Thermal Resistance of Listeria monocytogenes and Salmonella spp. in Liquid Egg White

1996 ◽  
Vol 59 (11) ◽  
pp. 1182-1186 ◽  
Author(s):  
M. S. PALUMBO ◽  
S. M. BEERS ◽  
S. BHADURI ◽  
S. A. PALUMBO
Keyword(s):  
Hydrogen Peroxide ◽  
Listeria Monocytogenes ◽  
Salmonella Enteritidis ◽  
Egg White ◽  
Heat Sensitivity ◽  
Salmonella Spp ◽  
Single Strain ◽  
Ph Values ◽  
D Values ◽  
Unit Reduction

Survival of a five-strain mixture of Listeria monocytogenes and a six-strain mixture of Salmonella enteritidis, S. typhimurium, and S. senftenberg (not 775W) in liquid egg white was determined by a submerged-vial technique at 51.5°C and 53.2°C with 0.875% added H2O2 and at 55.5°C, 56.6°C, and 57.7°C with no additions. Survival at a range of pH values at 56.6°C also was determined. Surviving bacteria were counted on tryptic soy agar and results expressed as D-values; log-unit reductions in counts in 3.5 min or 6.2 min were calculated from these D-values. Plate pasteurization of commercially broken egg white (pH 8.8) inoculated with a single strain of L. innocua or S. senftenberg also was performed. Heating under currently approved pasteurization conditions, 51.5°C for 3.5 min with hydrogen peroxide, 55.6°C for 6.2 min, or 56.7°C for 3.5 min, resulted in a less than 3-1og unit reduction of viable Salmonella spp. and a less than 0.5-1og unit reduction of L. monocytogenes. At 53.2°C with peroxide, plate pasteurization resulted in a 3.44-1og unit reduction of S. senftenberg in 3.5 min. At 57.7°C with no peroxide, the D-value for Salmonella spp. was 0.78 min when heated in submerged vials, and plate pasteurization reduced viable numbers by 3.64 log units in 3.5 min. Destruction of Listeria under these conditions was still less than 1 log unit. Variation in the pH of the egg white from 7.8 to 9.3 resulted in D-values for Salmonella spp. at 56.6°C of 3.60 min to 1.08 min, respectively. D-values for L. monocytogenes under these conditions ranged from 10.4 min at pH 7.8 to 20.9 min at pH 9.3. The reduced heat sensitivity of Salmonella spp. at lower pH values should be considered in reevaluating pasteurization procedures.

Thermal Resistance of Salmonella spp. and Listeria monocytogenes in Liquid Egg Yolk and Egg Yolk Products†

1995 ◽  
Vol 58 (9) ◽  
pp. 960-966 ◽  
Author(s):  
MARY S. PALUMBO ◽  
SHARON M. BEERS ◽  
SAUMYA BHADURI ◽  
SAMUEL A. PALUMBO
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Minimum Temperature ◽  
Salmonella Enteritidis ◽  
Egg Yolk ◽  
Salmonella Spp ◽  
Egg Products ◽  
D Values ◽  
Unit Reduction ◽  
D Value

The effectiveness of various pasteurization procedures in destroying Listeria monocytogenes and Salmonella enteritidis in liquid egg products was evaluated. Survivor studies were perfonned on individual strains of L. monocytogenes and L. innocua in commercially broken raw egg yolk samples after heating at 61.1, 63.3, and 64.4°C using submerged vials, and on Salmonella spp. at 60.0, 61.1, and 62.2°C. Surviving bacteria were enumerated on TSA and results expressed as D-values. The influence of aw -lowering ingredients such as salt and sugar on thermal resistance in yolk was investigated using a five-strain mixture of L. monocytogenes or a mixture of Salmonella spp. (four strains of S. enteritidis, one stain each of S. senftenberg and S. typhimurium) at 61.1°C to 66.7°C. At 61.1°C (present minimum temperature for pasteurization of plain egg yolk), a 7-log-unit reduction of Salmonella took 1.4 to 2.4 min, whereas a 7-log-unit reduction of L. monocytogenes took 4.9 to 16.1 min. The D-value for L. monocytogenes at 64.4°C increased from 0.44 min in plain yolk to 8.26 min after a 21.5-min lag (total time to achieve 1-log-unit reduction was 30.7 min) in yolk with 10% salt and 5% sugar, and 27.3 min after a 10.5-min lag (total time 37.8 min for 1-log-unit reduction) in yolk with 20% salt. The D-value for Salmonella in egg yolk at 64.4°C was < 0.2 min, but when 10% salt was added, the D-value was 6.4 min. Aw -lowering solutes in liquid egg yolk increased the thermal resistance of Salmonella and L. monocytogenes.

