scholarly journals Persistent and Nonpersistent Listeria monocytogenes Contamination in Meat and Poultry Processing Plants

2003 ◽  
Vol 66 (11) ◽  
pp. 2062-2069 ◽  
Author(s):  
JANNE M. LUNDÉN ◽  
TIINA J. AUTIO ◽  
A.-M. SJÖBERG ◽  
HANNU J. KORKEALA
Keyword(s):  
Heat Treatment ◽  
Listeria Monocytogenes ◽  
Sampling Site ◽  
Pfge Type ◽  
Processing Plant ◽  
Post Heat Treatment ◽  
Common Location ◽  
Heat Treated ◽  
Processing Plants ◽  
Poultry Processing

Contamination analysis of persistent and nonpersistent Listeria monocytogenes strains in three meat processing plants and one poultry processing plant were performed in order to identify factors predisposing to or sustaining persistent plant contamination. A total of 596 L. monocytogenes isolates were divided into 47 pulsed-field gel electrophoresis (PFGE) types by combining the restriction enzyme patterns of AscI (42 patterns) and ApaI (38 patterns). Persistent and nonpersistent strains were found in all plants. Nonpersistent PFGE types were found mostly at one sampling site, with the processing environment being the most common location, whereas the persistent strains were found at several sampling sites in most cases. The processing machines were frequently contaminated with persistent L. monocytogenes PFGE types, and it was of concern that surfaces having direct contact with the products were contaminated. The role of the processing machines in sustaining contamination and in contaminating the products appeared to be important because the final product of several processing lines was contaminated with the same L. monocytogenes PFGE type as that found in the processing machine. The proportion of persistent PFGE types in heat-treated products was eight times higher than in the raw products, showing the importance of the persistent PFGE types as contaminants of the final heat-treated products. The contamination status of the processing lines and machines appeared to be influenced by the compartmentalization of the processing line, with poor compartmentalization increasing L. monocytogenes contamination. The separation of raw and post–heat treatment areas seemed especially important in the contamination status of post–heat treatment lines.

scholarly journals The Connection between Persistent, Disinfectant-Resistant Listeria monocytogenes Strains from Two Geographically Separate Iberian Pork Processing Plants: Evidence from Comparative Genome Analysis

2015 ◽  
Vol 82 (1) ◽  
pp. 308-317 ◽  
Author(s):  
Sagrario Ortiz ◽  
Victoria López-Alonso ◽  
Pablo Rodríguez ◽  
Joaquín V. Martínez-Suárez
Keyword(s):  
Listeria Monocytogenes ◽  
Food Processing ◽  
Pfge Type ◽  
Processing Plant ◽  
Content Type ◽  
Pork Products ◽  
Processing Plants ◽  
Pork Product ◽  
Ammonium Compounds ◽  
Insight Into

ABSTRACTThe aim of this study was to investigate the basis of the putative persistence ofListeria monocytogenesin a new industrial facility dedicated to the processing of ready-to-eat (RTE) Iberian pork products. Quaternary ammonium compounds, which included benzalkonium chloride (BAC), were repeatedly used as surface disinfectants in the processing plant. Clean and disinfected surfaces were sampled to evaluate if resistance to disinfectants was associated with persistence. Of the 14 isolates obtained from product contact and non-product contact surfaces, only five different pulsed-field gel electrophoresis (PFGE) types were identified during the 27-month study period. Two of these PFGE types (S1 and S10-1) were previously identified to be persistent and BAC-resistant (BACr) strains in a geographically separate slaughterhouse belonging to the same company. The remaining three PFGE types, which were first identified in this study, were also BACr. Whole-genome sequencing andin silicomultilocus sequence typing (MLST) analysis of five BACrisolates of the different PFGE types identified in this study showed that the isolate of the S1 PFGE type belonged to MLST sequence type 31 (ST31), a low-virulence type characterized by mutations in theinlAandprfAgenes. The isolates of the remaining four PFGE types were found to belong to MLST ST121, a persistent type that has been isolated in several countries. The ST121 strains contained the BAC resistance transposon Tn6188. The disinfection-resistantL. monocytogenespopulation in this RTE pork product plant comprised two distinct genotypes with different multidrug resistance phenotypes. This work offers insight into theL. monocytogenessubtypes associated with persistence in food processing environments.

