• Journal of Food Hygiene and Safety
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• v.23 no.4
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• pp.309-313
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• 2008

To investigate the antibacterial activity of the traditional bronze alloy Yugi, the cultures of Salmonella spp., Escherichia coli O157, Enterobacter sakazakii, and Bacillus cereus were exposed to the metal coupons of bronze, copper, tin, and stainless steel, and the sterilizing activities were analyzed. Antibacterial efficacy of copper coupon toward S. Typhimurium, E. coli, and E. sakazakii were the highest among them and those were followed by bronze, tin, and then stainless steel in the activity order. However, there was little sterilizing activity on Gram-positive B. cereus. Minimal inhibitory concentrations of cupric ion were 25 ppm for S. Typhimurium, E. coli, and E. sakazakii, and 50 ppm for B. cereus. Yugi bronze alloy showed more rigidity and practicality in comparison with copper, and has been used in Korea. Therefore, the bronze alloy may be more effective to reduce the cross-contamination of S. Typhimurium, E. coli, and E. sakazakii than stainless steel in food processing surface.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.272-278
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• 2013

To evaluate the effect of surface contaminated with Escherichia coli O157:H7 (E. coli O157:H7) on the microbiological safety of lettuce, this study was conducted to investigate the attachment, biofilm producing, survival, and cross-contamination of E. coli O157:H7 on stainless steel and polyvinyl chloride (PVC). The attachment rate of E. coli O157:H7 on PVC was 10 times higher than that on stainless steel after exposure 1 h in cell suspension. However, there was not a difference between two types of surface after exposure for 6 h and 24h. The biofilm producing of E. coli O157:H7 was TSB > 10% lettuce extracts > 1% lettuce extracts > phosphate buffer. When two kinds of materials were stored at various conditions ($20^{\circ}C$ and $30^{\circ}C$, relative humidity (RH) 43%, 69%, and 100%), the numbers of E. coli O157:H7 at $30^{\circ}C$, RH 43% or RH 69% were reduced by 5.0 log CFU/coupon within 12 h regardless of material type. Conversely, the survival of E. coli O157:H7 at RH 100% was lasted more than 5 days. In addition, the reduction rate of E. coli O157:H7 was decreased in the presence of organic matter. The transfer efficiency of E. coli O157:H7 from the contaminated surface to lettuce was dependent upon the water amount of the surface of lettuce. Especially, the transfer rate of E. coli O157:H7 was increased by 10 times in the presence of water on the lettuce surface. From this study, the retention of E. coli O157:H7 on produce contact surfaces increase the risk cross-contamination of this pathogen to produce. Thus, it is important that the surface in post harvest facility is properly washed and sanitized after working for prevention of cross-contamination from surface.

• Journal of Microbiology and Biotechnology
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• v.29 no.8
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• pp.1177-1183
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• 2019

Grapefruit seed extract (GSE) is a safe and effective preservative that is used widely in the food industry. However, there are few studies addressing the anti-biofilm effect of GSE. In this study, the anti-biofilm effect of GSE was investigated against biofilm-forming strains of Staphylococcus aureus and Escherichia coli. The GSE minimum inhibitory concentration (MIC) for S. aureus and E. coli were $25{\mu}g/ml$ and $250{\mu}g/ml$, respectively. To investigate biofilm inhibition and degradation effect, crystal violet assay and stainless steel were used. Biofilm formation rates of four strains (S. aureus 7, S. aureus 8, E. coli ATCC 25922, and E. coli O157:H4 FRIK 125) were 55.8%, 70.2%, 55.4%, and 20.6% at $1/2{\times}MIC$ of GSE, respectively. The degradation effect of GSE on biofilms attached to stainless steel coupons was observed (${\geq}1$ log CFU/coupon) after exposure to concentrations above the MIC for all strains and $1/2{\times}MIC$ for S. aureus 7. In addition, the specific mechanisms of this anti-biofilm effect were investigated by evaluating hydrophobicity, auto-aggregation, exopolysaccharide (EPS) production rate, and motility. Significant changes in EPS production rate and motility were observed in both S. aureus and E. coli in the presence of GSE, while changes in hydrophobicity were observed only in E. coli. No relationship was seen between auto-aggregation and biofilm formation. Therefore, our results suggest that GSE might be used as an anti-biofilm agent that is effective against S. aureus and E. coli.

