Growth of Listeria monocytogenes in Different Retail Delicatessen Meats during Simulated Home Storage

2012 ◽  
Vol 75 (5) ◽  
pp. 896-905 ◽  
Author(s):  
LEI ZHANG ◽  
SCOTT R. MOOSEKIAN ◽  
EWEN C. D. TODD ◽  
ELLIOT T. RYSER
Keyword(s):  
Listeria Monocytogenes ◽  
Storage Temperature ◽  
The United States ◽  
Lag Phase ◽  
Product Formulation ◽  
Total Inhibition ◽  
Generation Times ◽  
Roast Beef ◽  
The Impact ◽  
And Storage

Delicatessen meats are reported to be the leading vehicle of foodborne listeriosis in the United States. Listeria monocytogenes can reach high numbers in these products during storage, and the growth rate is largely dictated by product formulation and storage temperature. To assess the impact of product age on Listeria growth, five commercial brands each of cured and uncured turkey breast, ham, and roast beef (three lots per brand) were sliced (approximately 25 g per slice) at the beginning of the shelf life, the midpoint, and the last allowable day of sale, surface inoculated with an eight-strain cocktail of L. monocytogenes (approximately 40 CFU/g), and then quantitatively examined for Listeria, lactic acid bacteria, and mesophilic aerobic bacteria during aerobic storage at 4, 7, or 10°C. As expected, L. monocytogenes grew faster in deli meats without rather than with Listeria inhibitors (lactate and/or diacetate) and at the highest storage temperature (10°C). Lag-phase durations for L. monocytogenes in deli meats with and without Listeria inhibitors were 9.21, 6.96, and 5.00 and 6.35, 3.30, and 2.19 days at 4, 7, and 10°C, respectively. Generation times for L. monocytogenes in deli meats with and without Listeria inhibitors were 1.59, 1.53, and 0.85 and 0.94, 0.50, and 0.36 at 4, 7, and 10°C, respectively. Maximum population densities for L. monocytogenes in deli meats with and without Listeria inhibitors were 5.26, 5.92, and 5.97 and 8.47, 8.96 and 9.34 log CFU/g at 4, 7, and 10°C, respectively. Although lactate and diacetate suppressed L. monocytogenes growth, the extent of inhibition differed, ranging from total inhibition in roast beef to only partial inhibition in ham and cured turkey. Listeria growth was also impacted by lot-to-lot variation in the concentrations of Listeria inhibitors, product pH, and background microflora. These data will be useful for developing recommendations for “best consumed by” dating for deli meats using a risk-based approach.

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 < 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 (>6%) at refrigerated and mild abuse temperatures (<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 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.

Quantitative Risk Assessment of Listeriosis-Associated Deaths Due to Listeria monocytogenes Contamination of Deli Meats Originating from Manufacture and Retail

2010 ◽  
Vol 73 (4) ◽  
pp. 620-630 ◽  
Author(s):  
ABANI K. PRADHAN ◽  
RENATA IVANEK ◽  
YRJÖ T. GRÖHN ◽  
ROBERT BUKOWSKI ◽  
IFIGENIA GEORNARAS ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Listeria Monocytogenes ◽  
Relative Risk ◽  
Storage Temperature ◽  
Control Strategies ◽  
Quantitative Risk Assessment ◽  
Sensitivity Analyses ◽  
Effective Control ◽  
Lag Phase ◽  
Reported Data

The objective of this study was to estimate the relative risk of listeriosis-associated deaths attributable to Listeria monocytogenes contamination in ham and turkey formulated without and with growth inhibitors (GIs). Two contamination scenarios were investigated: (i) prepackaged deli meats with contamination originating solely from manufacture at a frequency of 0.4% (based on reported data) and (ii) retail-sliced deli meats with contamination originating solely from retail at a frequency of 2.3% (based on reported data). Using a manufacture-to-consumption risk assessment with product-specific growth kinetic parameters (i.e., lag phase and exponential growth rate), reformulation with GIs was estimated to reduce human listeriosis deaths linked to ham and turkey by 2.8- and 9-fold, respectively, when contamination originated at manufacture and by 1.9- and 2.8-fold, respectively, for products contaminated at retail. Contamination originating at retail was estimated to account for 76 and 63% of listeriosis deaths caused by ham and turkey, respectively, when all products were formulated without GIs and for 83 and 84% of listeriosis deaths caused by ham and turkey, respectively, when all products were formulated with GIs. Sensitivity analyses indicated that storage temperature was the most important factor affecting the estimation of per annum relative risk. Scenario analyses suggested that reducing storage temperature in home refrigerators to consistently below 7°C would greatly reduce the risk of human listeriosis deaths, whereas reducing storage time appeared to be less effective. Overall, our data indicate a critical need for further development and implementation of effective control strategies to reduce L. monocytogenes contamination at the retail level.

