Effects of Inoculation Level, Material Hydration, and Stainless Steel Surface Roughness on the Transfer of Listeria monocytogenes from Inoculated Bologna to Stainless Steel and High-Density Polyethylene

2007 ◽  
Vol 70 (6) ◽  
pp. 1423-1428 ◽  
Author(s):  
ANDRÉS RODRÍGUEZ ◽  
WESLEY R. AUTIO ◽  
LYNNE A. McLANDSBOROUGH
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
High Density Polyethylene ◽  
Steel Surface ◽  
Testing Machine ◽  
High Density ◽  
Stainless Steel Surface ◽  
Material Type ◽  
The Absolute

The influence of inoculation level, material hydration, and stainless steel surface roughness on the transfer of Listeria monocytogenes from inoculated bologna to processing surfaces (stainless steel and polyethylene) was assessed. Slices of bologna (14 g) were inoculated with Listeria at different levels, from 105 to 109 CFU/cm2. Transfer experiments were done at a constant contact time (30 s) and pressure (45 kPa) with a universal testing machine. After transfer, cells that had been transferred to sterile stainless steel and polyethylene were removed and counted, and the efficiency of transfer (EOT) was calculated. As the inoculation level increased from 105 to 109 CFU/cm2, the absolute level of transfer increased in a similar fashion. By calculating EOTs, the data were normalized, and the initial inoculation level had no effect on the transfer (P > 0.05). The influence of hydration level on stainless steel, high-density polyethylene, and material type was investigated, and the EOTs ranged from 0.1 to 1 under all the conditions tested. Our results show that transfers to wetted processing surfaces (mean EOT = 0.43) were no different from dried processing surfaces (mean EOT = 0.35) (P > 0.05). Material type was shown to be a significant factor, with greater numbers of Listeria transferring from bologna to stainless steel (mean EOT = 0.49) than from bologna to polyethylene (mean EOT = 0.28) (P < 0.01). Stainless steel with three different surface roughness (Ra) values of <0.8 μm (target Ra = 0.25, 0.50, and 0.75 μm) and two different finishes (mechanically polished versus mechanically polished and further electropolished) was used to evaluate its effect on the transfer. The surface roughness and finish on the stainless steel did not have any effect on the transfer of Listeria (P > 0.05). Our results showed that when evaluating the transfer of Listeria, the use of EOTs rather than the absolute transfer values is essential to allow comparisons of transfer conditions or comparisons between research groups.

Evaluation of the Transfer of Listeria monocytogenes from Stainless Steel and High-Density Polyethylene to Bologna and American Cheese

2007 ◽  
Vol 70 (3) ◽  
pp. 600-606 ◽  
Author(s):  
ANDRÉS RODRÍGUEZ ◽  
LYNNE A. McLANDSBOROUGH
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
High Density Polyethylene ◽  
Testing Machine ◽  
High Density ◽  
Food Type ◽  
Biofilm Growth ◽  
Type Stainless Steel ◽  
Steel Surfaces ◽  
The Impact

The objective of this study was to determine the factors involved in the transfer of Listeria monocytogenes from surfaces to foods. We evaluated the influence of surface type (stainless steel and high-density polyethylene), inoculation method (biofilm growth and attached cells), hydration level (visibly dry and wet), and food type (bologna and American cheese). Each experiment included all 16 combinations and was repeated 11 times. A four-strain cocktail of L. monocytogenes was used to inoculate stainless steel and high-density polyethylene either as growing biofilms or attached cells. Slides were placed on a universal testing machine and brought into contact with food at a constant pressure (45 kPa) and time (30 s). Food slices were blended, the number of transferred cells was determined by plating, and the efficiency of transfer (EOT) was calculated. The results strongly suggest that stainless steel surfaces transferred more L. monocytogenes to foods than did polyethylene (P = 0.05). Independent of the surface, biofilms tended to transfer more L. monocytogenes to foods (EOT = 0.57) than did attached cells (EOT = 0.16). Among foods, L. monocytogenes was transferred to bologna more easily than to cheese (P < 0.05). The impact of hydration on transfer was significantly higher for dried biofilms growing on stainless steel (P < 0.05). No significant differences for hydration were seen under other conditions (P > 0.05). We hypothesize that drying weakens cell-to-cell interactions in biofilms and cell-to-surface interactions of biofilms and thus allows increased transfer of cells to food products.

