Conveyor Belt Materials Research Articles

Microbial investigation of cleanability of different plastic and metal surfaces used by the food industry

Different conveyor belt materials used by the meat and other food industries were compared, regarding their cleanability as bacterial reduction rates in relation to their surface topography. Eleven thermoplastic polymers, four stainless steels, and five aluminized nanostructured surfaces were investigated under laboratory conditions. Cleanings were conducted with water only, and with an alkaline foam detergent. Overall, scanning electron microscopy revealed remarkable differences in the surface topography of the tested surfaces. Water cleaning results showed that nanostructured aluminized surfaces achieved significantly higher cleanability rates compared to the eight thermoplastic surfaces, as well as the glass-bead blasted rough stainless steel. Thermoplastic surfaces showed overall low cleanability rates when cleaned with alkaline detergent, while stainless steel and nanoporous aluminum showed high variations. Overall, nanoporous aluminum showed promising results as it can be used to coat conveyor belts. However, compatibility with cleaning detergent and sensitivity to scratches must be further investigated. Overall, it can be concluded that cleanability is not only influenced by surface roughness, but also by the overall surface finish, scratches, and defects.

Cold atmospheric pressure plasma for the sanitation of conveyor belt materials: Decontamination efficacy against adherent bacteria and biofilms of Escherichia coli and effect on surface properties

The inactivation efficacy of a cold atmospheric pressure plasma jet against Escherichia coli DH5α adherent cells and biofilms on two conveyor belt materials was evaluated. A 120 s treatment time with a 3 cm treatment distance from the surface reduced both adherent cells (initial 5.6 ± 0.2 log CFU/coupon) and 24 h biofilms (initial 5.8 ± 0.4 log CFU/coupon) on stainless steel (SS) by >4.6 log CFU. While the same treatment reduced adherent cells (initial 5.7 ± 0.5 log CFU/coupon) and 24 h biofilms (initial 6.9 ± 0.5 log CFU/coupon) on polyvinyl chloride (PVC) by 3.8 ± 0.9 and 3.5 ± 0.5 log CFU, respectively. Mature biofilms (72 h grown) were more resistant than 24 h grown biofilms. Lower microbial reductions were observed on scratched surfaces compared to intact ones. No changes were observed in SS and PVC surfaces in terms of chemical properties and visual topography. CAPP is a promising waterless technique for the sanitation of metallic and polymeric conveyor belt surfaces. Industry relevanceCold atmospheric pressure plasma (CAPP) has the potential as waterless technology to inactivate bacteria and their biofilms on food contact surfaces without affecting the material properties and the visual topography. CAPP can be integrated for industrial operation by mounting a CAPP jet on a robotic arm or moving a conveyor belt under a stationary CAPP jet for surface sanitation. This environmental-friendly and residue-free nature technology can be useful in the food industry.

Perancangan Conveyor Pada Mesin Pengisi Botol Otomatis

Technology continues to develop from time to time with all the innovations that aim to ease all human affairs, from the industrial world aspect. Human needs are increasing, developing and varying, to meet the needs of the industry requires a tool that can control and control the machining process automatically so as to simplify and save human labor, such as designing an automatic conveyor on an automatic bottle filling machine using a PLC (Programmable Logic Controller). With a PU (polyurethane) conveyor belt material that is rough, slippery and elastic, the surface of the belt conveyor works horizontally and can carry bottles at a conveyor speed that uses a 12v DC power window motor, a speed of 90 rpm and a torque of 3N.m without a load. The speed of the conveyor with a bottle distance of 1mm and has a time of 6.82 s, then the result of a one-way bottle speed is 0.146 m/s.

