A model heat-exchange apparatus for the investigation of fouling of stainless steel surfaces by milk I. Deposit formation at 100 °C

1989 ◽  
Vol 56 (2) ◽  
pp. 201-209 ◽  
Author(s):  
Carole L. Foster ◽  
Michel Britten ◽  
Margaret L. Green
Keyword(s):  
Stainless Steel ◽  
Heat Exchange ◽  
Time Course ◽  
Small Scale ◽  
Lag Phase ◽  
Stainless Steel Surface ◽  
Deposit Formation ◽  
Factors Affecting ◽  
Steel Surfaces ◽  
Exchange Apparatus

SummaryA model heat-exchange apparatus was used to investigate the factors affecting deposit formation from milk on a stainless steel surface at 100 °C. The structure and composition of the deposits were determined by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and chemical analysis after solution in alkali. The effects of changing the pH, preheating and skimming of the milk were similar to those observed in a small-scale continuous ultra high temperature plant. The time course of deposit formation showed that a lag phase did not occur, but the deposit which formed after more than 45 min was more porous than that formed after shorter times. Most (50–90%) of the fresh deposit was readily removed by sonication, leaving a sublayer richer in minerais than the original. The results provide evidence for the two-layer model for deposit formation proposed by Tissier & Lalande (1986).

Destruction of Alicyclobacillus acidoterrestris Spores in Apple Juice on Stainless Steel Surfaces by Chemical Disinfectants

2009 ◽  
Vol 72 (3) ◽  
pp. 510-514 ◽  
Author(s):  
RICHARD PODOLAK ◽  
PHILIP H. ELLIOTT ◽  
BRADLEY J. TAYLOR ◽  
AAKASH KHURANA ◽  
DARRYL G. BLACK
Keyword(s):  
Stainless Steel ◽  
Chlorine Dioxide ◽  
Apple Juice ◽  
Octanoic Acid ◽  
Stainless Steel Surface ◽  
Peroxyacetic Acid ◽  
Alicyclobacillus Acidoterrestris ◽  
Practical Applications ◽  
Maximum Reduction ◽  
Steel Surfaces

A study was conducted to determine the effects of three commercially available disinfectants on the reduction of Alicyclobacillus acidoterrestris spores in single-strength apple juice applied to stainless steel surfaces. Apple juice was inoculated with A. acidoterrestris spores, spread onto the surface of stainless steel chips (SSC), dried to obtain spore concentrations of approximately 104 CFU/cm2, and treated with disinfectants at temperatures ranging from 40 to 90°C. The concentrations of disinfectants were 200, 500, 1,000, and 2,000 ppm of total chlorine for Clorox (CL) (sodium hypochlorite); 50, 100, and 200 ppm of total chlorine for Carnebon 200 (stabilized chlorine dioxide); and 1,500, 2,000, and 2,600 ppm for Vortexx (VOR) (hydrogen peroxide, peroxyacetic acid, and octanoic acid). For all temperatures tested, VOR at 2,600 ppm (90°C) and CL at 2,000 ppm (90°C) were the most inhibitory against A. acidoterrestris spores, resulting in 2.55- and 2.32-log CFU/cm2 reductions, respectively, after 2 min. All disinfectants and conditions tested resulted in the inactivation of A. acidoterrestris spores, with a maximum reduction of >2 log CFU/cm2. Results from this study indicate that A. acidoterrestris spores, in single-strength apple juice, may be effectively reduced on stainless steel surface by VOR and CL, which may have practical applications in the juice industry.

Preliminary stages of fouling from whey protein solutions

1993 ◽  
Vol 60 (4) ◽  
pp. 467-483 ◽  
Author(s):  
M. Teresa Belmar-Beiny ◽  
Peter J. Fryer
Keyword(s):  
Stainless Steel ◽  
Turbulent Flows ◽  
Photoelectron Spectroscopy ◽  
Test Fluid ◽  
Protein Solutions ◽  
Lag Phase ◽  
Stainless Steel Surface ◽  
Fluid Temperature ◽  
X Ray ◽  
Sequence Of Events

SummaryFouling from milk fluids is a severe industrial problem which reduces the efficiency of process plant. The chemistry of fouling has been thoroughly investigated but the sequence of events that occur is not yet clear. Deposit contains both protein and minerals. Experiments have been carried out to determine the sequence of events in the fouling of stainless steel surfaces at 96 °C from turbulent flows of whey. Contact times between 4 and 210 s have been studied, and surface analysis techniques used to detect the distribution of elements. The first layer of deposit, formed after 4 s of contact between the fluid and the surface (fluid temperature 68 and 73 °C), consisted mainly of protein and was identified by X-ray photoelectron spectroscopy analysis. There was a lag phase of up to 150 s for a fluid temperature of 73 °C before deposit aggregates were observed to adsorb on to the surface. These aggregates were identified as protein and Ca by X-ray elemental mapping. No P was found in any experiments for this exposure. After 60 min contact time, however, both Ca and P were found at the interface between deposit and the stainless steel surface, irrespective of the Ca and P content of the test fluid.