• Journal of Food Hygiene and Safety
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• v.36 no.5
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• pp.430-439
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• 2021

Essential oils with excellent antibacterial activity were used to study the inhibitory effect against the six types of food poisoning biofilms formed on the surfaces of polyethylene (PE) and stainless steel (SS) that are widely used for food processing instruments and containers. The antibacterial activity of 20 kinds of essential oils was tested using the disk diffusion method. The result showed the degree of antibacterial activity in the following order: cinnamon> clove> lemongrass> peppermint> pine needle (highest to lowest). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of cinnamon and clove oil were in the range of 0.63-1.25 mg/mL and 1.25-2.50 mg/mL, respectively. The MIC and MBC of lemongrass oil were 1.25-2.50 mg/mL and 2.50-5.00 mg/mL, respectively, showing slightly less antibacterial activity. Although the preventive effect of three types of essential oils on the biofilm formation differed slightly depending on food poisoning bacteria, PE, and SS, it was found that the precoating of 0.5% cinnamon, clove, and lemongrass oil on the PE and SS affects the formation of biofilm. Increased essential oil concentration significantly inhibited the biofilm formation for all food poisoning bacteria (P<0.05), and biofilms of Listeria monocytogenes and Staphylococcus aureus were not formed when treated with 0.5% cinnamon and clove oil. The elimination effect of food poisoning bacteria biofilms formed on the surfaces of PE and SS differed depending on the type of food poisoning bacteria. Still, the biofilm elimination effect increased as the essential oil concentration increased, and the biofilm elimination rate of clove oil was generally high. Therefore, this study found that the cinnamon and clove essential oils (0.5%) are suitable natural materials that effectively prevent, inhibit, and remove the biofilms formed by the food poisoning bacteria on the surfaces of polyethylene and stainless steel.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.260-265
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• 2002

Microbiologically influenced Corrosion (MIC) is one of the most deleterious effects of metal microbe interactions. When a fresh metal surface comes in contact with a non-sterile fluid, biofilm formation is ensued. This might result in the initiation of corrosion. The sites and materials where MIC is implicated are versatile. Industries such as shipping, power generation, chemical etc are reported to be affected. The rapid and unexpected failure of AISI type 304 stainless steel was investigated in the laboratory by simulation studies for a period of 4 months. Slime and water samples from the failure site were screened for corrosion causing bacteria. Both aerobic and anaerobic nora were enumerated and identified using PCR techniques. Pseudomonas sp. and Bacillus sp. were the most common aerobic bacteria isolated from the water and slime samples, whilst sulfate reducing bacteria (SRB) were the major anaerobic bacteria. The aerobic bacteria were used for the corrosion experiments in the laboratory. Coupon exposure studies were conducted using a very dilute (0.1%V/V) nutrient broth medium. The coupons after retrieval were observed under a Scanning Electron Microscope (SEM) for the presence of MIC pits. Compared to sterile controls, metal coupons exposed to Pseudomonas sp and Bacillus sp. showed the initiation of severe pitting corrosion. However, amongst these two strains, Psudomonas sp. caused pits in a very short span of 14 days. Towards the end of the experiment, severe pitting was observed in both the cases. The detailed observation of pits showed they vary both in number and shapes. Whilst the coupons exposed to Bacillus sp. showed widely spread scales like pits, those exposed to Pseudomonas sp. showed smaller and circular pits, which had grown in number and size by the end of the experiment. From these results it is inferred that the rapid and unexpected failure of 304 SS might be due to MIC. Pseudonwnas sp. could be considered as the major responsible bacteria that could initiate pits in the metallic structures. As the appearance of pits was different in both the tested strains, it was thought that the mechanisms of pit formation are different. Experiments on these lines are being continued.

• Journal of Food Hygiene and Safety
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• v.37 no.4
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• pp.285-295
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• 2022

The ability of volatile components of essential oils (EO) from cinnamon, clove, and lemongrass to inhibit biofilms formed on polyethylene and stainless steel by six types of food poisoning bacteria was investigated. The main components of cinnamon EO were identified as cinnamaldehyde (38.30%), linalool (9.61%), β-caryophyllene (8.90%), and 1,3,4-eugenol (8.19%). 1,3,4-Eugenol (61.84%) was the dominant component of clove EO. The major component of lemongrass EO was citral. Citral is a natural mixture of two isomeric acyclic monoterpene aldehydes: geranial (trans-citral, 19.11%) and neral (cis-citral, 19.23%). Among these major compounds, cinnamaldehyde, linalool, eugenol, and citral exhibited comparatively strong antimicrobial activity in the disc diffusion assay. Treatments with 0.1% eugenol and citral were highly effective on biofilm inhibition on both tested surfaces. Cinnamaldehyde (0.1%) was effective against biofilm formation by Listeria monocytogenes ATCC 19112 and Staphylococcus aureus KCCM 11812. These results suggested the potential of cinnamaldehyde, eugenol, and citral treatments in inhibiting the formation of biofilms by food poisoning bacteria.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.258-266
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• 2011