Using the asymptotic approximation of the Maxwell element model for the analysis of stress in a conveyor belt

The features of the propagation of dynamic stresses in a conveyor belt, the material properties of which correspond to the Maxwell element model, are considered. Analytical expressions are presented for calculating the dynamic elastic modulus, the loss modulus, and the angle of mechanical loss depending on the frequency of longitudinal oscillations in the belt of an extended transport conveyor. To analyze the dynamic stress propagation process, dimensionless parameters are introduced that characterize the specific features of the viscoelastic process in a conveyor belt, the material properties of which correspond to the Maxwell element model. The transition to the dimensionless Maxwell element model is made and the analysis of the relationship between stress and deformation of a conveyor belt element for extremely large and small values of dimensionless parameters is made. The substantiation of the scope of the Maxwell element model is given. It is shown that at sufficiently high frequencies of longitudinal stress oscillations in a conveyor belt, at which the oscillation period is much less than the characteristic oscillation decay time, the relationship between stress and deformation of the conveyor belt element corresponds to Hooke's law. A qualitative analysis of the relaxation time was carried out for a conveyor belt material, the properties of which correspond to the Maxwell element model. The analysis of the propagation of dynamic stresses in the conveyor belt for the characteristic operating modes of the transport conveyor is carried out. The conveyor operating mode with a constant deformation rate of the belt element; the mode in which a constant load is suddenly applied to the belt element; the conveyor operating mode with an instantly applied load to the belt element were investigated. It was determined that in cases where the characteristic process time significantly exceeds the stress relaxation time in the conveyor belt or the longitudinal oscillation period is much less than the stress relaxation time in the conveyor belt, the Maxwell element model can be replaced with a sufficient degree of accuracy by the Hooke element model.

Pulsed Ultraviolet Light Decontamination of Meat Conveyor Surfaces.

Contact with continuous belt conveyors during processing results in opportunities for pathogenic and spoilage microorganisms to contaminate meat products. The objective of this project is to investigate the germicidal response on the surface of food-grade conveyor belt materials treated with pulsed ultraviolet (PUV) light. Four conveyor belt types including: a stainless-steel chain-link belt, a polytetrafluoroethylene (PTFE)-coated fabric belt, a solid pliable polymer belt, and a rigid-linked polymer belt, were evaluated for the inactivation of Escherichia coli K12-NSR strain and lactic acid bacteria (LAB). Prior to bacterial inoculation, samples were classified as soiled or unsoiled, based on the presence or absence of pork intramuscular fluid on the surfaces of the conveyor samples. Using a variable speed conveyor, equipped with a Xenon flashlamp positioned 10-cm above the surface, each belt sample was exposed to PUV light at three fixed conveyor speeds: 3.05, 15.24, and 30.48 cm/sec, resulting in a total energy exposure of 3.31, 0.66 and 0.33 J/cm2, respectively. For samples inoculated with E. coli K12-NSR, the surface condition (soiled or unsoiled) by treatment interaction was significant for microbial inactivation on the surface of the rigid polymer linked belt (P < 0.05). For samples inoculated with the LAB cocktail, the same interaction was significant for the PTFE-coated fabric belt and the solid pliable polymer belt (P < 0.05). Microbial reduction ranged from 0.74 to 5.04 log10 CFU/cm2 for E. coli K12-NSR and 0.63 to 4.61 Log10 CFU/cm2 for LAB for the evaluated treatment parameters. The results of this project demonstrate that PUV light is an effective means of decontamination for conveyor belts during food processing.

Selection of the conveyor belt material for edible film production by a continuous casting process

Abstract The scaling up of the wet process and the design of a coating line to produce edible films, require the consideration of several factors such as, the film formulation, drying kinetics of the films, and the selection of a suitable support material in which to pour the solution. This work aimed to select the most suitable material for the construction of a conveyor belt for the fabrication of edible films through the wet process. The surface properties of the starch film-forming solution were determined. Several commercial materials for conveyor belts were tested. The film-forming solution spreadability and work of adhesion were determined. The mechanical behavior of the dry film was evaluated through mechanical properties and peeling resistance. All materials tested showed good performance under the operational conditions assayed to obtain edible films. Finally, the polyurethane band was chosen due to its appropriate performance and lower cost.

Listeria Monocytogenes Biofilm Removal Using Different Commercial Cleaning Agents.