Thermal Resistance of Salmonella spp. and Listeria monocytogenes in Liquid Egg Yolk and Egg White†

1997 ◽  
Vol 60 (6) ◽  
pp. 634-638 ◽  
Author(s):  
JAMES D. SCHUMAN ◽  
BRIAN W. SHELDON
Keyword(s):  
Listeria Monocytogenes ◽  
Capillary Tube ◽  
Egg Yolk ◽  
Egg White ◽  
Heat Sensitivity ◽  
Thermal Processes ◽  
Glass Capillary ◽  
Salmonella Spp ◽  
Glass Capillary Tube ◽  
D Values

Decimal reduction times (D values) were determined for Salmonella spp. and Listeria monocytogenes (five pooled strains per pathogen) in raw liquid egg yolk (pH 6.3) and liquid egg white (pH 8.2 versus 9.1) by using a low-volume (0.05 ml per sample) immersed sealed-glass capillary-tube procedure. For Salmonella, D values ranged from 0.087 min (at 62.2°C) to 0.28 min (at 60°C) in yolk. and from 1.00 min (at 58.3°C) to 7.99 min (at 55.1° C) in egg white (pH 8.2). For Listeria, D values ranged from 0.58 min (at 62.2°C) to 1.34 min (at 60°C) in yolk, and from 2.41 min (at 58.3°C) to 7.59 min (at 55. 1°C) in egg white (pH 9.1). Mean ZD values for Salmonella ranged from 3.54 to 4.33°C; for Listeria, ZD values ranged from 6.06 to 9.43°C. In egg white, the heat sensitivity of both pathogens was enhanced at pH 9.1, although this trend was more evident for Salmonella spp. than for L. monocytogenes over the temperature range tested. The results indicate that USDA-prescribed minimal pasteurization requirements for liquid egg yolk (equivalent to 3.9- to 22.1-D processes, on the basis of the present study) would be far more lethal to the Salmonella and L. monocytogenes strains tested than would the corresponding thermal processes for liquid egg white (equivalent to 0.7- to 2.2-D processes).

Inactivation of Escherichia coli O157:H7, Salmonella enterica Serotype Enteritidis, and Listeria monocytogenes on Lettuce by Hydrogen Peroxide and Lactic Acid and by Hydrogen Peroxide with Mild Heat

2002 ◽  
Vol 65 (8) ◽  
pp. 1215-1220 ◽  
Author(s):  
CHIA-MIN LIN ◽  
SARAH S. MOON ◽  
MICHAEL P. DOYLE ◽  
KAY H. McWATTERS
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Salmonella Enteritidis ◽  
Sensory Characteristics ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Log Reduction

Iceberg lettuce is a major component in vegetable salad and has been associated with many outbreaks of foodborne illnesses. In this study, several combinations of lactic acid and hydrogen peroxide were tested to obtain effective antibacterial activity without adverse effects on sensory characteristics. A five-strain mixture of Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis, and Listeria monocytogenes was inoculated separately onto fresh-cut lettuce leaves, which were later treated with 1.5% lactic acid plus 1.5% hydrogen peroxide (H2O2) at 40°C for 15 min, 1.5% lactic acid plus 2% H2O2 at 22°C for 5 min, and 2% H2O2 at 50°C for 60 or 90 s. Control lettuce leaves were treated with deionized water under the same conditions. A 4-log reduction was obtained for lettuce treated with the combinations of lactic acid and H2O2 for E. coli O157:H7 and Salmonella Enteritidis, and a 3-log reduction was obtained for L. monocytogenes. However, the sensory characteristics of lettuce were compromised by these treatments. The treatment of lettuce leaves with 2% H2O2 at 50°C was effective not only in reducing pathogenic bacteria but also in maintaining good sensory quality for up to 15 days. A ≤4-log reduction of E. coli O157:H7 and Salmonella Enteritidis was achieved with the 2% H2O2 treatment, whereas a 3-log reduction of L. monocytogenes was obtained. There was no significant difference (P > 0.05) between pathogen population reductions obtained with 2% H2O2 with 60- and 90-s exposure times. Hydrogen peroxide residue was undetectable (the minimum level of sensitivity was 2 ppm) on lettuce surfaces after the treated lettuce was rinsed with cold water and centrifuged with a salad spinner. Hence, the treatment of lettuce with 2% H2O2 at 50°C for 60 s is effective in initially reducing substantial populations of foodborne pathogens and maintaining high product quality.

