scholarly journals Growth of Listeria monocytogenes in Thawed Frozen Foods

2017 ◽  
Vol 80 (3) ◽  
pp. 447-453 ◽  
Author(s):  
Ai Kataoka ◽  
Hua Wang ◽  
Philip H. Elliott ◽  
Richard C. Whiting ◽  
Melinda M. Hayman
Keyword(s):  
Growth Rate ◽  
Listeria Monocytogenes ◽  
Growth Rates ◽  
Storage Temperature ◽  
Growth Parameters ◽  
Quadratic Model ◽  
Lag Phase ◽  
Frozen Foods ◽  
Phase Duration ◽  
Primary Model

ABSTRACT The growth characteristics of Listeria monocytogenes inoculated onto frozen foods (corn, green peas, crabmeat, and shrimp) and thawed by being stored at 4, 8, 12, and 20°C were investigated. The growth parameters, lag-phase duration (LPD) and exponential growth rate (EGR), were determined by using a two-phase linear growth model as a primary model and a square root model for EGR and a quadratic model for LPD as secondary models, based on the growth data. The EGR model predictions were compared with growth rates obtained from the USDA Pathogen Modeling Program, calculated with similar pH, salt percentage, and NaNO2 parameters, at all storage temperatures. The results showed that L. monocytogenes grew well in all food types, with the growth rate increasing with storage temperature. Predicted EGRs for all food types demonstrated the significance of storage temperature and similar growth rates among four food types. The predicted EGRs showed slightly slower rate compared with the values from the U.S. Department of Agriculture Pathogen Modeling Program. LPD could not be accurately predicted, possibly because there were not enough sampling points. These data established by using real food samples demonstrated that L. monocytogenes can initiate growth without a prolonged lag phase even at refrigeration temperature (4°C), and the predictive models derived from this study can be useful for developing proper handling guidelines for thawed frozen foods during production and storage.

scholarly journals Prediction of growth kinetics of Pseudomonas spp. in meat products under isothermal and non-isothermal storage conditions

2021 ◽  
Vol 7 (3) ◽  
pp. 194-202
Author(s):  
Fatih Tarlak
Keyword(s):  
Goodness Of Fit ◽  
Storage Temperature ◽  
Food Products ◽  
Storage Conditions ◽  
Chicken Meat ◽  
Lag Phase ◽  
Phase Duration ◽  
Pseudomonas Spp ◽  
Primary Model ◽  
One Step

The main objective of the present study was to develop and validate a new alternative modelling method to predict the shelf-life of food products under non-isothermal storage conditions. The bacterial growth data of the Pseudomonas spp. was extracted from published studies conducted for aerobically-stored fish, pork and chicken meat and described with two-step and one-step modelling approaches employing different primary models (the modified Gompertz, logistic, Baranyi and Huang models) under isothermal storage temperatures. Temperature dependent kinetic parameters (maximum specific growth rate ‘µmax’ and lag phase duration ‘λ’) were described as a function of storage temperature via the Ratkowsky model integrated with each primary model. The Huang model based on the one-step modelling approach yielded the best goodness of fit results (RMSE = 0.451 and adjusted-R2 = 0.942) for all food products at isothermal storage conditions, therefore, was also used to check it’s the prediction capability under non-isothermal storage conditions. The differential form of the Huang model provided satisfactorily statistical indexes (1.075 > Bf > 1.014 and 1.080 > Af > 1.047) indicating reliably being able to use to describe the growth behaviour of Pseudomonas spp. in fish, pork and chicken meat subjected to non-isothermal storage conditions.

A Predictive Model for the Growth of Listeria monocytogenes in Commercial Blue Crab (Callinectes sapidus)

2017 ◽  
Vol 80 (11) ◽  
pp. 1872-1876
Author(s):  
Salina Parveen ◽  
Channel White ◽  
Mark L. Tamplin
Keyword(s):  
Listeria Monocytogenes ◽  
Blue Crab ◽  
Callinectes Sapidus ◽  
Lag Phase ◽  
Published Data ◽  
Predictive Tool ◽  
Phase Duration ◽  
Primary Model ◽  
Increasing Temperature ◽  
Crab Meat

