scholarly journals Heat Resistance of Listeria monocytogenes in Dairy Matrices Involved in Mozzarella di Bufala Campana PDO Cheese

2021 ◽  
Vol 11 ◽  
Author(s):  
Annalisa Ricci ◽  
Marcello Alinovi ◽  
Francesco Martelli ◽  
Valentina Bernini ◽  
Alessandro Garofalo ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Industrial Process ◽  
Lethal Effect ◽  
Protected Designation Of Origin ◽  
The Matrix ◽  
Pasta Filata ◽  
Cheese Curd ◽  
Fresh Pasta

The presence of Listeria monocytogenes in Mozzarella di Bufala Campana Protected Designation of Origin cheeses may depend on curd stretching conditions and post contaminations before packaging. To avoid cross-contamination, thermal treatment of water, brines and covering liquid may become necessary. The present study aimed to improve knowledge about L. monocytogenes thermal resistance focusing on the influence of some cheese making operations, namely curd stretching and heat treatment of fluids in contact with cheese after molding, in order to improve the safety of the cheese, optimize efficacy and sustainability of the processes. Moreover, the role that cheese curd stretching plays in L. monocytogenes inactivation was discussed. The 12 tested strains showed a very heterogeneous heat resistance that ranged from 7 to less than 1 Log10 Cfu/mL reduction after 8 min at 60°C. D-values (decimal reduction times) and z-values (thermal resistance constant) calculated for the most heat resistant strain among 60 and 70°C were highly affected by the matrix and, in particular, heat resistance noticeably increased in drained cheese curd. As cheese curd stretching is not an isothermal process, to simulate the overall lethal effect of an industrial process a secondary model was built. The lethal effect of the process was estimated around 4 Log10 reductions. The data provided may be useful for fresh pasta filata cheese producers in determining appropriate processing durations and temperatures for producing safe cheeses.

Modeling the Effects of Temperature, Sodium Chloride, and Green Tea and Their Interactions on the Thermal Inactivation of Listeria monocytogenes in Turkey†

2014 ◽  
Vol 77 (10) ◽  
pp. 1696-1702 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
JIMENA GARCIA-DÁVILA ◽  
JULIO CESAR LOPEZ-ROMERO ◽  
ETNA AIDA PENA-RAMOS ◽  
JUAN PEDRO CAMOU ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Sodium Chloride ◽  
Protective Effect ◽  
Heat Resistance ◽  
Green Tea ◽  
Thermal Inactivation ◽  
Heating Temperature ◽  
Lethal Effect ◽  
Interactive Effects ◽  
D Values

The interactive effects of heating temperature (55 to 65°C), sodium chloride (NaCl; 0 to 2%), and green tea 60% polyphenol extract (GTPE; 0 to 3%) on the heat resistance of a five-strain mixture of Listeria monocytogenes in ground turkey were determined. Thermal death times were quantified in bags that were submerged in a circulating water bath set at 55, 57, 60, 63, and 65°C. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. D-values were analyzed by second-order response surface regression for temperature, NaCl, and GTPE. The data indicated that all three factors interacted to affect the inactivation of the pathogen. The D-values for turkey with no NaCl or GTPE at 55, 57, 60, 63, and 65°C were 36.3, 20.8, 13.2, 4.1, and 2.9 min, respectively. Although NaCl exhibited a concentration-dependent protective effect against heat lethality on L. monocytogenes in turkey, addition of GTPE rendered the pathogen more sensitive to the lethal effect of heat. GTPE levels up to 1.5% interacted with NaCl and reduced the protective effect of NaCl on heat resistance of the pathogen. Food processors can use the predictive model to design an appropriate heat treatment that would inactivate L. monocytogenes in cooked turkey products without adversely affecting the quality of the product.

Thermal Destruction of Listeria monocytogenes in Ice Cream Mix

1992 ◽  
Vol 55 (4) ◽  
pp. 234-237 ◽  
Author(s):  
V. H. HOLSINGER ◽  
P. W. SMITH ◽  
J. L. SMITH ◽  
S. A. PALUMBO
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Thermal Destruction ◽  
Variable Viscosity ◽  
Ice Cream ◽  
High Fructose Corn Syrup ◽  
Corn Syrup ◽  
High Fructose ◽  
Solids Content