Scale induced by hardness materials in water must be controled because of it can be result in remarkable damages of pipeline as well as water quality deterioration. Especially hot water system is one of scale management required facility as scale formation can be accelerated by temperature. The scale control performance of frequency driver (FD) was tested instead of existing methods such as chemical, physical and electromagnetic methods which needs chemicals and electric power. Three kinds of pipe coupons were submerged in test water with 500 mg/L of hardness for 33 days and XRD and SEM were analysed for comparing scale formation characteristics of these coupons. Calcite ($CaCO_3$) which came from hardness of water was formed on only cast iron pipe coupon and this coupon showed higher corrosion rate than copper and stainless steel pipe coupon. Hot water circulating system connected cast iron pipe with and without FD was operated with 300 mg/L of hardness water at $50^{\circ}C$ for monitoring of scale formation and water quality with and without FD. XRD showed that FD leaded to magnetite ($Fe_3O_4$) scale which is good scale for preventing corrosion than calcite and SEM image also indicated the scale control effect of FD. Scales of 16% on pipe joint, 14% on pipe length, and 42% on heat exchanger decreased with FD comparing scales of those parts without FD. From the results of water quality, FD reduced crystallization of hardness material without chemical reaction in water and it can indicate that FD is safe and proenvironmental technology for scale reduction.

• Journal of Environmental Health Sciences
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• v.39 no.3
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• pp.279-288
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• 2013

Objectives: Effectiveness and conditions of vapor-phase hydrogen peroxide (VPHP) system on decontamination of Geobacillus stearothermophilus(GS) spores, Escherichia coli (E.coli) and Enterobacteria phage felix01 (felix01) were determined. Methods: The VPHP system was designed to vaporize 35% (w/w) solution of hydrogen peroxide, continuously to inject and withdraw VPHP. The system and VHP 1000ED (Steris) were operated such that dehumidification and conditioning were initiated without samples in the chamber. Then the samples were loaded into and removed. Coupons (glass, anodizing, silicon, viton) with GS spores ($1{\times}10^6$ colony forming unit/mL [CFU/mL]), E.coli ($1{\times}10^7$ CFU/mL) and felix01 ($1{\times}10^7$ plaque forming unit/mL[PFU/mL]), and Biological Indicator (BI) with GS spores ($1{\times}10^6$ CFU/mL) on stainless steel coupons were used. The tested samples were sonicated and vortexed, and then were plated for enumeration, followed by incubation at $55^{\circ}C$, 24 hr for GS spores, and at $37^{\circ}C$, 24 hr for E.coli and felix01. BI analysis in broth culture was only qualitative. Results: The efficacy of the VPHP system on decontamination was almost equivalent to that of VHP 1000ED. The conditions for complete decontamination with the VPHP system was as follows: concentration; 700~450 ppm, relative humidity; approximately 55%, and temperature; $34{\sim}32^{\circ}C$. When comparing the decontamination efficiency among different kinds of coupons, glass was the most effective, however, all kinds of coupons were decontaminated completely after 60 min exposure in both systems. Conclusion: The VPHP system can be recommended as an alternative system for traditional system using ethylene oxide, formaldehyde or chlorine dioxide.

• Journal of Biosystems Engineering
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• v.40 no.2
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• pp.145-152
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• 2015

Purpose: The inability to adequately judge the efficacy of cleaning and sanitation procedures in deli departments is a recognized food safety concern. In a prior study, our research group demonstrated that visual inspection of cleaned produce processing surfaces could be enhanced through the use of a portable fluorescence imaging device that detected residual produce residues. Methods: To explore the feasibility of using fluorescence imaging to similarly detect residual deli residues, spectra of American, Cheddar, Provolone, and Swiss cheeses and of processed chicken, ham, roast beef, and turkey were acquired using a laboratory hyperspectral imaging system. Circular punches of these commodities were placed onto stainless steel and high density polyethylene coupons for imaging. The coupon materials were selected to represent common surfaces found in deli departments. Results: Analysis of hyperspectral fluorescence images showed that cheeses exhibited peaks in the blue-green region and at around 675 nm. Meats exhibited peaks in the blue-green region with one of four ham and one of four chicken brands exhibiting peaks at around 675 nm, presumably due to use of plant-derived additives. When commodities were intermittently imaged over two weeks, locations of spectral peaks were preserved while intensity of peaks at shorter wavelengths increased with time. Conclusion: These results demonstrate that fluorescence imaging techniques have the potential to enhance surface hygiene inspection in deli departments and, given the immediate availability of imaging results, to help optimize routine cleaning procedures.