Effective cleaning and disinfection (C&D) is pivotal for the control of Listeria monocytogenes in food processing environments. Bacteria in biofilms are protected from biocidal action, and effective strategies for the prevention and removal of biofilms are needed. In this study, different C&D biofilm control strategies on pre-formed L. monocytogenes biofilms on a conveyor belt material were evaluated and compared to the effect of a conventional chlorinated, alkaline cleaner (agent A). Bacterial reductions up to 1.8 log were obtained in biofilms exposed to daily C&D cycles with normal user concentrations of alkaline, acidic, or enzymatic cleaning agents, followed by disinfection using peracetic acid. No significant differences in bactericidal effects between the treatments were observed. Seven-day-old biofilms were more tolerant to C&D than four-day-old biofilms. Attempts to optimize biofilm eradication protocols for four alkaline, two acidic, and one enzymatic cleaning agent, in accordance with the manufacturers’ recommendations, were evaluated. Increased concentrations, the number of subsequent treatments, the exposure times, and the temperatures of the C&D agents provided between 4.0 and >5.5 log reductions in colony forming units (CFU) for seven-day-old L. monocytogenes biofilms. Enhanced protocols of conventional and enzymatic C&D protocols have the potential for improved biofilm control, although further optimizations and evaluations are needed.

Whole room disinfection with hydrogen peroxide mist to control Listeria monocytogenes in food industry related environments

Listeria monocytogenes surviving daily cleaning and disinfection is a challenge for many types of food industries. In this study, it was tested whether whole room disinfection (WRD) with H2O2 mist could kill L. monocytogenes under conditions relevant for the food industry. Survival of a mixture of four L. monocytogenes strains exposed to H2O2 mist was investigated in a 36 m3 room. A commercial machine produced H2O2 mist by pumping a 5% H2O2 solution containing 0.005% silver through a nozzle, and breaking the liquid up in droplets using pressurized air.When a suspension of bacteria in 0.9% NaCl applied on stainless steel coupons was exposed to WRD with H2O2 mist, a >5 log reduction (LR) of L. monocytogenes was observed. Similar reductions were observed in all tests with conditions between 12 and 20 °C, H2O2 concentrations of 35–80 ppm and 1–2 h exposure. It was shown that the H2O2 in the mist dissolved and accumulated in the liquid on the steel, and acted against L. monocytogenes in the liquid phase. At high cell concentrations, the effect was reduced if cells were pregrown at highly aerated conditions. The anti-listerial effect was robust against protein and fat, but the effect was quenched by raw meat and raw salmon, probably due to high catalase activity. The effect of whole room disinfection with H2O2 against dried L. monocytogenes cells was 1–2 LR, however the effect of air-drying by itself lead to 3–4 LR. When biofilms were exposed to WRD, no surviving L. monocytogenes were observed on stainless steel, however for L. monocytogenes on a PVC conveyor belt material, there were surviving bacteria, with about 2 LR. Screening of 54 L. monocytogenes strains for growth susceptibility to H2O2 showed that their sensitivity to H2O2 was very similar, thus WRD with H2O2 are likely to be robust against strain variation in susceptibility to H2O2. Production of H2O2 mist resulted in increased room humidity, and this may limit the maximum H2O2 concentration achievable, especially at low temperatures. The results in this study show that whole room disinfection with H2O2 may have potential to control L. monocytogenes in the food industry, however intervention studies in the food industry are needed to verify the effect in practical use.

Classification of impact damage on a rubber-textile conveyor belt using Naïve-Bayes methodology

The selection of the proper materials is an integral component of most technological processes, and the selection of durable conveyor belt materials is a principal example. The overall quality of a conveyor belt and its service life under impact loads are very important factors. Accordingly, the purpose of the present work is to classify the types of impact damage that occur in rubber-textile conveyor belts. Under laboratory conditions, different types of conveyor belts (unused, used, used with a subsequent top cover layer renovation) were tested. They were subjected to variables such as the drop height and the type of impacting material. The severity of the conveyor belt damage was categorised using four degrees. An examination of the effects of the selected factors on the degree of damage was carried out using probability theory. In particular, an evaluation of the experimental test data and predictive modelling was conducted using the Naïve Bayes Classifier.

