scholarly journals Inactivation of Listeria monocytogenes and Salmonella on Stainless Steel by a Piezoelectric Cold Atmospheric Plasma Generator

2021 ◽  
Vol 11 (8) ◽  
pp. 3567
Author(s):  
Cid R. Gonzalez-Gonzalez ◽  
Bethan J. Hindle ◽  
Saliha Saad ◽  
Alexandros Ch. Stratakos
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Goodness Of Fit ◽  
Low Voltage ◽  
Atmospheric Pressure Plasma ◽  
Plasma Generator ◽  
Ambient Air ◽  
Weibull Model ◽  
Atmospheric Plasma ◽  
Inactivation Kinetics

Cold atmospheric pressure plasma (CAP) is a novel non-thermal technology that is gaining increasing importance as a decontamination method. Stainless steel is a widespread food contact surface used in food-processing environments. In this study, for the first time, a low-voltage piezoelectric CAP device that uses ambient air was assessed for its antimicrobial efficiency against Salmonella and Listeria monocytogenes. These inoculated on stainless steel at different exposure times (0–300 s), two different distances (10 and 20 mm), and two different cleanliness levels (clean and protein-soiled). Two inactivation models were compared to study the inactivation kinetics of the pathogens. The results showed that CAP treatment effectively reduced L. monocytogenes and Salmonella levels. The Weibull + tail model showed better goodness of fit than the Weibull model. Protein-soiled coupons showed a protective effect to cold plasma inactivation achieving lower reductions compared to clean stainless-steel coupons for both L. monocytogenes and Salmonella. Longer distances from the plasma source decreased the decontamination efficiency of CAP; however, the difference in pathogen reduction was less pronounced at longer exposure times. This study demonstrates the capacity of a low-voltage piezoelectric CAP device to effectively reduce the levels of both foodborne pathogens on stainless-steel surfaces and the potential to adopt this technology by the food industry as a disinfection process of surfaces to reduce cross-contamination and thus increase safety.

Modeling the Inactivation of Bacillus cereus in Tiger Nut Milk Treated with Cold Atmospheric Pressure Plasma

2019 ◽  
Vol 82 (11) ◽  
pp. 1828-1836 ◽  
Author(s):  
ALIYU IDRIS MUHAMMAD ◽  
RUILING LV ◽  
XINYU LIAO ◽  
WEIJUN CHEN ◽  
DONGHONG LIU ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Atmospheric Pressure ◽  
Treatment Time ◽  
Atmospheric Pressure Plasma ◽  
Titratable Acidity ◽  
Weibull Model ◽  
Input Power ◽  
Inactivation Kinetics ◽  
Pressure Plasma ◽  
Cold Atmospheric Pressure Plasma

ABSTRACT The impact of cold atmospheric pressure plasma treatment on the inactivation kinetics of Bacillus cereus ATCC 14579 and the resulting quality changes was investigated in tiger nut (Cyperus esculentus L.) milk (TNM). The effect of input power (39, 43, and 46 W) and treatment time (0 to 270 s) was fitted using the Weibull model to represent the microbial kinetic inactivation in the treated TNM. Inactivation efficacy increased with an increase in treatment time and input power. A 5.28-log reduction was achieved at 39 to 46 W without significant changes in titratable acidity, whereas no reduction in titratable acidity was observed in the pasteurized sample. The inactivation kinetics was adequately described by the Weibull model. Higher input power of 43 and 46 W and 120 s of treatment resulted in marked decreases in pH, flavonoid concentration, and antioxidant activity compared with those parameters in pasteurized TNM. Increases in total color difference and phenolic concentrations also were observed. The results indicate that these changes were caused by the immanent plasma reactive species. This study provides valuable inactivation kinetics information for food safety assessment studies of B. cereus vegetative cells in TNM.

scholarly journals Inactivation of L. monocytogenes and S. typhimurium Biofilms by Means of an Air-Based Cold Atmospheric Plasma (CAP) System