Effect of Alkaline Treatment on Sawdust Reinforced High Density Polyethylene Composite under Wide Strain Rate

2016 ◽  
Vol 840 ◽  
pp. 103-107 ◽  
Author(s):  
Haliza Jaya ◽  
Mohd Firdaus Omar ◽  
Hazizan Md Akil ◽  
Zainal Arifin Ahmad ◽  
Nik Noriman Zulkepli
Keyword(s):  
Surface Roughness ◽  
Strain Rate ◽  
Dynamic Loading ◽  
High Density Polyethylene ◽  
Split Hopkinson Pressure Bar ◽  
Alkali Treatment ◽  
Testing Machine ◽  
High Density ◽  
Rate Condition ◽  
Static And Dynamic Loading

In this study, the alkali treatment of sawdust using different concentration of sodium hydroxide (NaOH) is performed. The purpose of this treatment is to improve the filler-matrix compatibility, thus, enhance the properties of tested specimens under various strain rate condition. The outcome shows the alkali treated sawdust did improve its surface roughness through reduction of sawdust diameter. With this increasing of surface roughness, it will enhance the compatibility between sawdust filler and HDPE matrix. For comparison purpose, the treated and untreated sawdust filler were reinforce in High Density Polyethylene (HDPE) matrix and have been test under static and dynamic loading using Universal Testing Machine (UTM) and Split Hopkinson Pressure Bar (SHPB) apparatus. The results indicate that the stiffness and compression strength properties were improved on treated sawdust composites for both static and dynamic loading compare to untreated sawdust composites.

scholarly journals Characteristic features of Enterococcus faecalis film formation on the stainless steel AISI 321 depending on the surface roughness

2018 ◽  
Vol 20 (90) ◽  
pp. 58-62
Author(s):  
K. U. Kravcheniuk
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Enterococcus Faecalis ◽  
Steel Surface ◽  
Film Formation ◽  
High Density ◽  
Initial Number ◽  
Steel Aisi ◽  
Aisi 321 ◽  
Stainless Steel Aisi

At the present stage of milk products manufacture, the most important factor affecting their safety and reducing their storage time is a microbiological one. Despite all complex of measures including washing, disinfection, heat processing to eliminate microbes on production equipment and in the finished products it is very difficult to achieve good results. This deals with the fact that microorganisms can survive on the production equipment thanks their ability to form biofilms and also treatment-resistant microorganisms strains appear in the process of continuous sanitary treatment. The aim of the paper was to study the biofilms Enterococcus faecalis formation on the stainless steel AISI 321 depending on their initial quantity and surface roughness. The plates made of the stainless steel AISI 321of surface roughness Rа = 0.955 mkm, Rа = 0.63 mkm and Rа = 0.16 mkm were used for the investigation. It  was found that during 9 hours Enterococcus faecalis was forming the biofilms of weak density less than 0,5 units on the stainless steel surface of AISI 321 of roughness Rа = 0.955 mkm. After the 12th hour the intensive film formation process was noticed in the options with initial number of cells E.f from 2000 to 10 000 and 20–50 thousand/ cm2, the biofilm was getting of high density – 1.246 and 1.415 respectively with initial number of cells less than 1000 per 1 cm2 of steel surface and it was of medium density – 0.672 cells. The process of film formation on the steel surface of roughness 0.63 mkm was rather decelerating, in comparison with the surface of roughness 0.955 mkm. Though, despite this, in the options with initial number of E.f. cells from 2000 to 10 000 and 20–50 thousand/cm2 the biofilms were of high density after the 12th hour of incubation, i.e. it was the same as for the  surface of 0.955 mkm roughness.  The process of film formation at such initial numbers of E.f. on the surface of roughness 0.63 mkm was finishing after the 24th hour while at roughness 0.955 mkm – after the 18th hour of incubation. It was found that on the steel surface of roughness 0.16 mkm the process of film formation was greatly getting slower comparing to the surfaces of roughness 0.955 and 0.63 mkm. During 12 hours of E.f. incubation in case when the initial number of E.f. was less than 1000 per 1 cm2 the film was of weak density but in cases when the initial number was 2000 – 10 000 and 20–50 thousand/cm2 the biofilms were of medium and high density – 0.917 and 1.025 units. After 18 hours of incubation the film was of medium density only in case when the initial number was less than 1000 E.f. per 1 cm2 of the surface. At larger initial number of bacteria it was of high density. Only after 24 hours of E.f. incubation biofilms in all options were of high density. Thus, we came to the conclusion that E.f. biofilms formation on the stainless steel AISI 321 is influenced by the surface roughness and initial number of bacteria. The results have shown that on the plates of roughness 0,16 mkm the film formation process is slower than on the surface of roughness 0.955 and 0.63 mkm.

