Use of Nanotechnology to Mitigate Biofouling in Stainless Steel Devices Used in Food Processing, Healthcare, and Marine Environments

In humid environments, the formation of biofilms and microfouling are known to be the detrimental processes that first occur on stainless steel surfaces. This is known as biofouling. Subsequently, the conditions created by metabolites and the activity of organisms trigger corrosion of the metal and accelerate corrosion locally, causing a deterioration in, and alterations to, the performance of devices made of stainless steel. The microorganisms which thus affect stainless steel are mainly algae and bacteria. Within the macroorganisms that then damage the steel, mollusks and crustaceans are the most commonly observed. The aim of this review was to identify the mechanisms involved in biofouling on stainless steel and to evaluate the research done on preventing or mitigating this problem using nanotechnology in humid environments in three areas of human activity: food manufacturing, the implantation of medical devices, and infrastructure in marine settings. Of these protective processes that modify the steel surfaces, three approaches were examined: the use of inorganic nanoparticles; the use of polymeric coatings; and, finally, the generation of nanotextures.

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EFFECT OF SOLUTE CONCENTRATION AND PRE-SOIL INTERACTION ON THE MICROFLORA OF DAIRY ORIGIN ON STAINLESS STEEL SURFACES1

Journal of Milk and Food Technology ◽

10.4315/0022-2747-33.12.541 ◽

1970 ◽

Vol 33 (12) ◽

pp. 541-544 ◽

Cited By ~ 2

Author(s):

H. M. Barnhart ◽

R. B. Maxcy ◽

C. E. Georgi

Keyword(s):

Stainless Steel ◽

Water Loss ◽

Food Processing ◽

Solute Concentration ◽

Moisture Loss ◽

Stainless Steel Surface ◽

Dairy Food ◽

Temperature And Humidity ◽

Closed Systems ◽

Steel Surfaces

Use of modern dairy food processing equipment creates a complex microenvironment. Closed systems reduce air drying. The rate and extent of drying are dependent on temperature and humidity of the environment. These factors were studied to determine their impact on the microflora of films of milk on stainless steel surfaces. An ecosystem was established to simulate dairy food equipment by using 1cm2 pieces of stainless steel in controlled humidity chambers. Presoiling water loss from a film of milk, and solute concentration were studied to determine their influence on the fate of the microflora. Temperature and humidity of the atmosphere influenced the rate of moisture loss from films. Pre-soiling reduced the rate of water loss from films of milk sufficiently to allow bacterial growth at 12–80% relative humidity (RH). Results indicate bacteria can grow in a film placed in humidities well below the 95% RH limit previously projected. Apparently the substrate is influenced by interaction of the milk film and the stainless steel surface.

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

Applied and Environmental Microbiology ◽

10.1128/aem.01359-09 ◽

2009 ◽

Vol 75 (22) ◽

pp. 7182-7188 ◽

Cited By ~ 40

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 20ï¿½C) 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 5ï¿½C for 20 days. The suspended cells in all three products in which SS coupons were immersed were also used to inoculate freshly pasteurized milk (5ï¿½C 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 20ï¿½C). The opposite was observed when custard incubated at 20ï¿½C 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 5ï¿½C) in inoculated yogurt, marked detachment and growth were observed when these coupons were subsequently transferred and incubated at 5ï¿½C 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.

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

Journal of Food Protection ◽

10.4315/0362-028x-64.9.1369 ◽

2001 ◽

Vol 64 (9) ◽

pp. 1369-1376 ◽

Cited By ~ 82

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.

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

Journal of Food Protection ◽

10.4315/0362-028x-63.9.1204 ◽

2000 ◽

Vol 63 (9) ◽

pp. 1204-1207 ◽

Cited By ~ 172

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.

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Adhesion and biofilm formation by Staphylococcus aureus from food processing plants as affected by growth medium, surface type and incubation temperature

Brazilian Journal of Pharmaceutical Sciences ◽

10.1590/s1984-82502012000400018 ◽

2012 ◽

Vol 48 (4) ◽

pp. 737-745

Author(s):

Heloísa Maria Ângelo Jerônimo ◽

Rita de Cássia Ramos do Egypto Queiroga ◽

Ana Caroliny Vieira da Costa ◽

Isabella de Medeiros Barbosa ◽

Maria Lúcia da Conceição ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Stainless Steel ◽

Sodium Hypochlorite ◽

Peracetic Acid ◽

Food Processing ◽

Biofilm Formation ◽

Incubation Temperature ◽

Growth Media ◽

Processing Plants ◽

Steel Surfaces

This study assessed the effect of different growth media [BHI broth, BHI broth plus glucose (10 g/100 mL) and BHI broth plus NaCl (5 g/100 mL)] and incubation temperatures (28 or 37 ºC) on the adherence, detachment and biofilm formation on polypropylene and stainless steel surfaces (2 x 2 cm coupons) for a prolonged period (24-72 h) by some strains of Staphylococcus aureus (S3, S28 and S54) from food processing plants. The efficacy of the sanitizers sodium hypochlorite (250 mg/mL) and peracetic acid (30 mg/mL) in reducing the number of viable bacterial cells in a preformed biofilm was also evaluated. S. aureus strains adhered in highest numbers in BHI broth, regardless of the type of surface or incubation temperature. Cell detachment from surfaces revealed high persistence over the incubation period. The number of cells needed for biofilm formation was noted in all experimental systems after 3 days. Peracetic acid and sodium hypochlorite were not efficient in completely removing the cells of S. aureus adhered onto polypropylene and stainless steel surfaces. From these results, the assayed strains revealed high capacities to adhere and form biofilms on polypropylene and stainless steel surfaces under the different growth conditions, and the cells in biofilm matrixes were resistant to total removal when exposed to the sanitizers sodium hypochlorite and peracetic acid.

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