scholarly journals Listeria monocytogenes Attachment to and Detachment from Stainless Steel Surfaces in a Simulated Dairy Processing Environment

2009 ◽  
Vol 75 (22) ◽  
pp. 7182-7188 ◽  
Author(s):  
Sofia Poimenidou ◽  
Charalambia A. Belessi ◽  
Efstathios D. Giaouris ◽  
Antonia S. Gounadaki ◽  
George-John E. Nychas ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Food Processing ◽  
Dairy Products ◽  
Pasteurized Milk ◽  
Fresh Milk ◽  
Dairy Processing ◽  
Two Temperatures ◽  
Steel Surfaces ◽  
Suspended Cells

ABSTRACT The presence of pathogens in dairy products is often associated with contamination via bacteria attached to food-processing equipment, especially from areas where cleaning/sanitation is difficult. In this study, the attachment of Listeria monocytogenes on stainless steel (SS), followed by detachment and growth in foods, was evaluated under conditions simulating a dairy processing environment. Initially, SS coupons were immersed in milk, vanilla custard, and yogurt inoculated with the pathogen (107 CFU/ml or CFU/g) and incubated at two temperatures (5 and 20�C) for 7 days. By the end of incubation, cells were mechanically detached from coupons and used to inoculate freshly pasteurized milk which was subsequently stored at 5�C for 20 days. The suspended cells in all three products in which SS coupons were immersed were also used to inoculate freshly pasteurized milk (5�C for 20 days). When SS coupons were immersed in milk, shorter lag phases were obtained for detached than for planktonically grown cells, regardless of the preincubation temperature (5 or 20�C). The opposite was observed when custard incubated at 20�C was used to prepare the two types of inocula. However, in this case, a significant increase in growth rate was also evident when the inoculum was derived from detached cells. In another parallel study, while L. monocytogenes was not detectable on SS coupons after 7 days of incubation (at 5�C) in inoculated yogurt, marked detachment and growth were observed when these coupons were subsequently transferred and incubated at 5�C in fresh milk or/and custard. Overall, the results obtained extend our knowledge on the risk related to contamination of dairy products with detached L. monocytogenes cells.

Survival of Listeria monocytogenes Attached to Stainless Steel Surfaces in the Presence or Absence of Flavobacterium spp.

2001 ◽  
Vol 64 (9) ◽  
pp. 1369-1376 ◽  
Author(s):  
PHILIP J. BREMER ◽  
IAN MONK ◽  
CAROLYN M. OSBORNE
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Mixed Culture ◽  
Cell Population ◽  
Exposure Time ◽  
Food Processing ◽  
Pure Culture ◽  
Bacterial Biofilm ◽  
Selective Agar ◽  
Steel Surfaces

Contaminated surfaces of food processing equipment are believed to be a significant source of Listeria monocytogenes to foods. However, very little is known about the survival of Listeria in processing environments. In a mixed bacterial biofilm of L. monocytogenes and Flavobacterium spp., the number of L. monocytogenes cells attaching to stainless steel increased significantly compared to when L. monocytogenes was in a pure culture. The L. monocytogenes cells in the mixed biofilms were also recoverable for significantly longer exposure periods. On colonized coupons held at 15°C and 75% humidity, decimal reduction times were 1.2 and 18.7 days for L. monocytogenes in pure and mixed biofilms, respectively. With increasing exposure time, the proportion of cells that were sublethally injured (defined as an inability to grow on selective agar) increased from 8.1% of the recoverable cell population at day 0 to 91.4% after 40 days' exposure. At 4 and −20°C, decimal reduction times for L. monocytogenes in pure culture were 2.8 and 1.4 days, respectively, and in mixed culture, 10.5 and 14.4 days, respectively. The enhanced colonization and survival of L. monocytogenes on “unclean” surfaces increase the persistence of this pathogen in food processing environments, while the increase in the percentage of sublethally injured cells in the population with time may decrease the ability of enrichment regimes to detect it.