Foods ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 157 ◽  
Author(s):  
Marlies Govaert ◽  
Cindy Smet ◽  
Annika Graeffe ◽  
James L. Walsh ◽  
Jan F. M. Van Impe
Keyword(s):  
Barrier Discharge ◽  
Ambient Air ◽  
Atmospheric Plasma ◽  
Inactivation Kinetics ◽  
Surface Barrier ◽  
Discharge System ◽  
Cold Atmospheric Plasma ◽  
Population Type ◽  
Cell Densities ◽  
Set Up

Previous (biofilm) inactivation studies using Cold Atmospheric Plasma (CAP) focused on helium (with or without the addition of oxygen) as feeding gas since this proved to result in a stable and uniform plasma. In industry, the use of helium gas is expensive and unsafe for employees. Ambient air is a possible substitute, provided that similar inactivation efficacies can be obtained. In this research, 1 and 7 day-old (single/dual-species) model biofilms containing L. monocytogenes and/or S. typhimurium cells were treated with an air-based Surface Barrier Discharge (SBD) plasma set-up for treatment times between 0 and 30 min. Afterwards, cell densities were quantified via viable plate counts, and predictive models were applied to determine the inactivation kinetics and the efficacy. Finally, the results were compared to previously obtained results using a helium-based SBD and DBD (Dielectric Barrier Discharge) system. This study has demonstrated that the efficacy of the air-based CAP treatment depended on the biofilm and population type, with log-reductions ranging between 1.5 and 2.5 log10(CFU/cm2). The inactivation efficacy was not significantly influenced by the working gas, although the values were generally higher for the air-based system. Finally, this study has demonstrated that the electrode configuration was more important than the working gas composition, with the DBD electrode being the most efficient.

Inactivation Kinetics and Virulence Potential of Salmonella Typhimurium and Listeria monocytogenes Treated by Combined High Pressure and Nisin

2010 ◽  
Vol 73 (12) ◽  
pp. 2203-2210 ◽  
Author(s):  
JINGYU GOU ◽  
HYEON-YONG LEE ◽  
JUHEE AHN
Keyword(s):  
High Pressure ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Foodborne Pathogens ◽  
Pressure Change ◽  
Weibull Model ◽  
B Value ◽  
High Pressure Processing ◽  
Inactivation Kinetics ◽  
Molecular Characteristics

The aim of this study was to characterize the physiological and molecular changes of Salmonella Typhimurium and Listeria monocytogenes in deionized water (DIW) and nisin solutions (100 IU/g) during high pressure processing (HPP). Strains of Salmonella Typhimurium and L. monocytogenes in DIW or nisin solutions were subjected to 200, 300, and 400 MPa for 20 min. The Weibull model adequately described the HPP inactivation of Salmonella Typhimurium and L. monocytogenes. Salmonella Typhimurium and L. monocytogenes populations were reduced to less than 1 CFU/ml in DIW and nisin solutions under 400 MPa. The highest b value was 5.75 for Salmonella Typhimurium in nisin solution under 400 MPa. L. monocytogenes was more sensitive to pressure change when suspended in DIW than when suspended in nisin. The pressure sensitivity of both Salmonella Typhimurium and L. monocytogenes was higher in DIW solution (141 to 243 MPa) than in nisin solution (608 to 872 MPa). No recovery of HPP-injured cells in DIW and nisin solutions treated at 400 MPa was observed after 7 days of refrigerated storage. The heterogeneity of HPP-treated cells was revealed in flow cytometry dot plots. The transcripts of stn, invA, prfA, and inlA were relatively down-regulated in HPP-treated nisin solution. The combination of high pressure and nisin could noticeably suppress the expression of virulence-associated genes. These results provide useful information for understanding the physiological and molecular characteristics of foodborne pathogens under high-pressure stress.