Listeria monocytogenes persistence and transfer to cantaloupes in the packing environment is affected by surface type and cleanliness

Investigation of the 2011 U.S. listeriosis outbreak associated with consumption of contaminated cantaloupes (Cucumis melo L) revealed that transfer of Listeria monocytogenes from equipment surfaces to melons in the packing facility was a potential route of contamination. The study presented here examined L. monocytogenes attachment and persistence on soiled materials and different types of equipment surfaces, and transfer to melons in a simulated-packing environment. Attachment involved the exposure of roller conveyors (polyvinyl chloride), conveyor belts (polyvinyl chloride, polyurethane, and nitrile rubber), and brush filaments (nylon and polyethylene) to ca. 7 log10 CFU/mL of a L. monocytogenes multi-strain inoculum for 10 and 60 min. L. monocytogenes showed similar (p > 0.05) attachment to all types of surfaces, and populations attached to surfaces following exposure for 10 min were not significantly different (p > 0.05) from that attached to surfaces after 60 min. Clean and soiled surfaces of nylon-brush filaments, conveyor belts, and foam pads were each inoculated with a L. monocytogenes multi-strain mixture (4.5 log10 CFU/mL) and subsequently stored at 25 °C, and L. monocytogenes populations on the surfaces were recovered for up to 15 days. L. monocytogenes populations on clean surfaces decreased from 4.5 log10 CFU/surface on day 0 to the detection limit by day 14; L. monocytogenes was still present on clean surfaces following enrichment on day 21. However, L. monocytogenes populations remained unchanged on soiled surfaces from day 0–14. Multivariate ANOVA revealed that soiled surfaces significantly (p < 0.05) promoted L. monocytogenes persistence compared to clean surfaces. Comparison of clean surfaces revealed that foam pads and brushes significantly (p < 0.05) promoted L. monocytogenes persistence compared to conveyor belt materials. Conveyor belts and foam pads were spot-inoculated (2.5 log10 CFU/surface), and 15 consecutive wet melons were manually rolled over each spot (n = 6 replicates), and melons were tested for the presence/absence of L. monocytogenes. Foam pads were found to contaminate significantly (p < 0.05) more melons than conveyor belts (polyvinyl chloride, polyurethane, and nitrile rubber). Soiled surfaces supported the survival of higher populations of L. monocytogenes, and surface type affected L. monocytogenes contamination transferred to specific melons.

Sanitizing in Dry-Processing Environments Using Isopropyl Alcohol Quaternary Ammonium Formula

Dry-processing environments are particularly challenging to clean and sanitize because introduced water can favor growth and establishment of pathogenic microorganisms such as Salmonella. Our objective was to determine the efficacy of an isopropyl alcohol quaternary ammonium (IPAQuat) formula for eliminating potential Salmonella contamination on food contact surfaces. Clean stainless steel coupons and conveyor belt materials used in dry-processing environments were spot inoculated in the center of coupons (5 by 5 cm) with a six-serotype composite of Salmonella (approximately 10 log CFU/ml), subjected to IPAQuat sanitizer treatments with exposure times of 30 s, 1 min, or 5 min, and then swabbed for enumeration of posttreatment survivors. A subset of inoculated surfaces was soiled with a breadcrumb-flour blend and allowed to sit on the laboratory bench for a minimum of 16 h before sanitation. Pretreatment Salmonella populations (inoculated controls, 0 s treatment) were approximately 7.0 log CFU/25 cm(2), and posttreatment survivors were 1.31, 0.72, and < 0.7 (detection limit) log CFU/25 cm(2) after sanitizer exposure for 30 s, 1 min, or 5 min, respectively, for both clean (no added soil) and soiled surfaces. Treatment with the IPAQuat formula using 30-s sanitizer exposures resulted in 5.68-log reductions, whereas >6.0-log reductions were observed for sanitizer exposures of 1 and 5 min. Because water is not introduced into the processing environment with this approach, the IPAQuat formula could have sanitation applications in dry-processing environments to eliminate potential contamination from Salmonella on food contact surfaces.