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

1970 ◽  
Vol 33 (12) ◽  
pp. 541-544 ◽  
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.

Scanning Electron Microscopic Examination of Yersinia enterocolitica Attached to Stainless Steel at Selected Temperatures and pH values1

1988 ◽  
Vol 51 (6) ◽  
pp. 445-448 ◽  
Author(s):  
PAULA J. HERALD ◽  
EDMUND A. ZOTTOLA
Keyword(s):  
Stainless Steel ◽  
Yersinia Enterocolitica ◽  
Steel Surface ◽  
Electron Microscopic Examination ◽  
Growth Conditions ◽  
Stainless Steel Surface ◽  
Electron Microscopic ◽  
Scanning Electron Microscopic ◽  
Steel Surfaces ◽  
Scanning Electron

Attachment of Yersinia enterocolitica to stainless steel surfaces at 35, 21, and 10°C was investigated using scanning electron microscopy (SEM). Cells adhered at all three temperatures, but, in general, the greatest number of adhered cells were observed at pH 8 and 21°C. Multi-flagellated cells were noted under these growth conditions. When grown at pH 9.5 and 21°C, fibrils were observed between cells and extending to the stainless steel surface. Fewer cells with flagella were seen at this pH. Adherence may be related to the flagella and any exopolymer surrounding the cells.

Comparison of Nucleation Site Density for Pool Boiling and Gas Nucleation

2005 ◽  
Vol 128 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Yusen Qi ◽  
James F. Klausner
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Pool Boiling ◽  
Nucleation Site ◽  
Stainless Steel Surface ◽  
Distilled Water ◽  
Site Density ◽  
Significant Difference ◽  
Steel Surfaces ◽  
Nucleation Site Density

It has been well established that the rate of heat transfer associated with boiling systems is strongly dependent on the nucleation site density. Over many years attempts have been made to predict nucleation site density in boiling systems using a variety of techniques. With the exception of specially prepared surfaces, these attempts have met with little success. This paper presents an experimental investigation of nucleation site density measured on roughly polished brass and stainless steel surfaces for gas nucleation and pool boiling over a large parameter space. A statistical model used to predict the nucleation site density in saturated pool boiling is also investigated. The fluids used for this study, distilled water and ethanol, are moderately wetting and highly wetting, respectively. Using distilled water it has been observed that the trends of nucleation site density versus the inverse of the critical radius are similar for pool boiling and gas nucleation. The nucleation site density is higher for gas nucleation than for pool boiling. An unexpected result has been observed with ethanol as the heat transfer fluid, which casts doubt on the general assumption that heterogeneous nucleation in boiling systems is exclusively seeded by vapor trapping cavities. Due to flooding, few sites are active on the brass surface and at most two are active on the stainless steel surface during gas nucleation experiments. However, nucleation sites readily form in large concentration on both the brass and stainless steel surfaces during pool boiling. The pool boiling nucleation site densities for ethanol on rough and mirror polished brass surfaces are also compared. It shows that there is not a significant difference between the measured nucleation site densities on the smooth and rough surfaces. These results suggest that, in addition to vapor trapping cavities, another mechanism must exist to seed vapor bubble growth in boiling systems.

Improved Quantitative Recovery of Listeria monocytogenes from Stainless Steel Surfaces Using a One-Ply Composite Tissue

2004 ◽  
Vol 67 (10) ◽  
pp. 2212-2217 ◽  
Author(s):  
KEITH L. VORST ◽  
EWEN C. D. TODD ◽  
ELLIOT T. RYSER
Keyword(s):  
Stainless Steel ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Steel Plates ◽  
Stainless Steel Surface ◽  
Disc Diffusion ◽  
Buffer Solution ◽  
Composite Tissue ◽  
Steel Surfaces ◽  
Diffusion Assay