Inactivation Kinetics and Factors of Variability in the Pulsed Light Treatment of Listeria innocua Cells

2007 ◽  
Vol 70 (11) ◽  
pp. 2518-2525 ◽  
Author(s):  
AARON R. UESUGI ◽  
SARAH E. WOODLING ◽  
CARMEN I. MORARU
Keyword(s):  
Stainless Steel ◽  
Weibull Model ◽  
Inoculum Size ◽  
Listeria Innocua ◽  
Most Probable Number ◽  
Inactivation Kinetics ◽  
Xenon Lamp ◽  
Pulsed Light ◽  
Probable Number ◽  
Log Reduction

Pulsed light (PL) treatment can effectively reduce microbial populations in clear substrates and on surfaces, but its effectiveness varies as a function of substrate or treatment-related factors. For PL to be successfully adopted by the food industry, all factors of influence, as well as the inactivation kinetics for the microorganisms of concern, must be elucidated. In this study, the inactivation kinetics of Listeria innocua and the effect of inoculum size on PL inactivation were investigated. Stainless steel coupons (50.8 by 101.6 mm) of defined surface properties and transparent glass chamber slides (25.4 by 50.8 by 10 mm) were each inoculated with 1 ml of aqueous suspensions of L. innocua containing inoculum populations of up to 109 CFU. The thickness of the liquid layer in the glass slides was 1.16 mm. The inoculated substrates were exposed to PL treatment of up to 17 J/cm2 in a static PL chamber equipped with a pulsed Xenon lamp. Survivors were recovered and enumerated by both standard plate counting and most-probable-number procedures. The data indicated that in clear liquids, PL resulted in more than a 6-log reduction of L. innocua after a 12-J/cm2 treatment, regardless of the initial inoculum size. For the stainless steel surfaces, less than a 4-log reduction after a 12-J/cm2 treatment and a noticeable effect of substrate characteristics and inoculum size on inactivation were observed. The survivor curves showed pronounced tailing for all substrates used in the study. The Weibull model accurately predicted the survivor ratios for the PL treatment of L. innocua in clear liquids, with a shape and scale parameter of 0.33 and 3.01, respectively. The Weibull model resulted in significant overestimation of PL effectiveness for the stainless steel substrates, where the influence of various substrate properties and inoculum level on inactivation was significant.

Stripping Photo-Resist with RF Dielectric Barrier Atmospheric Pressure Plasma

2012 ◽  
Vol 260-261 ◽  
pp. 114-119 ◽  
Author(s):  
Shao Xia Jia ◽  
Ling Li Zhao ◽  
Jing Hua Yang ◽  
Chen Zhang ◽  
Shou Gou Wang
Keyword(s):  
Atmospheric Pressure ◽  
Atmospheric Pressure Plasma ◽  
Emission Spectra ◽  
Optical Emission ◽  
Plasma Generator ◽  
Ambient Air ◽  
High Energy ◽  
Optical Microscope ◽  
Dielectric Barrier ◽  
Pressure Plasma

A novel radio frequency single-dielectric-barrier-discharge atmospheric pressure plasma generator was designed and utilized to strip AZ9912 photo-resist (PR). Argon (Ar) and oxygen (O2) were employed as the working gases under atmospheric pressure in ambient air. The PR stripping rate was measured as functions of time, input power, and the flow rates of the oxygen/argon. Optical Emission Spectroscopy (OES) was used to measure the optical emission spectra of the plasma to study the mechanism of PR stripping process. It is presumable that C-H bands were broken by high energy electron in the plasma and OH was generated in the process with the participation of O atom. Optical Microscope, Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) were used to measure the surface of the silicon substrate after the stripping. It is proved that this kind of novel device could strip the AZ9912 PR effectively as high as 850nm/min, without residues and ion bombardment damage on the wafer substrate.

scholarly journals The Whitening Effect and Histological Safety of Nonthermal Atmospheric Plasma Inducing Tooth Bleaching

2021 ◽  
Vol 18 (9) ◽  
pp. 4714
Author(s):  
Seoul-Hee Nam ◽  
Byul Bo Ra Choi ◽  
Gyoo-Cheon Kim
Keyword(s):  
Alternative Energy ◽  
Soft Tissues ◽  
Inflammatory Responses ◽  
Color Change ◽  
Atmospheric Pressure Plasma ◽  
Atmospheric Plasma ◽  
Tooth Bleaching ◽  
Histological Evaluation ◽  
Light Sources ◽  
Tooth Color