Incidence of Salmonella, Campylobacter jejuni, Campylobacter coli, and Listeria monocytogenes in Poultry Carcasses and Different Types of Poultry Products for Sale on the Belgian Retail Market

1999 ◽  
Vol 62 (7) ◽  
pp. 735-740 ◽  
Author(s):  
M. UYTTENDAELE ◽  
P. DE TROY ◽  
J. DEBEVERE
Keyword(s):  
Listeria Monocytogenes ◽  
Campylobacter Jejuni ◽  
Broiler Chickens ◽  
Salmonella Enteritidis ◽  
Contamination Level ◽  
Contamination Rate ◽  
Campylobacter Coli ◽  
Retail Market ◽  
Salmonella Spp ◽  
Poultry Products

From January 1997 to May 1998, 772 samples of poultry carcasses and poultry products for sale on the retail market in Belgium were analyzed for the presence of Salmonella spp., Salmonella Enteritidis, Campylobacter jejuni, C. coli, and Listeria monocytogenes per 100 cm2 or 25 g. Poultry samples were contaminated with Salmonella (36.5%), C. jejuni and C. coli (28.5%), and L. monocytogenes (38.2%). In about 12.3% of the poultry samples, the L. monocytogenes contamination level exceeded 1 CFU per g or cm2. Significant differences in pathogen contamination rates of poultry products were noticed between the poultry products originating from Belgian, French, and U.K. abattoirs. Poultry products derived from broiler chickens running free in pine woods until slaughtering age (12 to 13 weeks) had a significantly (P < 0.05) lower contamination rate of Salmonella than poultry products from enclosed broilers slaughtered at the age of 6 to 8 weeks. A significantly (P < 0.05) lower pathogen contamination rate was noted for Salmonella, C. jejuni, and C. coli for poultry cuts without skin compared to poultry cuts with skin on. An increase in pathogen contamination rate was noticed during cutting and further processing. To diminish C. jejuni, C. coli, Salmonella, and L. monocytogenes contamination rates, hygienic rules of slaughter and meat processing must be rigorously observed. At the moment, zero tolerance for these pathogens is not feasible, and there is a need to establish criteria allowing these pathogens to be present at reasonable levels in the examined poultry samples.

Some Chemical and Bacteriological Characteristics of Regional Cheeses from Asturias, Spain

1996 ◽  
Vol 59 (5) ◽  
pp. 509-515 ◽  
Author(s):  
ABELARDO MARGOLLES ◽  
ANA RODRIGUEZ ◽  
CLARA G. de los REYES-GAVILAN
Keyword(s):  
Listeria Monocytogenes ◽  
Listeria Innocua ◽  
Chemical Characteristics ◽  
Salmonella Spp ◽  
Cheese Making ◽  
Ph Values ◽  
Plate Counts ◽  
Coagulase Positive Staphylococci ◽  
Enrichment Methods

One hundred and one samples of six representative short-ripened cheeses (five homemade and one industrially manufactured) were collected over 1 year in several supermarkets in Asturias and analyzed for mesophilic plate counts, coliforms, enterobacteria, coagulase-positive staphylococci, the presence of species of Salmonella and Listeria, pH, moisture, NaCl, and aw. Chemical characteristics varied, largely depending on the type of cheese. The percentages of moisture and NaCl ranged from 36.11 to 48.91 and from 1.16 to 2.08 respectively. The aw values were between 0.95 and 0.99. Acidification was quite efficient, all cheeses having mean pH values between 4.56 and 5.39. None of the samples yielded Salmonella spp. Coagulase-positive staphylococci were detected in two cheeses, in one reaching levels up to 106 CFU/g. Listeria spp. contaminated 11.8% of the cheeses, with Listeria monocytogenes isolated from 8.91 % and Listeria innocua from 4.95% of the samples. The distribution of Listeria spp. varied largely depending on the type of cheese: 41% of the samples contaminated with L. monocytogeneswere obtained from one type of cheese which had the lowest pH and NaCl values and the highest aw and moisture levels of the cheeses analyzed. However, L. monocytogenes was absent from another type of cheese, which showed intermediate chemical characteristics. High levels of coliforms and enterobacteria (4 to 5 log CFU/ml) were detected in the five homemade cheeses and were statistically associated with the presence of Listeria spp. and L. monocytogenes. Cold enrichment was unsuccessful for the recovery of Listeria spp. from the cheeses analyzed, while a combination of different enrichment methods resulted in the best procedure for detecting all positive samples. This study shows that L. monocytogenes and coagulase-positive staphylococci are present in short-ripened cheeses consumed in Asturias. Adequate measures to prevent contamination during cheese making will probably result in safer products.