Quantification of Optical and Physical Properties of Combustion-Generated Carbonaceous Aerosols (

A series of experiments were conducted to quantify and characterize the optical and physical properties of combustion-generated aerosols during both flaming and smoldering combustion of three materials common to underground mines-Pittsburgh Seam coal, Styrene Butadiene Rubber (a common mine conveyor belt material), and Douglas-fir wood-using a combination of analytical and gravimetric measurements. Laser photometers were utilized in the experiments for continuous measurement of aerosol mass concentrations and for comparison to measurements made using gravimetric filter samples. The aerosols of interest lie in the size range of tens to a few hundred nanometers, out of range of the standard photometer calibration. To correct for these uncertainties, the photometer mass concentrations were compared to gravimetric samples to determine if consistent correlations existed. The response of a calibrated and modified combination ionization/photoelectric smoke detector was also used. In addition, the responses of this sensor and a similar, prototype ionization/photoelectric sensor, along with discrete angular scattering, total scattering, and total extinction measurements, were used to define in real time the size, morphology, and radiative transfer properties of these differing aerosols that are generally in the form of fractal aggregates. SEM/TEM images were also obtained in order to compare qualitatively the real-time, continuous experimental measurements with the visual microscopic measurements. These data clearly show that significant differences exist between aerosols from flaming and from smoldering combustion and that these differences produce very different scattering and absorption signatures. The data also indicate that ionization/photoelectric sensors can be utilized to measure continuously and in real time aerosol properties over a broad spectrum of applications related to adverse environmental and health effects.

Cleaning of Conveyor Belt Materials Using Ultrasound in a Thin Layer of Water

Cleaning of conveyor belts in the food industry is imperative for preventing the buildup of microorganisms that can contaminate food. New technologies for decreasing water and energy consumption of cleaning systems are desired. Ultrasound can be used for cleaning a wide range of materials. Most commonly, baths containing fairly large amounts of water are used. One possibility to reduce water consumption is to use ultrasonic cavitation in a thin water film on a flat surface, like a conveyor belt. In order to test this possibility, a model system was set up, consisting of an ultrasound transducer/probe with a 70-mm-diameter flat bottom, operating at 19.8 kHz, and contaminated conveyor belt materials in the form of coupons covered with a thin layer of water or water with detergent. Ultrasound was then applied on the water surface at different power levels (from 46 to 260 W), exposure times (10 and 20 s), and distances (2 to 20 mm). The model was used to test two different belt materials with various contamination types, such as biofilms formed by bacteria in carbohydrate- or protein-fat-based soils, dried microorganisms (bacteria, yeasts, and mold spores), and allergens. Ultrasound treatment increased the reduction of bacteria and yeast by 1 to 2 log CFU under the most favorable conditions compared with water or water-detergent controls. The effect was dependent on the type of belt material, the power applied, the exposure time, and the distance between the probe and the belt coupon. Generally, dried microorganisms were more easily removed than biofilms. The effect on mold spores was variable and appeared to be species and material dependent. Spiked allergens were also efficiently removed by using ultrasound. The results in this study pave the way for new cleaning designs for flat conveyor belts, with possibilities for savings of water, detergent, and energy consumption.

Attachment ofSalmonella serovars andListeria monocytogenes to stainless steel and plastic conveyor belts