Persistent Listeria monocytogenes Strains Show Enhanced Adherence to Food Contact Surface after Short Contact Times

2000 ◽  
Vol 63 (9) ◽  
pp. 1204-1207 ◽  
Author(s):  
JANNE M. LUNDÉN ◽  
MARIA K. MIETTINEN ◽  
TIINA J. AUTIO ◽  
HANNU J. KORKEALA
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Contact Surface ◽  
Food Processing ◽  
Contact Time ◽  
Ice Cream ◽  
Short Contact ◽  
Steel Surfaces ◽  
Food Contact Surface ◽  
Epifluorescence Microscope

Adherence of 3 persistent and 14 nonpersistent Listeria monocytogenes strains to stainless steel surfaces after short and long contact times was investigated. L. monocytogenes strains were obtained from poultry plants and an ice cream plant throughout several years. Adherence tests were performed in tryptic soy broth at 25°C for 1, 2, and 72 h. Test surfaces were rinsed after the contact time, and attached cells were stained with acridine orange and enumerated with an epifluorescence microscope. The persistent poultry plant strains showed adherence 2- to 11-fold higher than the nonpersistent strains following 1- and 2-h contact times. The adherence of the persistent ice cream plant strain after 1- and 2-h contact times was higher than most of the nonpersistent strains. Seven of 12 nonpersistent ice cream strains showed an adherence of less than half that of the persistent strain. After 72 h, the differences in adherence were not as marked, since half the nonpersistent strains had reached adherence levels comparable with the persistent strains. In fact, three nonpersistent strains showed even higher adherence than the persistent strains. Thus, results of this study reveal that persistent L. monocytogenes strains show enhanced adherence at short contact times, promoting their survival in food processing facilities and possibly having an effect on initiation of persistent plant contamination.

Occurrence of Listeria monocytogenes in Milk and Dairy Products Produced or Imported Into Morocco

1993 ◽  
Vol 56 (3) ◽  
pp. 256-259 ◽  
Author(s):  
A. EL MARRAKCHI ◽  
A. HAMAMA ◽  
F. EL OTHMANI
Keyword(s):  
Listeria Monocytogenes ◽  
Dairy Products ◽  
Raw Milk ◽  
Listeria Innocua ◽  
Pasteurized Milk ◽  
Listeria Species ◽  
Fresh Cheese ◽  
Milk And Dairy Products

Examination of 227 samples of milk and dairy products for Listeria monocytogenes showed that raw milk and some Moroccan traditionally made dairy products such as Iben and raib (fermented milks) and jben (fresh cheese) were contaminated with this pathogen. L. monocytogenes was the only Listeria species isolated except in one case in which it was associated with Listeria innocua. Pasteurized milk, fresh cream, and fresh and ripened cheeses (industrially made) were free from L. monocytogenes.

scholarly journals Comparison of three neutralizing broths for environmental sampling of low levels of Listeria monocytogenes desiccated on stainless steel surfaces and exposed to quaternary ammonium compounds

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Fengmin Li ◽  
Zhihan Xian ◽  
Hee Jin Kwon ◽  
Jiyoon Yoo ◽  
Laurel Burall ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Quaternary Ammonium ◽  
Storage Conditions ◽  
Ammonium Compound ◽  
Environmental Sampling ◽  
High Concentration ◽  
Environmental Test ◽  
Steel Surfaces ◽  
Low Levels

Abstract Background An effective environmental sampling method involves the use of a transport/neutralizing broth with the ability to neutralize sanitizer residues that are collected during sampling and to maintain viability of stressed Listeria monocytogenes (Lm) cells. Results We applied Lm onto stainless steel surfaces and then subjected Lm to desiccation stress for 16–18 h at room temperature (RT, 21–24 °C). This was followed by the subsequent application of Whisper™ V, a quaternary ammonium compound (QAC)-based sanitizer, diluted to 400 ppm and 8000 ppm of active quat, for 6 h. We then sampled Lm with sponges pre-moistened in three transport broths, Dey/Engley (D/E) broth, Letheen broth and HiCap™ broth, to generate environmental samples that contained sanitizer residues and low levels of stressed Lm, which were subsequently analyzed by an enrichment-based method. This scheme conformed with validation guidelines of AOAC International by using 20 environmental test portions per broth that contained low levels of Lm such that not all test portions were positive (i.e., fractional positive). We showed that D/E broth, Letheen broth and HiCap™ broth performed similarly when no quat or 400 ppm of quat was applied to the Lm contaminating stainless steel surfaces. However, when 8000 ppm of quat was applied, Letheen broth did not effectively neutralize the QAC in the samples. These comparisons were performed on samples stored under three conditions after collection to replicate scenarios of sample transport, RT for 2 h, 4 °C for 24 h and 4 °C for 72 h. Comparisons under the three different scenarios generally reached the same conclusions. In addition, we further demonstrated that storing Letheen and HiCap™ broths at RT for two months before sampling did not reduce their capacity to neutralize sanitizers. Conclusions We developed a scheme to evaluate the ability of transport broths to neutralize QAC sanitizers. The three transport broths performed similarly with a commonly used concentration of quat, but Letheen broth could not effectively neutralize a very high concentration of QAC. The performance of transport broths was not significantly affected under the assessed pre-sampling and post-sampling storage conditions.

