Recovery of heat-injured Listeria innocua

Miller, Fátima A.; Brandão, Teresa R. S.; Teixeira, Paula; Silva, Cristina L. M.

doi:10.1016/j.ijfoodmicro.2006.04.013

Cited by 53 publications

(42 citation statements)

References 18 publications

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“…In our work, the microbial inactivation parameters commonly used in food technology, D and z values, were comparable to those obtained by other authors under similar conditions (4,5,11,12,15,23) Variability in D values has been analyzed extensively by van Asselt and Zwietering (28), who compared 4,066 D values for pathogens and observed that most factors reported to affect the D value have an influence that is less than the variability of all published D values.…”

Section: Discussionsupporting

confidence: 88%

Analysis of the Variability in the Number of Viable Bacteria after Mild Heat Treatment of Food

Aguirre

Rodríguez

et al. 2009

Appl Environ Microbiol

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Variability in the numbers of bacteria remaining in saline solution and whole milk following mild heat treatment has been studied with Listeria innocua, Enterococcus faecalis, Salmonella enterica serovar Enteritidis, and Pseudomonas fluorescens. As expected, the most heat-resistant bacterium was E. faecalis, while P. fluorescens was the least heat resistant, and all bacteria showed greater thermal resistance in whole milk than in saline solution. Despite the differences in the inactivation kinetics of these bacteria in different media, the variability in the final number of bacteria was affected neither by the species nor by the heating substrate, but it did depend on the intensity of the heat treatment. The more severe the heat treatment was, the lower the average number of surviving bacteria but the greater the variability. Our results indicated that the inactivation times for the cells within a population are not identically distributed random variables and that, therefore, the population includes subpopulations of cells with different distributions for the heat resistance parameters. A linear relationship between the variability of the log of the final bacterial concentration and the logarithmic reduction in the size of the bacterial population was found.The safety and quality of many foods, such as minimally processed foods and some ready-to-eat products, are affected by a combination of multiple sublethal stresses due to processing and storage conditions (17, 32). The use of mild preservative processes instead of harsher ones affects the microbiological risk. It is therefore important to identify potential hazards and to perform accurate quantitative microbial risk assessments including probabilistic modeling approaches (17).It is unlikely that food products are contaminated by one unique bacterial strain or species. In fact, even cells from a pure culture derived from one cell are not necessarily identical (25). Nauta (16) differentiated between uncertainty, which is due to the lack of perfect knowledge about a parameter and which is reducible by further measurements, and variability, which reflects the true variability of a population and is therefore irreducible. He showed the importance of both parameters in quantitative microbial risk assessment models. The estimation of variability usually refers to the variation in the responses of the individual cells within the population, which may be homogeneous or heterogeneous. In a homogeneous population, the heat resistance parameters of the individual cells are identically distributed random variables. Heterogeneous populations include subpopulations of cells with different distributions for the heat resistance parameters. The heterogeneity of the individual cells or spores within a population is the most accepted explanation for the tails of inactivation curves (1, 30) and unexpected increases in the variability of the number of survivors after heat treatments (7,8,30).The microbial concentration in a food product at a given time is affected by the initial...

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Section: Discussionsupporting

confidence: 88%

Analysis of the Variability in the Number of Viable Bacteria after Mild Heat Treatment of Food

Aguirre

Rodríguez

et al. 2009

Appl Environ Microbiol

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“…The ability of selective enrichment broth to resuscitate temperature-, preservative-, salt-, and acid-stressed cells (1,3,33,36) encountered during food processing, storage, or sanitization is critical for detection. It is also well known that injured cells can cause an improper estimation of the decimal reduction time (D value) and z value (temperature required to change the D value to transverse by 1 log) during thermal processing (41) and, most importantly, that the injured pathogens can revive and grow under favorable conditions (9). We have demonstrated that SEL allowed the recovery of acid (pH 5.5)-and temperature (4°C)-stressed cells and that, overall, the recovery rates were comparable to those in nonselective TSBYE broth (Table 5).…”

Section: Discussionmentioning

confidence: 99%

SEL, a Selective Enrichment Broth for Simultaneous Growth of Salmonella enterica , Escherichia coli O157:H7, and Listeria monocytogenes