Antibiotic Resistance of Salmonella spp. and Listeria spp. Isolates from Traditionally Made Fresh Sausages in Greece

1998 ◽  
Vol 61 (10) ◽  
pp. 1378-1380 ◽  
Author(s):  
AMIN ABRAHIM ◽  
ANNA PAPA ◽  
NIKOLAOS SOULTOS ◽  
IOANNIS AMBROSIADIS ◽  
ANTONIS ANTONIADIS
Keyword(s):  
Antibiotic Resistance ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Salmonella Enteritidis ◽  
Antibacterial Agents ◽  
Listeria Innocua ◽  
Salmonella Spp ◽  
Listeria Welshimeri ◽  
Butcher Shops

Sixty-five samples of traditionally made fresh sausages obtained from retail shops and butcher shops in northem Greece were screened for the presence of Salmonella spp. and Listeria spp. Salmonella spp. were found in 20% of the samples tested (54% Salmonella typhimurium and 46% Salmonella enteritidis). The prevalence of Listeria spp. in the samples was 26% (12% Listeria monocytogenes, 76% Listeria innocua, and 12% Listeria welshimeri). Nine of 13 Salmonella isolates were found to be resistant to ampicillin and 4 of 13 showed intermediate sensitivity; 1 of 13 was found to be resistant to chloramphenicol and 1 of 13 to tetracycline. Two strains of Salmonella typhimurum were multiresistant (resistant to ampicillin, chloramphenicol, and norfloxacin). All Listeria isolates were sensitive to the antibacterial agents tested that are commonly used for the treatment of human listeriosis.

Inactivation of Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes on Apples, Oranges, and Tomatoes by Lactic Acid with Hydrogen Peroxide

2002 ◽  
Vol 65 (1) ◽  
pp. 100-105 ◽  
Author(s):  
KUMAR S. VENKITANARAYANAN ◽  
CHIA-MIN LIN ◽  
HANNALORE BAILEY ◽  
MICHAEL P. DOYLE
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Chemical Treatment ◽  
Salmonella Enteritidis ◽  
Deionized Water ◽  
Wash Water ◽  
Escherichia Coli O157 ◽  
E Coli

The objective of this study was to develop a practical and effective method for inactivating or substantially reducing Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes on apples, oranges, and tomatoes. Apples, oranges, and tomatoes were spot-inoculated with five-strain mixtures of E. coli O157:H7, Salmonella Enteritidis, and L. monocytogenes near the stem end and were submerged in sterile deionized water containing 1.5% lactic acid plus 1.5% hydrogen peroxide for 15 min at 40°C. Inoculated samples treated with sterile deionized water at the same temperature and for the same duration served as controls. The bacterial pathogens on fruits subjected to the chemical treatment were reduced by >5.0 log10 CFU per fruit, whereas washing in deionized water decreased the pathogens by only 1.5 to 2.0 log10 CFU per fruit. Furthermore, substantial populations of the pathogens survived in the control wash water, whereas no E. coli O157:H7, Salmonella Enteritidis, or L. monocytogenes cells were detected in the chemical treatment solution. The sensory and qualitative characteristics of apples treated with the chemical wash solution were not adversely affected by the treatment. It was found that the treatment developed in this study could effectively be used to kill E. coli O157:H7, Salmonella Enteritidis, and L. monocytogenes on apples, oranges, and tomatoes at the processing or packaging level.

Reduction of Salmonella by Two Commercial Egg White Pasteurization Methods

2004 ◽  
Vol 67 (6) ◽  
pp. 1177-1183 ◽  
Author(s):  
W. R. ROBERTSON ◽  
P. M. MURIANA
Keyword(s):  
Hydrogen Peroxide ◽  
Capillary Tube ◽  
Egg White ◽  
Low Ph ◽  
Residence Times ◽  
Processing Conditions ◽  
Effect Of Ph ◽  
Log Reduction ◽  
D Values ◽  
Almost All