Nanoengineered Superhydrophobic Surfaces to Prevent Adhesion of Listeria monocytogenes for Improved Food Safety

2020 ◽  
Vol 63 (5) ◽  
pp. 1401-1407
Author(s):  
Bog Eum Lee ◽  
Youngsang You ◽  
Won Choi ◽  
Eun-mi Hong ◽  
Marisa M. Wall ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Biofilm Formation ◽  
Electrochemical Etching ◽  
Contact Angles ◽  
Bacterial Attachment ◽  
Superhydrophobic Surfaces ◽  
List Type ◽  
Ptfe Film ◽  
Steel Surfaces

HighlightsNanoporous superhydrophobic surfaces were fabricated using electrochemical etching and Teflon coating.Adhesion of Listeria monocytogenes to the nanoengineered stainless steel surfaces was reduced.Self-cleanable food-contact surfaces prevent bacterial attachment and subsequent biofilm formation.Abstract. Bacterial attachment on solid surfaces and subsequent biofilm formation is a significant problem in the food industry. Superhydrophobic surfaces have potential to prevent bacterial adhesion by minimizing the contact area between bacterial cells and the surface. In this study, stainless steel-based superhydrophobic surfaces were fabricated by manipulating nanostructures with electrochemical etching and polytetrafluoroethylene (PTFE) film. The formation of nanostructures on stainless steel surfaces was characterized by field emission scanning electron microscopy (FESEM). The stainless steel surfaces etched at 10 V for 5 min and at 10 V for 10 min with PTFE deposition resulted in average water contact angles of 154° ±4° with pore diameters of 50 nm. In addition, adhesion of Listeria monocytogenes was decreased by up to 99% compared to the bare substrate. These findings demonstrate the potential for the development of antibacterial surfaces by combining nanoporous patterns with PTFE films. Keywords: Electrochemical etching, PTFE, Nanoengineered surface, L. monocytogenes, Superhydrophobic.

scholarly journals Variable Adhesion of Listeria monocytogenes Isolates from Food-Processing Facilities and Clinical Cases to Inert Surfaces

2007 ◽  
Vol 70 (7) ◽  
pp. 1569-1578 ◽  
Author(s):  
ODILE TRESSE ◽  
KELLY SHANNON ◽  
ANTHONY PINON ◽  
PIERRE MALLE ◽  
MICHÈLE VIALETTE ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Food Processing ◽  
Microtiter Plate ◽  
Clinical Strains ◽  
Microtiter Plates ◽  
Industrial Strains ◽  
Cheese Industry ◽  
Adhesion Rate ◽  
Inert Surfaces

One hundred one strains of Listeria monocytogenes isolated from seafood and cheese industry samples and from patients with listeriosis were assessed using a microtiter plate method for adhesion to polystyrene and stainless steel surfaces. The adhesion rate for these strains ranged from 3.10 to 35.29% with an inoculum of 8 × 108 cells per well. A strong correlation was found between adhesion to polystyrene and stainless steel microtiter plates, indicating that the intrinsic ability of L. monocytogenes to adhere to inert surfaces is stronger than the influence of the surface's physicochemical properties. The clinical strains were less adherent to inert surfaces than were the industrial strains. By integrating other factors such as location of the industrial strains, contamination type of the clinical strains, serotype, and pulsotype into the analysis, some weak but significant differences were noted. For the industrial isolates, the number of cells attached to both surfaces differed significantly depending on whether they were isolated from food or food-processing environments in the seafood and cheese industry. For clinical isolates, sporadic strains exhibited greater adhesion to polystyrene than did epidemic strains. Strains belonging to the pulsed-field gel electrophoretype clusters A and M (lineages II and I, respectively) were less able to adhere to polystyrene and stainless steel than were strains in the more common clusters.