A Predictive Model for Heat Inactivation of Listeria monocytogenes Biofilm on Stainless Steel

2004 ◽  
Vol 67 (12) ◽  
pp. 2712-2718 ◽  
Author(s):  
R. A. N. CHMIELEWSKI ◽  
JOSEPH F. FRANK
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Predictive Model ◽  
Enrichment Culture ◽  
Hot Water ◽  
Management Tool ◽  
Heat Inactivation ◽  
Heat Treated ◽  
Processing Plants

Heat treatment of potential biofilm-forming sites is sometimes used for control of Listeria monocytogenes in food processing plants. However, little information is available on the heat treatment required to kill L. monocytogenes present in biofilms. The purpose of this study was to develop a predictive model for the heat inactivation of L. monocytogenes in monoculture biofilms (strains Scott A and 3990) and in biofilms with competing bacteria (Pseudomonas sp. and Pantoea agglomerans) formed on stainless steel in the presence of food-derived soil. Biofilms were produced on stainless steel coupons with diluted tryptic soy broth incubated for 48 h at 25°C. Duplicate biofilm samples were heat treated for 1, 3, 5, and 15 min at 70, 72, 75, 77, and 80°C and tested for survivors using enrichment culture. The experiment was repeated six times. A predictive model was developed using logistic regression analysis of the fraction negative data. Plots showing the probability of L. monocytogenes inactivation in biofilms after heat treatment were generated from the predictive equation. The predictive model revealed that hot water sanitation of stainless steel can be effective for inactivating L. monocytogenes in a biofilm on stainless steel if time and temperature are controlled. For example, to obtain a 75% probability of total inactivation of L. monocytogenes 3990 biofilm, a heat treatment of 80°C for 11.7 min is required. The model provides processors with a risk management tool that provides predicted probabilities of L. monocytogenes inactivation and allows a choice of three heat resistance assumptions. The predictive model was validated using a five-strain cocktail of L. monocytogenes in the presence of food soil.

Traceback Identification of an Ingredient (Pork Dewlap) as the Possible Source of Listeria monocytogenes Serotype 4b Contamination in Raw Chicken Products

2007 ◽  
Vol 70 (6) ◽  
pp. 1513-1517 ◽  
Author(s):  
VICTORIA LÓPEZ ◽  
SAGRARIO ORTIZ ◽  
ALFREDO CORUJO ◽  
PILAR LÓPEZ ◽  
JAIME NAVAS ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Restriction Analysis ◽  
Virulence Gene ◽  
Pulsed Field Gel Electrophoresis ◽  
Processing Plant ◽  
Poultry Processing ◽  
Serotype 4B ◽  
Fresh Products ◽  
Allelic Analysis

In surveys conducted on finished product samples from a single poultry processing plant in Spain, Listeria monocytogenes was found in 14 different uncooked products. To track contamination patterns, 77 L. monocytogenes isolates were characterized by PCR-based serotyping, pulsed-field gel electrophoresis (PFGE) restriction analysis, and PCR-based allelic analysis of the virulence gene actA. Serotyping revealed that 12 isolates (15.6%) were of the L. monocytogenes serotype 4b complex (serotype 4b or the closely related serotypes 4d and 4e). A combination of endonucleases AscI and ApaI PFGE patterns yielded 15 different pulsotypes among all 77 tested isolates. All the serotype 4b isolates belonged to one pulsotype. Sequencing of the actA gene confirmed that all serotype 4b isolates corresponded to the same allelic subtype. The subtype was recovered from five product types, but its presence was not correlated with the production line or the date of isolation, suggesting a possible association of this strain with a common ingredient. This traceback investigation established that pork dewlap, an ingredient common to all the products contaminated with this strain, was the most probable source of L. monocytogenes 4b. The same 4b strain was isolated from four samples of pork dewlap from one specific supplier. After replacement of this contaminated ingredient in the fresh products, this strain of L. monocytogenes serotype 4b was not detected. This study confirms the effectiveness of molecular subtyping to control contamination by specific strains of L. monocytogenes and the importance of testing the different ingredients added to the food products.