Various light sources have been applied to enhance the bleaching effect. This study was to identify the histological evaluation in oral soft tissues, as well as tooth color change after tooth bleaching by nonthermal atmospheric pressure plasma (NAPP). Nine New Zealand adult female rabbits were randomly divided into three groups (n = 3): group 1 received no treatment; group 2 was treated with NAPP and 15% carbamide peroxide (CP), which contains 5.4% H2O2, and group 3 was treated with 15% CP without NAPP. Color change (ΔE) was measured using the Shade Eye NCC colorimeter. Animals were euthanized one day later to analyze the histological responses occurring in oral soft tissues, including pulp, gingiva, tongue, buccal mucosa, and hard and soft palates. Changes in all samples were analyzed by hematoxylin and eosin staining and Masson’s trichrome. Teeth treated with plasma showed higher ΔE than that obtained with bleaching agents alone. Overall, the histological characteristics observed no appreciable changes. The combinational treatment of plasma had not indicated inflammatory responses as well as thermal damages. NAPP did not cause histological damage in oral soft tissues during tooth bleaching. We suggest that NAPP could be a novel alternative energy source to conventional light sources for tooth bleaching.

scholarly journals Plasma Treatment of Fish Cells: The Importance of Defining Cell Culture Conditions in Comparative Studies

2021 ◽  
Vol 11 (6) ◽  
pp. 2534
Author(s):  
Henrike Rebl ◽  
Claudia Bergemann ◽  
Sebastian Rakers ◽  
Barbara Nebe ◽  
Alexander Rebl
Keyword(s):  
Plasma Treatment ◽  
Cell Lines ◽  
Mammalian Cells ◽  
Atmospheric Pressure Plasma ◽  
Fish Farming ◽  
Skin Lesions ◽  
Atmospheric Plasma ◽  
Fish Cell ◽  
Farmed Fish ◽  
Fish Cells

The present study provides the fundamental results for the treatment of marine organisms with cold atmospheric pressure plasma. In farmed fish, skin lesions may occur as a result of intensive fish farming. Cold atmospheric plasma offers promising medical potential in wound healing processes. Since the underlying plasma-mediated mechanisms at the physical and cellular level are yet to be fully understood, we investigated the sensitivity of three fish cell lines to plasma treatment in comparison with mammalian cells. We varied (I) cell density, (II) culture medium, and (III) pyruvate concentration in the medium as experimental parameters. Depending on the experimental setup, the plasma treatment affected the viability of the different cell lines to varying degrees. We conclude that it is mandatory to use similar cell densities and an identical medium, or at least a medium with identical antioxidant capacity, when studying plasma effects on different cell lines. Altogether, fish cells showed a higher sensitivity towards plasma treatment than mammalian cells in most of our setups. These results should increase the understanding of the future treatment of fish.

Inactivation of Surface-adherent Listeria monocytogenes Hypochlorite and Heat

1991 ◽  
Vol 54 (1) ◽  
pp. 4-6 ◽  
Author(s):  
SHIN-HO LEE ◽  
JOSEPH F. FRANK
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Cell Population ◽  
Incubation Time ◽  
Cell Populations ◽  
Adherent Cell ◽  
Adherent Cells ◽  
D Cells

Inactivation by hypochlorite of Listeria monocytogenes cells adherent to stainless steel was determined. Adherent cell populations were prepared by incubating stainless steel slides with a 24 h culture of L. monocytogenes for 4 h at 21°C. Adherent microcolonies were prepared by growing L. monocytogenes on stainless steel slides submerged in a 1:15 dilution of tryptic soy broth at 21°C. The slides were then rinsed and transferred to fresh sterile broth every 2 d with a total incubation time of 8 d. Although the 4 h and 8 d adherent populations were at similar levels, 8 d adherent cells were over 100 times more resistant than the 4 h adherent cell population when exposed to 200 ppm hypochlorite for 30 s. When stainless steel slides containing adherent cells were heated at 72°C both adherent cell populations were inactivated after 1 min. Detectable numbers of L. monocytogenes remained on stainless steel slides after treatment at 65°C for 3 min when adherent 8 d cells were tested but not when adherent 4 h cells were used.

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