E-beam irradiation and heat treatment on the variability of Bacillus cereus inactivation and lag phase duration of surviving cells.

The effects of electron beam irradiation and heat treatments on the variability of inactivation of Bacillus cereus spores (CECT 131/ATCC 10876) and of the lag phase of single surviving cells have been studied. In general, dispersion in the number of survivors increased as the stress became more intense. A polynomial relationship was derived between the coefficient of variation of the survivor number and the inactivation achieved.

Effects of electron beam irradiation on the variability in survivor number and duration of lag phase of four food-borne organisms.

The effect of electron beam irradiation on microbial inactivation and duration of lag time of individual surviving cells of Listeria innocua, Enterococcus faecalis, Pseudomonas fluorescens and Salmonella Enteritidis has been studied. In addition, the data on variability in microbial inactivation and duration of lag phase for surviving microbes have been fitted by normal and gamma distributions, respectively. The standard deviations of survivor number and lag phase duration of individual cells were higher in irradiated batches than in non-irradiated ones.