scholarly journals Effects of Post Heat Treatment on the Mechanical Properties of Cold-Rolled Ti/Cu Clad Sheet

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1672
Author(s):  
Chang-Suk Youn ◽  
Dong-Geun Lee
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Rolling Process ◽  
Post Treatment ◽  
Post Heat Treatment ◽  
Clad Sheet ◽  
Heat Treated ◽  
Bonding Properties ◽  
High Elongation ◽  
Cold Rolled

Titanium and titanium alloys have excellent corrosion and heat resistance, but weak electric and thermal conductivity. The weak conductivity of titanium can be overcome by cladding with copper, which has high conductivity. Although titanium is expensive, it is selected as a material suitable for applications requiring corrosion resistance such as in heat exchangers. This study was to investigate the effect of post heat treatment on the mechanical properties of the Ti/Cu cold-rolled clad plate by using the interfacial diffusion bonding. A titanium clad by cold rolling should be heat-treated after the rolling process to improve the bonding properties through the diffusion of metals and removal of residual stress due to work hardening, despite the easy formation of intermetallic compounds of Ti and Cu. As a result post-treatment, the elongation was improved by more than two times from 21% to max. 53% by the Ti-Cu interface diffusion phenomenon and the average tensile strength of the 450 °C heat-treated specimens was 353 MPa. By securing high elongation while maintaining excellent tensile and yield strength through post-treatment, the formability of Ti-Cu clad plate can be greatly improved.

Prevalence of Listeria monocytogenes in Broilers at the Abattoir, Processing Plant, and Retail Level

2001 ◽  
Vol 64 (7) ◽  
pp. 994-999 ◽  
Author(s):  
MARIA K. MIETTINEN ◽  
LIISA PALMU ◽  
K. JOHANNA BJÖRKROTH ◽  
HANNU KORKEALA
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Conveyor Belt ◽  
Pulsed Field Gel Electrophoresis ◽  
Contamination Level ◽  
Contamination Rate ◽  
Processing Plant ◽  
Broiler Meat ◽  
Pulsed Field ◽  
Processing Plants

The environment and products from two broiler abattoirs and processing plants and raw broiler pieces at the retail level were sampled for Listeria monocytogenes in order to evaluate the contamination level of the broiler carcasses and products. Sampling started in the slaughtering process and finished with raw broiler meat or ready-to-eat cooked product. Sampling sites positive for L. monocytogenes at the broiler abattoir were the air chiller, the skin-removing machine, and the conveyor belt leading to the packaging area. The L. monocytogenes contamination rate varied from 1 to 19% between the two plants studied. Furthermore, 62% (38 of 61) of the raw broiler pieces, bought from retail stores, were positive for L. monocytogenes. Altogether, 136 L. monocytogenes isolates were obtained for serotyping and pulsed-field gel electrophoresis(PFGE) characterization performed with two rare-cutting enzymes (ApaI and AscI). Altogether three serotypes (1/2a, 1/2c, and 4b) and 14 different PFGE types were obtained using information provided from both ApaI and AscI patterns for discrimination basis. The two broiler abattoirs studied did not share the same PFGE types. However, the same PFGE types found in the raw broiler pieces at the retail level were also found in the broiler abattoirs where the broilers had been slaughtered.

Cleaning Conveyor Belts in the Chicken-Cutting Area of a Poultry Processing Plant with 45°C Water

2014 ◽  
Vol 77 (3) ◽  
pp. 496-498 ◽  
Author(s):  
V. M. SOARES ◽  
J. G. PEREIRA ◽  
C. M. ZANETTE ◽  
L. A. NERO ◽  
J. P. A. N. PINTO ◽  
...  
Keyword(s):  
Conveyor Belt ◽  
Hot Water ◽  
Poultry Meat ◽  
Processing Plant ◽  
Meat Processing ◽  
Work Shift ◽  
Processing Facility ◽  
Processing Plants ◽  
Conveyor Belts ◽  
Poultry Processing