In poultry industry, cross-contamination due to processing equipment and contact surfaces is very common. This study examined the extent of bacterial attachment to 6 different types and design of conveyor belts: stainless steel-single loop, stainless steel-balance weave, polyurethane with mono-polyester fabric, acetal, polypropylene mesh top, and polypropylene. Clean conveyor belts were immersed separately in either a cocktail of Salmonella serovars (Salmonella Typhimurium and Salmonella Enteritidis) or Listeria monocytogenes strains (Scott A, Brie 1, ATCC 6744) for 1 h at room temperature. Soiled conveyor chips were dipped in poultry rinses contaminated with Salmonella or Listeria cocktail and incubated at 10°C for 48 h. The polyurethane with mono-polyester fabric conveyor belt and chip exhibited a higher (P<0.05) mean number of attached Salmonella serovars (clean: 1.6 to 3.6 cfu/cm2; soiled: 0.8 to 2.4 cfu/cm2) and L. monocytogenes (clean: 4.0 to 4.3 cfu/cm2; soiled: 0.3 to 2.1 cfu/cm2) in both clean and soiled conditions. The stainless steel conveyor belt attached a lower (P<0.05) number of Salmonella serovars (clean: 0 to 2.6 cfu/cm2; soiled: 0.4 to 1.3 cfu/cm2) and L. monocytogenes (clean: 0.4 to 2.9 cfu/cm2; soiled: 0 to 0.7 cfu/cm2) than the polymeric materials, indicating weaker adhesion properties. Plastic conveyor belts exhibited stronger bacterial adhesion compared with stainless steel. The result suggests the importance of selecting the design and finishes of conveyor belt materials that are most resistant to bacterial attachment.

Research on Web Press Printing without Ink Detector

Printing press manufacturers need to detect assembled machine whether the printing is qualified. This wastes a lot of paper, ink and human, and is not conducive to business efficiency. In this paper, through analysis of web press, the instrument is developed that takes the paper to detect the offset with non-printing ink on the printing press, through high-precision optical sensors, it can get the offset of conveyor belt material in the course of the amount of deviation. The amount of assembly precision machine is detected based on deviation; Then design a circuit tester hardware and software; Finally, the detector was tested, the results show that the detector is designed to achieve the design requirements.

Survival of Listeria monocytogenes on a conveyor belt material with or without antimicrobial additives

Survival of Listeria monocytogenes on a conveyor belt material with or without antimicrobial additives, in the absence or presence of food debris from meat, fish and vegetables and at temperatures of 10, 25 and 37 °C was investigated. The pathogen survived best at 10 °C, and better at 25 °C than at 37 °C on both conveyor belt materials. The reduction in the numbers of the pathogen on belt material with antimicrobial additives in the first 6 h at 10 °C was 0.6 log unit, which was significantly higher ( P < 0.05) than the reduction of 0.2 log unit on belt material without additives. Reductions were significantly less ( P < 0.05) in the presence of food residue. At 37 °C and 20% relative humidity, large decreases in the numbers of the pathogen on both conveyor belt materials during the first 6 h were observed. Under these conditions, there was no obvious effect of the antimicrobial substances. However, at 25 °C and 10 °C and high humidity (60–75% rh), a rapid decrease in bacterial numbers on the belt material with antimicrobial substances was observed. Apparently the reduction in numbers of L. monocytogenes on belt material with antimicrobial additives was greater than on belt material without additives only when the surfaces were wet. Moreover, the presence of food debris neutralized the effect of the antimicrobials. The results suggest that the antimicrobial additives in conveyor belt material could help to reduce numbers of microorganisms on belts at low temperatures when food residues are absent and belts are not rapidly dried.

Doping of Conveyor Belt Materials with Nanostructured Fillers to Adapt Innovative Performance Characteristics

Doping of Conveyor Belt Materials with Nanostructured Fillers to Adapt Innovative Performance Characteristics

Ultrasonic Cleaning of Conveyor Belt Materials Using Listeria monocytogenes as a Model Organism