Kim

Bhunia

2008

Appl Environ Microbiol

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Multipathogen detection on a single-assay platform not only reduces the cost for testing but also provides data on the presence of pathogens in a single experiment. To achieve this detection, a multipathogen selective enrichment medium is essential to allow the concurrent growth of pathogens. SEL broth was formulated to allow the simultaneous growth of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes. The results were compared to those obtained with the respective individual selective enrichment broths, RappaportVassiliadis (RV) for S. enterica, modified E. coli broth with 20 mg of novobiocin/liter for E. coli O157:H7, and Fraser broth for L. monocytogenes, and a currently used universal preenrichment broth (UPB). The growth of each pathogen in SEL inoculated at 10 1 or 10 3 CFU/ml was superior to that in the respective individual enrichment broth, except in the case of RV, in which Salmonella cells inoculated at both concentrations grew equally well. In mixed-culture experiments with cells of the three species present in equal concentrations or at a 1:10:1,000 ratio, the overall growth was proportional to the initial inoculation levels; however, the growth of L. monocytogenes was markedly suppressed when cells of this species were present at lower concentrations than those of the other two species. Further, SEL was able to resuscitate acid-and cold-stressed cells, and recovery was comparable to that in nonselective tryptic soy broth containing 6% yeast extract but superior to that in the respective individual selective broths. SEL promoted the growth of all three pathogens in a mixture in ready-to-eat salami and in turkey meat samples. Moreover, each pathogen was readily detected by a pathogen-specific immunochromatographic lateral-flow or multiplex PCR assay. Even though the growth of each pathogen in SEL was comparable to that in UPB, SEL inhibited greater numbers of nontarget organisms than did UPB. In summary, SEL was demonstrated to be a promising new multiplex selective enrichment broth for the detection of the three most prominent food-borne pathogens by antibody-or nucleic acid-based methods.

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“…Samples were removed from the stirred TSBYE at different time intervals and immediately placed in a mixture of ice-water. Samples were serially diluted and plated in duplicate onto three different media: (i) TSAYE, (ii) TSAYE supplemented with 5% (w/v) sodium chloride -TSAYE + NaCl and (iii) Palcam Agar plus selective supplement (Miller, Brandao, Teixeira, & Silva, 2006). Plates were incubated at 30°C…”

Section: Log Reduction Experiments In Brothmentioning

confidence: 99%

nfluences of physicochemical stresses on injury and inactivation behaviour of Listeria innocua

Miller

Ramos

Gil

et al. 2017

IJFS

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Many minimally processed foods depend on a combination of inhibitory factors to reduce the hazard of foodborne illness. Therefore, inactivation of Listeria innocua was studied according to a 2 4 factorial experiment designed to draw conclusions about temperature (52.5°C and 65.0°C), pH (4.5 and 7.5), water activity (aw=0.95 and 0.99) and solute type (NaCl and glycerol) effects. Three different recovery media were used to assess injured cells. Survival data were fitted with a Gompertz-based model and kinetic parameters (shoulder, maximum inactivation rate -kmax, and tail) were estimated. Results showed that shoulder was affected by temperature, pH and combined effects; kmax was influenced by all factors and their combinations; and tail was affected by aw, temperature and aw/pH combination. Results demonstrated the potential occurrence of microbial cross-protection survival techniques between the various stresses, e.g. heat and osmolarity. Indeed, this work clearly established that, to avoid hazards, Listeria inactivation must be evaluated with a maximum of environmental factors that undergo alterations. Only thus, appropriate food preservation treatments can be developed and consequently, the safety of food products can be assured.

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Recovery of heat-injured Listeria innocua

Cited by 53 publications

References 18 publications

Analysis of the Variability in the Number of Viable Bacteria after Mild Heat Treatment of Food

Analysis of the Variability in the Number of Viable Bacteria after Mild Heat Treatment of Food

SEL, a Selective Enrichment Broth for Simultaneous Growth of Salmonella enterica , Escherichia coli O157:H7, and Listeria monocytogenes

nfluences of physicochemical stresses on injury and inactivation behaviour of Listeria innocua

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