Thermal destruction of Listeria monocytogenes strain Scott A was studied in refrigerated ice cream mixes to evaluate the relationship of mix composition to heat resistance with differing heat treatments. A central composite response surface design with two independent variables (high fructose corn syrup solids content and milkfat content) and one dependent variable (viscosity of the mix) was developed. High fructose corn syrup solids (HFCSS) content ranged from 1 to 7%, milkfat (MF) content from 4 to 18%, and total solids content from 28 to 44%. Sucrose content (11%) and milk-solids-not-fat content (10%) were kept constant. D140°F values were established in the mixes with a simulated batch pasteurization procedure using closed vials. Survivor data indicated sigmoidal responses with initial shoulders and tailing, but shoulder values were not significantly affected by either HFCSS or MF. D and F (F = 7D + shoulder) values were significantly (p = 0.01, R2 = .88; p = 0.01, R2 = .89, respectively) correlated to HCFSS content with increasing heat resistance conferred at higher concentrations. MF content had little or no effect on thermal death time but had a greater effect on viscosity of the mix than did content of HFCSS. Increased thermal resistance of LM was associated with the common ice cream stabilizer used; stabilizer contained guar gum and carrageenan. Pasteurization guidelines for ice cream mix are adequate to ensure inactivation of LM. Since results suggest that major ingredients in ice cream, ice milk, and shake mixes increase thermal resistance of LM, it is important that every precaution be taken to inactivate the organism.

Comparison of Heat Resistance of Listeria monocytogenes in Milk as Determined by Two Methods

1987 ◽  
Vol 50 (1) ◽  
pp. 14-17 ◽  
Author(s):  
CATHERINE W. DONNELLY ◽  
ELIZABETH H. BRIGGS ◽  
L. SCOTT DONNELLY
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Thermal Inactivation ◽  
Test Tube ◽  
Initial Population ◽  
Tube Versus

The thermal resistance of 3 strains of Listeria monocytogenes was compared using test tube versus sealed tube methods of thermal inactivation. All L. monocytogenes strains were rapidly inactivated in milk when survival was measured using sealed tube thermal inactivation methods. Calculated D62°C values ranged between 0.1–0.4 min for the three strains tested. In contrast, total inactivation of L. monocytogenes populations using test tube methods of thermal inactivation could not be accomplished within 30 min at 62°C. Extensive tailing of survivor curves was consistently observed. When an initial population of 5 × 106 L. monocytogenes/ml was heated at 72, 82, or 92°C, consistent survival of a population of 102–103 L. monocytogenes/ml after 30 min was observed. The results prove that the test tube method for measuring thermal resistance of L. monocytogenes is inaccurate. Reports of extraordinary heat resistance based upon this method are correspondingly inaccurate. L. monocytogenes cells, dispersed freely in milk, will not survive pasteurization.

Heat Resistance and Growth of Listeria monocytogenes in Liquid Whole Egg1,2

1990 ◽  
Vol 53 (1) ◽  
pp. 9-14 ◽  
Author(s):  
PEGGY M. FOEGEDING ◽  
SUSAN B. LEASOR
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Growth Temperature ◽  
Generation Times ◽  
Liquid Whole Egg ◽  
D Values ◽  
Whole Egg

Listeria monocytogenes F5069, ATCC 19111, Scott A, and two L. monocytogenes strains isolated from egg were evaluated for growth and thermal resistance in liquid whole egg. Each strain grew in liquid whole egg at temperatures between 4 and 30°C, except Scott A which did not grow at 4 or 10°C. Generation times ranged from 24 h for F5069 to 51 h for ATCC 19111 at 4°C and from 7.8 h for one of the egg isolates to 31 h for ATCC 19111 at 10°C. Maximum populations for each strain increased with increasing growth temperature and were between 105 and 3 × 108 CFU/g. Decimal reduction times (D-values) of each L. monocytogenes strain in raw liquid whole egg were similar to D-values reported in milk. The heat resistance of all strains was similar. For L. monocytogenes F5069, D-values ranged from 22.6 min at 51°C to 0.20 min at 66°C. The zD-value for F5069 was 7.2°C. Minimal pasteurization parameters (60°C, 3.5 min) for liquid whole egg would result in 99 to 99.9% inactivation (populations reduced 2 to 3 log cycles) of the L. monocytogenes strains tested.

Listeria in Seafoods: A Review

1992 ◽  
Vol 55 (12) ◽  
pp. 1009-1015 ◽  
Author(s):  
RONDA M. DILLON ◽  
THAKOR R. PATEL
Keyword(s):  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Drug Administration ◽  
Food And Drug Administration ◽  
Environmental Contaminant ◽  
Fresh Waters ◽  
Smoked Fish ◽  
Seafood Products ◽  
Crab Meat

Listeria is an environmental contaminant which has been isolated from marine and fresh waters, as well as various seafoods. Furthermore, Listeria, including Listeria monocytogenes, has been isolated from processed seafood products such as smoked fish, cooked and frozen seafoods, marinated fish, surimi products, etc. The pathogen, L. monocytogenes, does have a certain degree of heat resistance. It was found to survive in internally infected shrimp after boiled for up to 5 min. However, the commercial pasteurization process for crab meat was found to be sufficient to inactivate Listeria. The current recovery methodology for L. monocytogenes from seafoods is the Food and Drug Administration Listeria protocol.