ABSTRACT During the processing and handling of commercial blue crab (Callinectes sapidus), Listeria monocytogenes can potentially contaminate cooked meat and grow to hazardous levels. To manage this risk, predictive models are useful tools for designing and implementing preventive controls; however, no model specific for blue crab meat has been published or evaluated. In this study, a cocktail of L. monocytogenes strains was added to pasteurized blue crab meat, which was incubated at storage temperatures from 0 to 35°C. At selected time intervals, L. monocytogenes was enumerated by direct plating onto modified Oxford agar. A primary model was fitted to kinetic data to estimate the lag-phase duration (LPD) and growth rate (GR). Listeria monocytogenes replicated from 0 to 35°C, with GR ranging from 0.004 to 0.518 log CFU/h. Overall, the LPD decreased with increasing temperature, displaying a maximum value of 187 h at 0°C; however, this trend was not consistent. The LPD was not detected at 10°C, and it occurred inconsistently from trial to trial. A secondary GR model (R2 = 0.9892) for pasteurized crab meat was compared with the L. monocytogenes GR in fresh crab meat, demonstrating bias and accuracy factors of 0.98 and 1.36, respectively. The model estimates varied from other published data and models, especially at temperatures ≥5°C, supporting the need for a specific predictive tool for temperature deviations.

scholarly journals Omnibus Modeling of Listeria monocytogenes Growth Rates at Low Temperatures

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1099
Author(s):  
Vincenzo Pennone ◽  
Ursula Gonzales Barron ◽  
Kevin Hunt ◽  
Vasco Cadavez ◽  
Olivia McAuliffe ◽  
...  
Keyword(s):  
Growth Rate ◽  
Listeria Monocytogenes ◽  
Case Fatality ◽  
Second Order ◽  
Lag Phase ◽  
Model Parameters ◽  
Growth Data ◽  
Temperature Growth ◽  
First Order ◽  
Primary Model

Listeria monocytogenes is a pathogen of considerable public health importance with a high case fatality. L. monocytogenes can grow at refrigeration temperatures and is of particular concern for ready-to-eat foods that require refrigeration. There is substantial interest in conducting and modeling shelf-life studies on L. monocytogenes, especially relating to storage temperature. Growth model parameters are generally estimated from constant-temperature growth experiments. Traditionally, first-order and second-order modeling (or primary and secondary) of growth data has been done sequentially. However, omnibus modeling, using a mixed-effects nonlinear regression approach, can model a full dataset covering all experimental conditions in one step. This study compared omnibus modeling to conventional sequential first-order/second-order modeling of growth data for five strains of L. monocytogenes. The omnibus model coupled a Huang primary model for growth with secondary models for growth rate and lag phase duration. First-order modeling indicated there were small significant differences in growth rate depending on the strain at all temperatures. Omnibus modeling indicated smaller differences. Overall, there was broad agreement between the estimates of growth rate obtained by the first-order and omnibus modeling. Through an appropriate choice of fixed and random effects incorporated in the omnibus model, potential errors in a dataset from one environmental condition can be identified and explored.

scholarly journals Survival of Unstressed and Acid-, Cold-, and Starvation-Stress-AdaptedListeria monocytogenesin Ham Extract with Hops Beta Acids and Consumer Acceptability of HBA on Ready-to-Eat Ham

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Li Wang ◽  
Cangliang Shen
Keyword(s):  
Growth Rate ◽  
Listeria Monocytogenes ◽  
Sensory Evaluation ◽  
Growth Rates ◽  
Rapid Growth ◽  
Consumer Acceptability ◽  
Lag Phase ◽  
Starvation Stress ◽  
Hedonic Scale ◽  
Lag Phases

The efficacy of hops beta acids (HBA) against unstressed and stress-adaptedListeria monocytogenesin ham extract and the consumers’ acceptability of HBA on ready-to-eat (RTE) hams were investigated. Unstressed or acid-, cold-, or starvation-stress-adaptedL. monocytogeneswas inoculated (1.3–1.5 log CFU/mL) into 10% ham extract, without (control) or with HBA (4.44 or 10.0 µg/mL). Survival/growth of the pathogen during storage (7.2°C, 26 days) was monitored periodically. Sensory evaluation (30 participants, 9-point hedonic scale) was performed with hams dipped into 0.05, 0.11, and 0.23% HBA solution. Ham extracts without HBA supported rapid growth of unstressed and stress-adapted cells with growth rates of 0.39–0.71 log CFU/mL/day and lag phases of 0–3.26 days. HBA inhibited growth of unstressedL. monocytogenesby slowing (P<0.05) growth rate (0.24–0.29 log CFU/mL/day) and increasing (P<0.05) length of the lag phase (3.49–12.98 days) compared to control. Acid-, cold-, or starvation-stress-adapted cells showed cross protection against HBA with greater (P<0.05) growth rates (0.44–0.66 log CFU/mL/day) and similar or shorter lag phases (0–5.44 days) than unstressed cells. HBA did not (P>0.05) affect sensory attributes of RTE ham. These results are useful for RTE meat processors to develop operational protocols using HBA to controlL. monocytogenes.