Effect of Growth Nutrients on Attachment of Listeria monocytogenes To Stainless Steel

1994 ◽  
Vol 57 (8) ◽  
pp. 720-724 ◽  
Author(s):  
KWANG Y. KIM ◽  
JOSEPH F. FRANK
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Cell Surface ◽  
Minimal Medium ◽  
Cell Attachment ◽  
Chloride Concentration ◽  
Fold Increase ◽  
Hydrolyzed Protein ◽  
Steel Surfaces ◽  
Attachment Ability

Listeria monocytogenes cells grown in chemically defined minimal medium (D10), tryptic soy broth (TSB), and modifications of these media were used to determine the effect of growth nutrients on attachment ability. Stainless steel surfaces were submerged in various cell suspensions at 21°C for 4 h, and the numbers of attached cells were compared. Cells grown in D10 showed approximately 50-fold higher attachment than those grown in TSB. Addition of components of D10 to TSB did not affect the attachment ability of cells grown in TSB. The only modifications of D10, which affected attachment ability were a 10-fold increase of ammonium chloride concentration and a 1/10 reduction in iron, both of which resulted in decreases in attachment ability to one third of the D10 control. Replacement of glucose in D10 with mannose, cellobiose, fructose or trehalose did not effect cell attachment. Replacement of nitrogen components in D10 with tryptone decreased cell attachment to the equivalent level of cells grown in TSB. The reduced attachment ability of TSB-grown cells was not the result of hydrolyzed protein absorbing to the cell surface.

Effectiveness of a Novel Rechargeable Polycationic N-Halamine Antibacterial Coating on Listeria monocytogenes Survival in Food Processing Environments

2020 ◽  
Vol 83 (11) ◽  
pp. 1974-1982
Author(s):  
GERARDO MEDINA ◽  
HARSHITA CHAUDHARY ◽  
YANG QIU ◽  
YUCHEN NAN ◽  
ARGENIS RODAS-GONZÁLEZ ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Surface Condition ◽  
Organic Load ◽  
Log Reduction ◽  
Food Contact Surfaces ◽  
Roast Beef ◽  
Steel Surfaces ◽  
The Difference ◽  
Steel Coupon

ABSTRACT The goal of this research was to evaluate the efficacy of a novel rechargeable nonleaching polycationic N-halamine coating applied to stainless steel food contact surfaces to reduce Listeria monocytogenes contamination on ready-to-eat (RTE) foods. Four L. monocytogenes strains were inoculated onto the charged (C; chlorine activated) or noncharged (NC) N-halamine–coated steel coupon surfaces that were either intact or scratched. After inoculation, test surfaces were incubated at 2, 10, and 25°C for 0, 48, and 72 h. L. monocytogenes transfer from coated adulterated surfaces to RTE meat (beef sausages and roast beef) was also tested at 2°C. L. monocytogenes on both intact-C and scratched-C surfaces was significantly reduced at all temperatures; however, in the presence of organic material, these coatings were more effective for reducing L. monocytogenes at 2 and 10°C than at 25°C (P < 0.05). In contrast, on NC intact and scratched surfaces, reduction at 25°C increased (P < 0.05), decreasing the difference in L. monocytogenes levels between charged and noncharged intact and scratched surfaces at this temperature. Overall, greater L. monocytogenes reduction was achieved on intact-C and scratched-C (4.1 ± 0.19 log CFU/cm2) than on intact-NC and scratched-NC (2.3 ± 0.19 log CFU/cm2) surfaces at all temperatures (P < 0.05). The combination of surface condition and chlorine with coupons exposed for 2 h at 2°C in the presence of an organic load (50% meat purge) did not significantly affect the bactericidal efficacy of the N-halamine coating. Regarding transfer to RTE meat, an overall 3.7-log reduction in L. monocytogenes was observed in sausages and roast beef. These findings suggest that a novel rechargeable N-halamine coating on stainless steel surfaces can inactivate L. monocytogenes. HIGHLIGHTS

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