scholarly journals Effect of Potassium Lactate and a Potassium Lactate–Sodium Diacetate Blend on Listeria monocytogenes Growth in Modified Atmosphere Packaged Sliced Ham

2007 ◽  
Vol 70 (10) ◽  
pp. 2297-2305 ◽  
Author(s):  
L. A. MELLEFONT ◽  
T. ROSS
Keyword(s):  
Listeria Monocytogenes ◽  
Organic Acid ◽  
Shelf Life ◽  
Storage Temperature ◽  
Modified Atmosphere ◽  
Acid Salt ◽  
Potassium Lactate ◽  
Sodium Diacetate ◽  
Potential Inhibitors ◽  
And Storage

Two commercially available organic acid salts, potassium lactate (PURASAL HiPure P) and a potassium lactate–sodium diacetate blend (PURASAL Opti.Form PD 4), were assessed as potential inhibitors of Listeria monocytogenes growth in modified atmosphere packaged (MAP) sliced ham in challenge studies. The influence of the initial inoculation level of L. monocytogenes (101 or 103 CFU g−1) and storage temperature (4 or 8°C) was also examined. The addition of either organic acid salt to MAP sliced ham strongly inhibited the growth of L. monocytogenes during the normal shelf life of the product under ideal refrigeration conditions (4°C) and even under abusive temperature conditions (i.e., 8°C). During the challenge studies and in the absence of either organic acid salt, L. monocytogenes numbers increased by 1,000-fold after 20 days at 8°C and 10-fold after 42 days at 4°C. Both organic acid salt treatments were found to be listeriostatic rather than listericidal. The addition of either organic acid salt to the MAP ham also reduced the growth of indigenous microflora, i.e., aerobic microflora and lactic acid bacteria. The influence of these compounds on the risk of listeriosis in relation to product shelf life is discussed.

Control of Listeria monocytogenes on Frankfurters with Antimicrobials in the Formulation and by Dipping in Organic Acid Solutions

2004 ◽  
Vol 67 (11) ◽  
pp. 2456-2464 ◽  
Author(s):  
I. M. BARMPALIA ◽  
I. GEORNARAS ◽  
K. E. BELK ◽  
J. A. SCANGA ◽  
P. A. KENDALL ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Organic Acid ◽  
The United States ◽  
Acid Solutions ◽  
Overall Acceptability ◽  
Bactericidal Effects ◽  
Yeasts And Molds ◽  
And Storage

The antilisterial activity of sodium lactate (SL) and sodium diacetate (SD) was evaluated in a frankfurter formulation and in combination with a dipping treatment into solutions of lactic acid or acetic acid after processing and inoculation. Pork frankfurters were formulated with 1.8% SL or 0.25% SD or combinations of 1.8% SL with 0.25 or 0.125% SD. After processing, frankfurters were inoculated (2 to 3 log CFU/cm2) with a 10-strain composite of Listeria monocytogenes and left undipped or were dipped (2 min) in 2.5% solutions of lactic acid or acetic acid (23 ± 2°C) before vacuum packaging and storage at 10°C for 40 days. Total microbial populations and L. monocytogenes, lactic acid bacteria, and yeasts and molds were enumerated during storage. Sensory evaluations also were carried out on frankfurters treated and/or formulated with effective antimicrobials. The combination of 1.8% SL with 0.25% SD provided complete inhibition of L. monocytogenes growth throughout storage. Dipping in lactic acid or acetic acid reduced initial populations by 0.7 to 2.1 log CFU/cm2, but log CFU/cm2. For samples containing single antimicrobials and dipped in lactic acid or acetic acid, L. monocytogenes growth was completely inhibited or reduced over 12 and 28 days, respectively, whereas final populations were lower (P < 0.05) than those in undipped samples of the same formulations. Bactericidal effects during storage (reductions of 0.6 to 1.0 log CFU/cm2 over 28 to 40 days) were observed in frankfurters containing combinations of SL and SD that were dipped in organic acid solutions. Inclusion of antimicrobials in the formulation and/or dipping the product into organic acid solutions did not affect (P > 0.05) the flavor and overall acceptability of products compared with controls. The results of this study may be valuable to meat processors as they seek approaches for meeting new regulatory requirements in the United States.