Influence of Different Histories of the Inoculum on Lag Phase and Growth of Listeria monocytogenes in Meat Models

2006 ◽  
Vol 69 (3) ◽  
pp. 532-541 ◽  
Author(s):  
TOMAS JACOBSEN ◽  
ANETTE GRANLY KOCH
Keyword(s):  
Growth Rate ◽  
Listeria Monocytogenes ◽  
Salt Concentration ◽  
Biofilm Formation ◽  
Meat Products ◽  
Lag Phase ◽  
Modified Atmosphere ◽  
Phase Duration ◽  
History Of ◽  
Series Of Experiments

The aim of this study was to determine the effect of history of inoculum and preservatives on the lag phase and growth rate of Listeria monocytogenes strains in meat products packaged under modified atmosphere conditions. Inocula with different histories were added to meat models, and growth rate and lag phase of two strains of L. monocytogenes were measured at 5 and 10°C. The meat model stored at 10°C contained sodium lactate, but the model stored at 5°C did not. The five different histories of the inocula included cold propagation, biofilm formation, and starvation. The lag phase ranged from 1 to 10 days and was affected by the history of the inoculum, whereas the growth rate was constant except for one combination of history of inoculum and strain, where growth did not start during the incubation period. In a second series of experiments, the growth rate and lag phase of the two Listeria strains and the effects of two different histories of inoculum were tested in meat models with pH 5.7 or 6.5 and increasing amounts of NaCl. The growth rate depended on salt concentration, bacterial strain, and pH, whereas lag phase duration depended on history of inoculum, salt concentration, and pH. The lag phase duration was highly dependent on the history of the inoculum, and higher amounts of preservative (NaCl) made these effects even more noticeable. The results of this study underline the importance of the effects of the history of the inoculum on lag phase duration and could be used to predict lag phase in industrial meat products.

Effects of Lactic Acid on the Growth Characteristics of Listeria monocytogenes on Cooked Ham Surfaces†

2012 ◽  
Vol 75 (8) ◽  
pp. 1404-1410 ◽  
Author(s):  
CHENG-AN HWANG ◽  
LIHAN HUANG ◽  
SHIOWSHUH SHEEN ◽  
VIJAY JUNEJA
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Storage Temperature ◽  
Meat Products ◽  
Growth Characteristics ◽  
Lag Phase ◽  
Phase Duration ◽  
Cooked Ham ◽  
Root Model ◽  
Significant Extension

The surfaces of ready-to-eat meats are susceptible to postprocessing contamination by Listeria monocytogenes. This study examined and modeled the growth characteristics of L. monocytogenes on cooked ham treated with lactic acid solutions (LA). Cooked ham was inoculated with L. monocytogenes (ca. 103 CFU/g), immersed in 0, 0.5, 0.75, 1.0, 1.25, 1.5, and 2.0% LA for 30 min, vacuum packaged, and stored at 4, 8, 12, and 16°C. LA immersion resulted in &lt;0.7 log CFU/g immediate reduction of L. monocytogenes on ham surfaces, indicating the immersion alone was not sufficient for reducing L. monocytogenes. During storage, no growth of L. monocytogenes occurred on ham treated with 1.5% LA at 4 and 8°C and with 2% LA at all storage temperatures. LA treatments extended the lag-phase duration (LPD) of L. monocytogenes and reduced the growth rate (GR) from 0.21 log CFU/day in untreated ham to 0.13 to 0.06 log CFU/day on ham treated with 0.5 to 1.25% LA at 4°C, whereas the GR was reduced from 0.57 log CFU/day to 0.40 to 0.12 log CFU/day at 8°C. A significant extension of the LPD and reduction of the GR of L. monocytogenes occurred on ham treated with &gt;1.25% LA. The LPD and GR as a function of LA concentration and storage temperature can be satisfactorily described by a polynomial or expanded square-root model. Results from this study indicate that immersion treatments with &gt;1.5% LA for 30 min may be used to control the growth of L. monocytogenes on cooked meat, and the models would be useful for selecting LA immersion treatments for meat products to achieve desired product safety.

Effect of Salt, Smoke Compound, and Storage Temperature on the Growth of Listeria monocytogenes in Simulated Smoked Salmon†

2007 ◽  
Vol 70 (10) ◽  
pp. 2321-2328 ◽  
Author(s):  
CHENG-AN HWANG
Keyword(s):  
Listeria Monocytogenes ◽  
Storage Temperature ◽  
Control Measures ◽  
Lag Phase ◽  
Phase Duration ◽  
Liquid Smoke ◽  
Smoked Salmon ◽  
And Storage ◽  
Storage Temperatures ◽  
Maximum Population Density