Persistent Listeria monocytogenes contamination of food industry equipment is a difficult problem to solve. Ultrasonic cleaning offers new possibilities for cleaning conveyors and other equipment that are not easy to clean. Ultrasonic cleaning was tested on three conveyor belt materials: polypropylene, acetal, and stainless steel (cold-rolled, AISI 304). Cleaning efficiency was tested at two temperatures (30 and 45°C) and two cleaning times (30 and 60 s) with two cleaning detergents (KOH, and NaOH combined with KOH). Conveyor belt materials were soiled with milk-based soil and L. monocytogenes strains V1, V3, and B9, and then incubated for 72 h to attach bacteria to surfaces. Ultrasonic cleaning treatments reduced L. monocytogenes counts on stainless steel 4.61 to 5.90 log units; on acetal, 3.37 to 5.55 log units; and on polypropylene, 2.31 to 4.40 log units. The logarithmic reduction differences were statistically analyzed by analysis of variance using Statistical Package for the Social Sciences software. The logarithmic reduction was significantly greater in stainless steel than in plastic materials (P < 0.001 for polypropylene, P = 0.023 for acetal). Higher temperatures enhanced the cleaning efficiency in tested materials. No significant difference occurred between cleaning times. The logarithmic reduction was significantly higher (P = 0.013) in cleaning treatments with potassium hydroxide detergent. In this study, ultrasonic cleaning was efficient for cleaning conveyor belt materials.

Developing Methods for Harvesting Rosy Red Fathead Minnow Eggs

AbstractWe evaluated the effectiveness of different types of spawning substrates in retaining the eggs of rosy red fathead minnow Pimephales promelas, the potential substrate preference of the fish, and the effectiveness of different concentrations of sodium sulfite for detaching eggs from substrates without affecting egg survival. Egg adherence was determined by placing replicate sections of four types of conveyor belt material of varying roughness into a pool stocked with fathead minnow. A screened tray was suspended below each substrate to catch the eggs that did not adhere. Substrate preference was evaluated by following a similar protocol, but only three males were stocked (equal to the number of replicates of each substrate). To test the efficacy of sodium sulfite in removing eggs, substrates with eggs were placed in 0.0, 1.5, and 3.0% solutions and uniformly agitated. The effect of exposure time and egg age was tested by exposing eggs to a 1.5% solution of sodium sulfite for 0 (control), 5, 10, 15, 20, 25, and 30 min. The two rougher substrates retained a significantly greater percentage of eggs than the two smoother ones (72–77% versus 34–39%). Nest locations near the water inlet and air stones were preferred regardless of substrate type. The 1.5% sodium sulfite solution was as effective as the 3.0% solution in removing eggs from substrates. There were no significant differences in hatching rate or percentage of atypical fry resulting from exposure of eggs to 1.5% sodium sulfite for up to 30 min. An egg harvesting system consisting of placing a rough or textured substrate in well‐aerated locations and subsequent egg removal with sodium sulfite appears to be feasible, although economic questions remain.

Transfer of microorganisms, including Listeria monocytogenes, from various materials to beef.

The quantity of microorganisms that may be transferred to a food that comes into contact with a contaminated surface depends on the density of microorganisms on the surface and on the attachment strengths of the microorganisms on the materials. We made repeated contacts between pieces of meat and various surfaces (stainless steel and conveyor belt materials [polyvinyl chloride and polyurethane]), which were conditioned with meat exudate and then were contaminated with Listeria monocytogenes, Staphylococcus sciuri, Pseudomonas putida, or Comamonas sp. Attachment strengths were assessed by the slopes of the two-phase curves obtained by plotting the logarithm of the number of microorganisms transferred against the order number of the contact. These curves were also used to estimate the microbial population on the surface by using the equation of A. Veulemans, E. Jacqmain, and D. Jacqmain (Rev. Ferment. Ind. Aliment. 25:58-65, 1970). The biofilms were characterized according to their physicochemical surface properties and structures. Their exopolysaccharide-producing capacities were assessed from biofilms grown on polystyrene. The L. monocytogenes biofilms attached more strongly to polymers than did the other strains, and attachment strength proved to be weaker on stainless steel than on the two polymers. However, in most cases, it was the population of the biofilms that had the strongest influence on the total number of CFU detached. Although attachment strengths were weaker on stainless steel, this material, carrying a smaller population of bacteria, had a weaker contaminating capacity. In most cases the equation of Veulemans et al. revealed more bacteria than did swabbing the biofilms, and it provided a better assessment of the contaminating potential of the polymeric materials studied here.