Conveyor belts are widely used in food handling areas, especially in poultry processing plants. Because they are in direct contact with food and it is a requirement of the Brazilian health authority, conveyor belts are required to be continuously cleaned with hot water under pressure. The use of water in this procedure has been questioned based on the hypothesis that water may further disseminate microorganisms but not effectively reduce the organic material on the surface. Moreover, reducing the use of water in processing may contribute to a reduction in costs and emission of effluents. However, no consistent evidence in support of removing water during conveyor belt cleaning has been reported. Therefore, the objective of the present study was to compare the bacterial counts on conveyor belts that were or were not continuously cleaned with hot water under pressure. Superficial samples from conveyor belts (cleaned or not cleaned) were collected at three different times during operation (T1, after the preoperational cleaning [5 a.m.]; T2, after the first work shift [4 p.m.]; and T3, after the second work shift [1:30 a.m.]) in a poultry meat processing facility, and the samples were subjected to mesophilic and enterobacterial counts. For Enterobacteriaceae, no significant differences were observed between the conveyor belts, independent of the time of sampling or the cleaning process. No significant differences were observed between the counts of mesophilic bacteria at the distinct times of sampling on the conveyor belt that had not been subjected to continuous cleaning with water at 45°C. When comparing similar periods of sampling, no significant differences were observed between the mesophilic counts obtained from the conveyor belts that were or were not subjected to continuous cleaning with water at 45°C. Continuous cleaning with water did not significantly reduce microorganism counts, suggesting the possibility of discarding this procedure in chicken processing.

scholarly journals Detection and quantification of Campylobacter spp. in Brazilian poultry processing plants

2020 ◽  
Vol 14 (01) ◽  
pp. 109-113
Author(s):  
Karen A Borges ◽  
Isabel C Cisco ◽  
Thales Q Furian ◽  
Denise C Tedesco ◽  
Laura B Rodrigues ◽  
...  
Keyword(s):  
High Specificity ◽  
Culture Method ◽  
Human Infection ◽  
Food Preservation ◽  
Processing Plant ◽  
Cross Contamination ◽  
Bacterial Survival ◽  
Processing Plants ◽  
Poultry Processing ◽  
Campylobacter Spp

Introduction: Campylobacteriosis is considered the most common bacteria-caused human gastroenteritis in the world. Poultry is a major reservoir of Campylobacter. Human infection may occur by consumption of raw and undercooked poultry or by contamination of other foods by these items. The aim of this study was to assess the prevalence of Campylobacter spp. in poultry processing plants with conventional culture method and real-time PCR. Methodology: A total of 108 poultry processing plant samples were collected to test with conventional microbiology and qPCR. Sampling included cloacal swabs, swabs of transport crates (before and after the cleaning and disinfection process) and carcasses (after the chiller, cooled at 4°C and frozen at −12°C). Results: Positivity in cloacal swabs indicated that poultry arrived contaminated at the slaughterhouse. Contamination in transport cages was substantially increased after the cleaning process, indicating that the process was ineffective. The detection of Campylobacter on carcasses was higher than that on cloacal swabs, which could indicate cross-contamination during the slaughtering process. Conventional microbiology and molecular methods revealed a prevalence of 69.4% and 43.5%, respectively. Lower detection by qPCR can be attributed to the high specificity of the kit and to biological components that could inhibit PCR reactions. Conclusions: Our results indicate that poultry arrive contaminated at the slaughterhouse and that contamination can increase during the slaughtering process due to cross-contamination. The isolation of Campylobacter in cooled and frozen carcasses corroborates the bacterial survival even at temperatures considered limiting to bacterial growth which are routinely used for food preservation.