Effective Thermal Conductivity of Functionally Graded Particulate Nanocomposites With Interfacial Thermal Resistance

2008 ◽  
Vol 75 (5) ◽  
Author(s):  
H. M. Yin ◽  
G. H. Paulino ◽  
W. G. Buttlar ◽  
L. Z. Sun
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Functionally Graded ◽  
Interfacial Thermal Resistance ◽  
Conductivity Distribution ◽  
Consistent Model ◽  
The Matrix ◽  
Graded Material ◽  
Perfect Interface

By means of a fundamental solution for a single inhomogeneity embedded in a functionally graded material matrix, a self-consistent model is proposed to investigate the effective thermal conductivity distribution in a functionally graded particulate nanocomposite. The “Kapitza thermal resistance” along the interface between a particle and the matrix is simulated with a perfect interface but a lower thermal conductivity of the particle. The results indicate that the effective thermal conductivity distribution greatly depends on Kapitza thermal resistance, particle size, and degree of material gradient.

Thermal resistance of Listeria monocytogenes in inoculated and naturally contaminated raw milk

1988 ◽  
Vol 7 (4) ◽  
pp. 277-286 ◽  
Author(s):  
J.M. Farber ◽  
G.W. Sanders ◽  
J.I. Speirs ◽  
J.-Y. D'Aoust ◽  
D.B. Emmons ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Raw Milk

Effect of Aerogel Incorporation in PCM-Containing Thermal Liner of Firefighting Garment

2018 ◽  
Vol 36 (3) ◽  
pp. 151-164 ◽  
Author(s):  
Abu Shaid ◽  
Lijing Wang ◽  
Stanley M. Fergusson ◽  
Rajiv Padhye
Keyword(s):  
Thermal Properties ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Phase Change ◽  
Phase Change Material ◽  
Protective Clothing ◽  
Ignition Time ◽  
Current Case ◽  
The Mean ◽  
Change Material

Phase change material (PCM) in firefighting garment enhances protection and comfort. Wearing a protective clothing containing PCM, while fighting the fire, is a direct risk to the wearer as most PCMs used are flammable. This article reports a solution by using aerogel. Thermal liner fabric was treated with PCM and/or aerogel and then their thermal properties were analyzed. It has been found that the mean ignition time of PCM-containing thermal liner is around 3.3 s in current case while this value significantly increased to 5.5 s when the combination of aerogel and PCM was used. Moreover, the weight of the liner fabric with aerogel decreased in comparison to PCM-containing liner. Aerogel also slowed down the spreading of flame in PCM-containing fabric. Aerogel–coated liner showed superior heat resistance and the combination of aerogel with PCM increased the thermal resistance of PCM-containing liner.

Inactivation of the Crp/Fnr Family of Regulatory Genes in Listeria monocytogenes Strain F2365 Does Not Alter Its Heat Resistance at 60°C†

2006 ◽  
Vol 69 (11) ◽  
pp. 2758-2760 ◽  
Author(s):  
DARRELL O. BAYLES ◽  
GAYLEN A. UHLICH
Keyword(s):  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Thermal Tolerance ◽  
Type Strain ◽  
Transcriptional Control ◽  
Wild Type Strain ◽  
Gene Cassette ◽  
Wild Type ◽  
Mutant Strains ◽  
Virulence Regulator

A surprising facet of the Listeria monocytogenes genome is the presence of 15 genes that code for regulators in the Crp/Fnr family and include the virulence regulator PrfA. The genes under the transcriptional control of these regulators are currently undetermined, with the exception of some genes controlled by the major virulence regulator PrfA. Using 12 strains of L. monocytogenes, each with an inserted gene cassette that interrupts and renders nonfunctional a different L. monocytogenes strain F2365 Crp/Fnr regulator, we heat challenged each strain at 60°C with an immersed-coil heating apparatus, modeled the survivor data to calculate the underlying mean and mode of the heat resistance distribution for each strain, and compared the thermal tolerance of each mutant to the wild-type strain to determine if any of the Crp/Fnr mutants demonstrated altered heat tolerance. All 12 of the Crp/Fnr mutant strains tested had heat resistance characteristics similar to the wild-type strain (P > 0.05), indicating that mutations in these Crp/Fnr genes neither increased nor decreased the sensitivity of L. monocytogenes strain F2365 to mild heat.

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