The effect of pH, processing temperatures, and preheating steps in two commercial egg white pasteurization procedures (Armour and Standard Brands methods) were evaluated using a five-strain cocktail of Salmonella. We devised a benchtop pasteurization system that would more closely resemble the two commercial processes than could the traditional capillary tube method. The pasteurization methods both require hydrogen peroxide to be metered into the egg white stream between a required initial preheat step and the main heating regimen. Both processes were evaluated at three pH levels (pH 8.2, 8.6, 9.0), at four temperatures (51.7°C/125°F, 53.1°C/127.5°F, 54.4°C/130°F, 55.8°C/132.5°F), and over four residence times to allow calculation of D-values at each temperature. When compared at the minimum allowable time and temperatures for each process, our results showed at least a 1-log greater log reduction (P < 0.05) for the Standard Brands method than the Armour method in 10 of 12 of the pH and temperature combinations tested. Almost all runs at any given temperature showed more reduction at pH 9.0 than at pH 8.2 except for the Standard Brands method at 54.4°C and 55.8°C, which showed the most consistent reduction across all three pH levels tested. Analysis of the preheat portion of the two methods showed that there was no contribution (P > 0.05) toward Salmonella reduction when compared with the identical process without the preheating step. We generally observed a greater reduction of Salmonella with egg white at pH 9.0 that is typical of older, off-line processing than with low pH egg white (i.e., 8.2) that is typical of modern in-line processing facilities. This difference was as much as 3.5 log cycles depending on the processing conditions. The data has been used to make recommendations for minimum processing conditions for hydrogen peroxide–based egg white pasteurization.

Predictive Thermal Inactivation Model for Listeria monocytogenes with Temperature, pH, NaCl, and Sodium Pyrophosphate as Controlling Factors†

1999 ◽  
Vol 62 (9) ◽  
pp. 986-993 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
BRIAN S. EBLEN
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Predictive Model ◽  
Heating Temperature ◽  
Sodium Pyrophosphate ◽  
Effect Of Temperature ◽  
Plate Count ◽  
Heat Inactivation ◽  
Heat Sensitivity ◽  
D Values

The effects and interactions of heating temperature (55 to 65°C), pH (4 to 8), salt (NaCl; 0 to 6%, wt/vol), and sodium pyrophosphate (SPP; 0 to 0.3%, wt/vol) on the heat inactivation of a four-strain mixture of Listeria monocytogenes in beef gravy were examined. A factorial experimental design comparing 48 combinations of heating temperature, salt concentration, pH value, and SPP content was used. Heating was carried out using a submerged-coil heating apparatus. The recovery medium was plate count agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. Decimal reduction times (D-values) were calculated by fitting a survival model to the data with a curve-fitting program. The D-values were analyzed by second-order response surface regression for temperature, pH, NaCl, and SPP levels. Whereas increasing the NaCl concentration protected L. monocytogenes against the lethal effect of heat, high SPP concentrations increased heat sensitivity. Also, low pH values increased heat sensitivity of L. monocytogenes. The four variables interacted to affect the inactivation of the pathogen. Thermal resistance of L. monocytogenes can be lowered by combining these intrinsic factors. A predictive model that described the combined effect of temperature, pH, NaCl, and SPP levels on thermal resistance of L. monocytogenes was developed. The model can predict D-values for any combination of temperature, pH, NaCl, and SPP that are within the range of those tested. Using this predictive model, food processors should be able to design adequate thermal regimes to eliminate L. monocytogenes in thermally processed foods.

scholarly journals A Simple Gold Nanoprobe Assay for the Identification of Staphylococcus Aureus, Listeria Monocytogenes and Salmonella Enteritidis in Food Specimens

2017 ◽  
Vol 6 (4) ◽  
pp. 134 ◽  
Author(s):  
Dimitra Panagiotis Houhoula ◽  
Ekatherina Charvalos ◽  
Spyros Konteles ◽  
Stamatis Koussissis ◽  
Vladimiros Lougovois ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Dna Sequences ◽  
Salmonella Enteritidis ◽  
Screening Method ◽  
Pcr Amplification ◽  
Reference Method ◽  
Direct Pcr ◽  
Salmonella Spp ◽  
Gold Nanoprobe

In the present study, we developed a gold nanoprobe assay, which relies on the colorimetric differentiation of specific DNA sequences, based on different aggregation profiles. We evaluated the assay on DNA extracted from pathogen cultures and from contaminated food specimens. The targets used were the femA gene for the identification of Staphylococcus aureus, the hly gene of the Listeria monocytogenes listeriolysin and the invA sequence for Salmonella spp. Comparison was performed with the reference assay, as described in the respective ISO guidelines for each pathogen, and a direct PCR amplification and detection. The minimum detection limit of the assay was defined at 123 fg/μL DNA, for all species, lower than PCR detection. Specificity was 100%. Sensitivity was 100%, as compared το the reference method, whereas the sensitivity of PCR was 93.3%. The evaluated assay could be used as a sensitive screening method, which does not require major infrastructure, for the detection and identification of pathogens in food specimens. In addition, it can accommodate detection of multiplespecies,thus allowing multiplexingand expedite turnaround time. 

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