Effect of Equilibrated pH and Indigenous Spoilage Microorganisms on the Inhibition of Proteolytic Clostridium botulinum Toxin Production in Experimental Meals under Temperature Abuse

2017 ◽  
Vol 80 (8) ◽  
pp. 1252-1258 ◽  
Author(s):  
Max C. Golden ◽  
Brandon J. Wanless ◽  
Jairus R. D. David ◽  
D. Scott Lineback ◽  
Ryan J. Talley ◽  
...  
Keyword(s):  
Botulinum Toxin ◽  
Clostridium Botulinum ◽  
Storage Temperature ◽  
Phase 1 ◽  
Toxin Production ◽  
Brussels Sprouts ◽  
The Impact ◽  
And Storage ◽  
Spoilage Microorganisms ◽  
Toxin Formation

ABSTRACT Clostridium botulinum is a foreseeable biological hazard in prepared refrigerated meals that needs to be addressed in food safety plans. The objective of this study was to evaluate the effect of product composition and storage temperature on the inhibition of botulinum toxin formation in nine experimental meals (meat, vegetable, or carbohydrate based). Treatments were inoculated with proteolytic C. botulinum, vacuum packaged, cooked at 90°C for 10 min, and assayed for botulinum toxin in samples stored at 25°C for up to 96 h for phase 1, or at 25°C for 12 h and then transferred to 12.5°C for up to 12 and 6 weeks in phases 1 and 2, respectively. For phase 1, none of the treatments (equilibrated pH 5.8) supported toxin production when stored at 25°C for 48 h, but toxin production was observed in all treatments at 72 h. For the remaining experiments with storage at 12.5°C, toxin production was dependent on equilibrated pH, storage time, and growth of indigenous spoilage microorganisms. In phase 1, no gross spoilage and no botulinum toxin was detected for any treatment (pH ≤5.8) stored at 12.5°C for 12 weeks. In phase 2, gross spoilage varied by commodity, with the brussels sprouts meal with pH 6.5 showing the most rapid spoilage within 2 weeks and botulinum toxin detected at 5 and 6 weeks for the control and cultured celery juice treatments, respectively. In contrast, spoilage microbes decreased the pH of a pH 5.9 beef treatment by 1.0 unit, potentially inhibiting C. botulinum through 6 weeks at 12.5°C. None of the other treatments with pH 5.8 or below supported toxin production or spoilage. This study provides validation for preventive controls in refrigerated meals. These include equilibrated product pH and storage temperature and time to inhibit toxin formation by proteolytic C. botulinum, but the impact of indigenous microflora on safety and interpretation of challenge studies is also highlighted.

Inhibitory Activity of Colicin E1 against Listeria monocytogenes

2007 ◽  
Vol 70 (5) ◽  
pp. 1256-1262 ◽  
Author(s):  
BRENDA S. PATTON ◽  
JAMES S. DICKSON ◽  
STEVEN M. LONERGAN ◽  
SARA A. CUTLER ◽  
CHAD H. STAHL
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Inhibitory Activity ◽  
Storage Temperature ◽  
Strain Differences ◽  
Inoculum Concentration ◽  
Gram Negative ◽  
Initial Inoculum ◽  
Colicin E1 ◽  
And Storage

Colicins are gram-negative bacteriocins produced by and effective against Escherichia coli and related species. Colicin E1 (ColE1) is composed of three functional domains, which collectively have a pore-forming effect on targeted bacteria. ColE1 binding and translocation domains are highly specific in contrast to the pore-forming domain, implying that ColE1 could be broadly effective. In this study, the activity of ColE1 against Listeria monocytogenes was evaluated in broth and on surfaces of ready-to-eat products. Individual strains of L. monocytogenes were examined in broth containing ColE1 at 0, 0.1, 1, or 10 μg/ml. Although strain differences in sensitivity to ColE1 existed, growth was significantly reduced in all strains at doses as low as 0.1 μg/ml. Sterilized ham slices were submerged in a five-strain L. monocytogenes cocktail (either 7 or 4 log CFU/ml) and placed in vacuum packages containing 0, 1, 5, 10, 25, or 50 μg of ColE1. Ham slices were then stored at 4 or 10°C, and samples were removed and examined for L. monocytogenes after 1, 3, 7, and 14 days. Reduction of L. monocytogenes by ColE1 was dependent on initial inoculum concentration and storage temperature. For slices stored at 4°C, treatment with 25 μg reduced Listeria growth below detection limits for the slices inoculated with 4 log CFU/ml for the entire 14 days, whereas for the 7-log CFU/ml slices, growth was detected at 7 days postinoculation. For slices stored at 10°C, 10 μg/ml ColE1 significantly inhibited growth of L. monocytogenes for up to 3 days for both inoculation groups. These data indicate that ColE1 is highly effective against Listeria.