scholarly journals Disinfectant action of Cymbopogon sp. essential oils in different phases of biofilm formation by Listeria monocytogenes on stainless steel surface

Food Control ◽  
2010 ◽  
Vol 21 (4) ◽  
pp. 549-553 ◽  
Author(s):  
Maíra Maciel Mattos de Oliveira ◽  
Danilo Florisvaldo Brugnera ◽  
Maria das Graças Cardoso ◽  
Eduardo Alves ◽  
Roberta Hilsdorf Piccoli
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Essential Oils ◽  
Biofilm Formation ◽  
Steel Surface ◽  
Stainless Steel Surface

scholarly journals Pengaruh Parameter Shot Terhadap Kekerasan dan Kekasaran Permukaan Melalui Proses Shot-Peening Stainless Steel Tipe 316

2021 ◽  
Vol 19 (1) ◽  
pp. 18
Author(s):  
M I Mukhsen ◽  
R Nur ◽  
C. R. Rakka ◽  
M. A. Fattah
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Shot Peening ◽  
Steel Surface ◽  
Stainless Steel Surface ◽  
Bone Implant ◽  
316 Stainless Steel ◽  
Steel Shot ◽  
Implant Material

Type 316 stainless steel is a material that is often used in the medical world, especially as a material for making bone implant plates. However, the use of stainless steel as an implant material, stainless steel must be treated to increase the hardness and adjust the level of roughness on the surface. In this study, shot peening was carried out on the 316 stainless steel surface. The shooting parameters used were 2, 4, 6 minutes for the shooting duration, and 0o, 15o, 30o, 45o for the shooting angle, as well as the diameter of the steel shot used, i.e. 0.6 mm and 1 mm. The results of this study indicated that there was a change in the characteristic properties of 316 stainless steel, namely the hardness and surface roughness.

Wear-Resisting Property of 304 Stainless Steel Surface after Infiltration of Indium and Copper Alloys by Double Glow Technology

2014 ◽  
Vol 1030-1032 ◽  
pp. 263-267
Author(s):  
Yi Guang Wang ◽  
Jin Yong Xu ◽  
Bo Gao ◽  
Cheng Gao ◽  
Yin Wang
Keyword(s):  
Stainless Steel ◽  
Diffusion Layer ◽  
High Speed ◽  
Steel Surface ◽  
Copper Alloys ◽  
Testing Machine ◽  
Wear Testing ◽  
304 Stainless Steel ◽  
Stainless Steel Surface ◽  
Obvious Effect

Copper and Indium alloys elements were metallized into 304 Stainless Steel surface by Double Glow Plasma Surface Alloying Technology (Double Glow Technology for short). Microstructure and Resistance property of diffusion layer analyzer was analysed by metallographic microscope, scanning electron microscopy, energy spectrum, friction and wear testing machine of high speed reciprocating. The results show that process parameters of the permeability copper and indium has an obvious effect for the organization structure and performance of diffusion layer. The friction coefficient of alloying layer has a significant decrease compared with the substrate. The wear-resisting performance has an effective change.

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