Prevalence and Typing of Listeria monocytogenes in Raw Catfish Fillets†

2006 ◽  
Vol 69 (4) ◽  
pp. 815-819 ◽  
Author(s):  
CHUNG-HSI CHOU ◽  
JUAN L. SILVA ◽  
CHINLING WANG
Keyword(s):  
Listeria Monocytogenes ◽  
Repetitive Element ◽  
Group Method ◽  
Processing Plant ◽  
Natural Habitats ◽  
Listeria Species ◽  
Pair Group ◽  
Catfish Fillets ◽  
Processing Plants ◽  
Different Seasons

Raw channel catfish fillets collected from three processing plants during four time periods were tested for the presence of Listeria species. Listeria monocytogenes was the predominant Listeria species found in these catfish fillets, with 25 to 47% prevalence. Other Listeria species, such as L. welshimeri, L. innocua, L. ivanovii, L. grayi, and L. seeligeri, were also found. L. monocytogenes isolates were further fingerprinted by a repetitive element PCR. Forty distinctive electrophoretic types (ETs) and three genetic clusters were determined by Dice coefficient analysis and UPGMA (unweighted pair group method using arithmetic averages). Twenty of 40 ETs were represented by a single isolate, and the other 20 ETs were represented by 2 to 11 isolates. Thirty-five ETs, represented by 76 isolates, were found in processing plant A, B, or C and designated plant-specific types. The remaining five ETs, represented by 21 isolates, were found in multiple plants and designated nonplant-specific types. In addition, 10 ETs from 52 isolates were found repeatedly during different seasons. Plant-specific and nonplant-specific L. monocytogenes coexisted in processed catfish fillets. Some isolates were persistently found in processed fillets, suggesting that either the current sanitation procedures used by these plants are inadequate or that these isolates originated from the natural habitats of the catfish. The results also suggest that the repetitive element PCR is a useful tool for differentiating L. monocytogenes subtypes and can be used for tracing the source of a contamination.

scholarly journals INFLUENCE OF CARBON CONTENT ON FATIGUE STRENGTH OF DRAWN STEEL TUBES FOR SMALL ONCE-THROUGH BOILER

2012 ◽  
Vol 06 ◽  
pp. 361-366
Author(s):  
DAISUKE YONEKURA ◽  
YUTA FUJIE ◽  
RI-ICHI MURAKAMI ◽  
YUKIHIRO TOKUNAGA
Keyword(s):  
Heat Treatment ◽  
Fatigue Strength ◽  
Carbon Content ◽  
Steel Tube ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Post Heat Treatment ◽  
Steel Tubes ◽  
Heat Treated ◽  
The Difference

Tension-tension fatigue tests were performed to examine the influence of carbon content on the fatigue properties of drawn specific steel tube (STB340) with/without post heat treatment for small once-through boiler. Two different carbon content steel tubes, C =0.06 and 0.12% were prepared. The as-received, as-drawn and post drawing heat treated series for each carbon content tube were prepared for fatigue test. The hardness, grain size and residual stress were measured for each series. As a result, the fatigue strength of as-received and as-drawn series showed a small difference between C =0.06 and 0.12% specimens. However, the post drawing heat treatment series showed obvious difference in the fatigue strength. The fatigue strength of higher carbon content tubes significantly decreased by the post drawing heat treatment, whereas the decrease of fatigue strength was little for lower carbon content heat treated tubes. The difference of fatigue strength was mainly caused by the degree of relaxation of work hardening by post heat treatment.

Influence of Heat Treatment on Fatigue Strength of Drawn Steel Tubes for Small-Sized Single Pass Boiler

2011 ◽  
Vol 275 ◽  
pp. 109-112 ◽  
Author(s):  
Daisuke Yonekura ◽  
Yuta Fujie ◽  
Hayato Nishii ◽  
Hiroshi Yamakawa ◽  
Riichi Murakami
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Grain Size ◽  
Fatigue Strength ◽  
Steel Tube ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Post Heat Treatment ◽  
Single Pass ◽  
Heat Treated

Tension-tension fatigue tests were performed to examine the influence of post drawing heat treatment on the fatigue properties of drawn specific steel tube (STB340) for small-sized single pass boiler. The untreated, as-drawn and post drawing heat treated series were prepared for fatigue tests. The hardness, grain size and residual stress were measured for each series. As a result, the change of grain size and residual stress was small after post heat treatment. The drawn series was softened by post heat treatment but the hardness was still higher than untreated samples. The fatigue strength of the as-drawn and the post drawing heat treated series was higher than that of untreated series. In addition, the difference of endurance limit was small between as-drawn and post drawing heat treated series.

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