Impact of Plant Siting on Performance and Economics of Indirect Supercritical CO2 Coal Fired Power Plants

2021 ◽  
Author(s):  
Sandeep R. Pidaparti ◽  
Charles W. White ◽  
Nathan T. Weiland
Keyword(s):  
Supercritical Co2 ◽  
Optimization Design ◽  
Power Plants ◽  
Waste Heat ◽  
The United States ◽  
Attractive Alternative ◽  
Plant Design ◽  
Power Cycles ◽  
The Impact ◽  
And Storage

Abstract Indirect-fired supercritical CO2 (sCO2) power cycles are being explored as an attractive alternative to steam Rankine cycles for a variety of heat sources including fossil, concentrated solar power (CSP), nuclear, waste heat, etc. Due to the near-ambient CO2 critical temperature of 31°C, the effects of ambient temperature on sCO2 power cycles performance are expected to be more significant than for steam Rankine cycles. This study presents the impact of plant siting on the performance and economics of coal-fired utility scale power plants based on indirect sCO2 power cycles with carbon capture and storage (CCS). Four different plant sites across the United States have been selected for investigation: Chicago, IL; Kemmerer, WY; Houston, TX; Knoxville, TN. For each plant site, local parameters such as design ambient conditions, coal type and prices, captured CO2 transportation and storage (T&S) costs are considered for the techno-economic analyses (TEA). To determine the optimum plant design for each location, two power cycle configurations (recompression cycle, partial cooling cycle with reheat) and two cooling technologies (dry and adiabatic cooling) are examined. The optimization was conducted using automated derivative-free optimization (DFO) algorithms available under NETL’s Framework for Optimization and Quantification of Uncertainty and Sensitivity (FOQUS) platform. The optimization design variables include parameters such as turbine inlet temperatures and pressure, sCO2 cooler outlet temperatures, recuperators approach temperature and pressure drop etc. The study demonstrates the variability in optimal plant design for different ambient and fuel input conditions. The results will be used in future sCO2 technology market analyses.

Death of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in Garlic Butter as Affected by Storage Temperature

2002 ◽  
Vol 65 (12) ◽  
pp. 1976-1980 ◽  
Author(s):  
BARBARA B. ADLER ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Pathogenic Bacteria ◽  
Storage Time ◽  
Storage Temperature ◽  
Rapid Decline ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Pathogen Populations ◽  
And Storage

Garlic is known to have antimicrobial activity against several spoilage and pathogenic bacteria. However, the fate of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in garlic butter has not been reported. This study was undertaken to determine the viability of these organisms in garlic butter as affected by the type of raw minced garlic added to the butter, storage temperature, and storage time. Unsalted butter at 40°C was combined with raw minced jumbo, elephant, or small-cloved garlic at a 4:1 butter/garlic ratio (wt/wt), inoculated with mixed-strain suspensions of Salmonella, E. coli O157:H7, or L. monocytogenes, and stored at 4.4, 21, or 37°C for up to 48 h. All pathogens retained their viability at 4.4°C, regardless of the presence of garlic. The addition of garlic to butter enhanced the rates of inactivation of all three pathogens at 21 and 37°C. The most rapid decline in pathogen populations was observed at 37°C. The inactivation of L. monocytogenes occurred more slowly than did that of Salmonella or E. coli O157:H7. The inactivation of Salmonella and L. monocytogenes was more rapid in jumbo garlic butter than in elephant or small-cloved garlic butter. It is concluded that Salmonella, E. coli O157:H7, and L. monocytogenes did not grow in unsalted butter, with or without garlic added (20%, wt/wt), when inoculated products were stored at 4.4, 21, and 37°C for up to 48 h.

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