Four sampling devices, a sterile environmental sponge (ES), a sterile cotton-tipped swab (CS), a sterile calcium alginate fiber-tipped swab (CAS), and a one-ply composite tissue (CT), were evaluated for quantitative recovery of Listeria monocytogenes from a food-grade stainless steel surface. Sterile 304-grade stainless steel plates (6 by 6 cm) were inoculated with approximately 106 CFU/cm2 L. monocytogenes strain Scott A and dried for 1 h. The ES and CT sampling devices were rehydrated in phosphate buffer solution. After plate swabbing, ES and CT were placed in 40 ml of phosphate buffer solution, stomached for 1 min and hand massaged for 30 s. Each CS and CAS device was rehydrated in 0.1% peptone before swabbing. After swabbing, CS and CAS were vortexed in 0.1% peptone for 1 min. Samples were spiral plated on modified Oxford agar with modified Oxford agar Rodac Contact plates used to recover any remaining cells from the stainless steel surface. Potential inhibition from CT was examined in both phosphate buffer solution and in a modified disc-diffusion assay. Recovery was 2.70, 1.34, and 0.62 log greater using CT compared with ES, CS, and CAS, respectively, with these differences statistically significant (P < 0.001) for ES and CT and for CAS, CS, and CT (P < 0.05). Rodac plates were typically overgrown following ES, positive after CS and CAS, and negative after CT sampling. CT was noninhibitory in both phosphate buffer solution and the modified disc-diffusion assay. Using scanning electron microscopy, Listeria cells were observed on stainless steel plates sampled with each sampling device except CT. The CT device, which is inexpensive and easy to use, represents a major improvement over other methods in quantifying L. monocytogenes on stainless steel surfaces and is likely applicable to enrichment of environmental samples.

A model heat exchange apparatus for the investigation of fouling of stainless steel surfaces by milk II. Deposition of fouling material at 140 °C, its adhesion and depth profiling

1990 ◽  
Vol 57 (3) ◽  
pp. 339-348 ◽  
Author(s):  
Carole L. Foster ◽  
Margaret L. Green
Keyword(s):  
Stainless Steel ◽  
Steel Surface ◽  
Secondary Ion Mass Spectrometry ◽  
Depth Profiling ◽  
Heating Time ◽  
Stainless Steel Surface ◽  
Heating Section ◽  
Fat Removal ◽  
Secondary Ion ◽  
Exchange Apparatus

SummaryFormation and adhesion of fouling deposit during heating of milk at a stainless steel surface were studied separately using a model apparatus. The amount of deposit and proportion of minerals present increased with increase in surface temperature. At 140 °C, the amount of deposit formed increased linearly with heating time, becoming more uneven in appearance. The variations of deposit formation at 140 °C with pH of the milk, with fat removal and with preheating were similar to those observed in the final heating section of continuous UHT plants. Deposits containing a higher proportion of protein were easier to remove. The remaining inner layer had a smoother appearance and contained a higher proportion of minerals than the original deposit. Depth profiling, using secondary ion mass spectrometry, showed that protein was concentrated on the outside of deposits with calcium phosphate being concentrated closest to the steel surface.

scholarly journals Factors Affecting Adhesion of Staphylococcus epidermidis to Stainless Steel Surface

2008 ◽  
Vol 9 (4) ◽  
pp. 251-259 ◽  
Author(s):  
Melba Padua ORTEGA ◽  
Tomoaki HAGIWARA ◽  
Hisahiko WATANABE ◽  
Takaharu SAKIYAMA
Keyword(s):  
Stainless Steel ◽  
Staphylococcus Epidermidis ◽  
Steel Surface ◽  
Stainless Steel Surface ◽  
Factors Affecting

The influence of chemical cleaning methods on pitting morphology attributed to microbially influenced corrosion of stainless steels

CORROSION ◽  
10.5006/3707 ◽  
2020 ◽  
Author(s):  
Muhammad Awais Javed ◽  
Nathaniel Rieders ◽  
Iwona Beech ◽  
Recep Avci ◽  
Wayne Neil ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Stainless Steel Surface ◽  
Metallic Materials ◽  
Chemical Cleaning ◽  
Microbially Influenced Corrosion ◽  
Quantitative Measurements ◽  
Treatment Type ◽  
Steel Surfaces ◽  
Potential Impact ◽  
Cleaning Methods

Chemical cleaning methods are frequently employed for the removal of biofilm/corrosion products from metallic materials to evaluate the type and severity of microbially influenced corrosion (MIC) damage. The study described here investigates the effect of commonly applied cleaning treatments on the dissolution of stainless steel surface inclusions and emphasizes the potential impact of such treatments on MIC diagnostics. Polished 304 grade stainless steel coupons were ultrasonicated for 1, 3 and 7 min in each of the three commonly applied agents, i.e. Clarke’s, nitric acid and hydrofluoric acid-based solutions. Post-treatment analyses of steel surfaces revealed pitting attack. For each treatment type and duration, the morphology and quantitative measurements of pits were recorded. Shape, size and depth of examined pits closely resembled damage that, in many laboratory-based studies, have been attributed to MIC. The investigation herein demonstrates that caution ought to be exerted when implicating MIC as the cause of stainless steel pitting damage.

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