Smoked salmon can be contaminated with Listeria monocytogenes. It is important to identify the factors that are capable of controlling the growth of L. monocytogenes in smoked salmon so that control measures can be developed. The objective of this study was to determine the effect of salt, a smoke compound, storage temperature, and their interactions on L. monocytogenes in simulated smoked salmon. A six-strain mixture of L. monocytogenes (102 to 103 CFU/g) was inoculated into minced, cooked salmon containing 0 to 10% NaCl and 0 to 0.4% liquid smoke (0 to 34 ppm of phenol), and the samples were stored at temperatures from 0 to 25°C. Lag-phase duration (LPD; hour), growth rate (GR; log CFU per hour), and maximum population density (MPD; log CFU per gram) of L. monocytogenes in salmon, as affected by the concentrations of salt and phenol, storage temperature, and their interactions, were analyzed. Results showed that L. monocytogenes was able to grow in salmon containing the concentrations of salt and phenol commonly found in smoked salmon at the prevailing storage temperatures. The growth of L. monocytogenes was affected significantly (P &lt; 0.05) by salt, phenol, storage temperature, and their interactions. As expected, higher concentrations of salt or lower storage temperatures extended the LPD and reduced the GR. Higher concentrations of phenol extended the LPD of L. monocytogenes, particularly at lower storage temperatures. However, its effect on reducing the GR of L. monocytogenes was observed only at higher salt concentrations (&gt;6%) at refrigerated and mild abuse temperatures (&lt;10°C). The MPD, which generally reached 7 to 8 log CFU/g in salmon that supported L. monocytogenes growth, was not affected by the salt, phenol, and storage temperature. Two models were developed to describe the LPD and GR of L. monocytogenes in salmon containing 0 to 8% salt, 0 to 34 ppm of phenol, and storage temperatures of 4 to 25°C. The data and models obtained from this study would be useful for estimating the behavior of L. monocytogenes in smoked salmon.

scholarly journals Modeling the Lag Time of Listeria monocytogenes from Viable Count Enumeration and Optical Density Data

2002 ◽  
Vol 68 (12) ◽  
pp. 5816-5825 ◽  
Author(s):  
F. Baty ◽  
J. P. Flandrois ◽  
M. L. Delignette-Muller
Keyword(s):  
Listeria Monocytogenes ◽  
Optical Density ◽  
Growth Parameters ◽  
Growth Models ◽  
Growth Parameter ◽  
Viable Count ◽  
Linear Increase ◽  
Lag Phase ◽  
Parameter Estimates ◽  
Phase Duration

ABSTRACT The following two factors significantly influence estimates of the maximum specific growth rate (μmax) and the lag-phase duration (λ): (i) the technique used to monitor bacterial growth and (ii) the model fitted to estimate parameters. In this study, nine strains of Listeria monocytogenes were monitored simultaneously by optical density (OD) analysis and by viable count enumeration (VCE) analysis. Four usual growth models were fitted to our data, and estimates of growth parameters were compared from one model to another and from one monitoring technique to another. Our results show that growth parameter estimates depended on the model used to fit data, whereas there were no systematic variations in the estimates of μmax and λ when the estimates were based on OD data instead of VCE data. By studying the evolution of OD and VCE simultaneously, we found that while log OD/VCE remained constant for some of our experiments, a visible linear increase occurred during the lag phase for other experiments. We developed a global model that fits both OD and VCE data. This model enabled us to detect for some of our strains an increase in OD during the lag phase. If not taken into account, this phenomenon may lead to an underestimate of λ.

scholarly journals Prevalence and growth dynamics of enterotoxinogenic Staphylococcus aureus isolates in Slovakian dairy products 

2014 ◽  
Vol 32 (No. 4) ◽  
pp. 337-341 ◽  
Author(s):  
A. Medveďová ◽  
A. Studeničová ◽  
Ľ. Valík ◽  
Z. Horváthová
Keyword(s):  
Staphylococcus Aureus ◽  
Growth Rate ◽  
Dairy Products ◽  
Growth Analysis ◽  
Growth Parameters ◽  
Growth Dynamics ◽  
Lag Phase ◽  
Phase Duration ◽  
Global Databases ◽  
High Degree

We investigated the prevalence of enterotoxigenic S. aureus in the Slovakian dairy products and compared the reliability of different routine methods of identification. Out of 64 isolates, 44% were confirmed as S. aureus. There was only a little correlation in the confirmation by API Staph, VIT-Staphylococcus, and PCR detection. The PCR results revealed that 32% of S. aureus isolates possessed the selected gene for SEs enterotoxins (SEA-SEE), with sea as the most predominant gene. Neither seb nor sed genes were found throughout the collection. Additionally, the growth analysis of the isolates was performed in milk at 15&deg;C. The growth parameters were very close to one another and were also compared with the data described in the global databases. These results provided evidence that the growth rate and lag phase duration can be determined with a high degree of reproducibility without regardless of the strain origin.

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