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The Pathogen Risks on Your Plant’s Floor

June 1, 2021
Assess and manage the dangers of food processing floors with effective sanitation practices.

Adverse food safety incidents resulting in product loss and market withdrawals present a significant business risk to food manufacturers today. Increasing expectations from consumers and regulatory agencies have propelled food safety to critical importance.

Pathogens present in food products comprise a large portion of recalls in the U.S. While the source of the contamination often varies across each product category, and may often be unknown, pathogen prevalence in the processing environment may permit indirect contamination from processing floors to surrounding surfaces.

Given the pathogen risk associated with floors, the critical importance of proper design, maintenance and sanitation of these surfaces has become increasingly recognized.

Hygienic design of floors

A basic understanding of the key principles of proper hygienic design of processing floors is important for identifying where risks may occur and, subsequently, during the implementation of sanitation best-practices. Previously established basic principles of equipment and facility hygienic design can, similarly, be applied to floors when assessing food safety risks.

Cleanable to a Microbiological Level: Processing floors must be constructed to ensure effective and efficient cleaning over the lifespan of the installation. Floor design should prevent microbial contamination on all surfaces and be validated and routinely verified to be effective.

Environmental monitoring programs should include routine sampling of floors where harborage or transfer of pathogens may occur, such as identified hygienic design constraints, high-use traffic areas (e.g., walkways) or consistently moist areas.

Visual inspections of overall floor integrity, inclusive of associated junction points, should be undertaken on a periodic basis. Where issues are noted, they should be repaired as soon as possible, followed by intensive environmental monitoring activities to confirm acceptability.

Made of Compatible Materials: Construction materials used for floors must be compatible with the process, environment, chemicals and the methods of sanitation. Materials utilized in construction thus must be inert, chemical resistant, nonporous and nonabsorbent.

Various aspects of the food manufacturing process can impart adverse effects onto flooring surfaces if not carefully evaluated. Consistent exposure to water and chemicals, such as strong acids or bases as often utilized during the sanitation process, can lead to delamination or other failures in the substrate or exposed floor layer.

Additionally, consideration must be given to the extent of traffic, thermal cycling, heavy loads (e.g., forklifts) and impacts from the movement or dropping of equipment. Insufficient thickness of floor coatings under these conditions can lead to excessive wear, contributing to pathogen harborage. Generally, coatings such as heavy-duty polyurethane resins or vitrified tiles, of varying thickness dependent on conditions described above, are commonly utilized.

Accessible for Inspection, Maintenance and Sanitation: Areas of processing floors must be readily accessible for routine inspection, maintenance and sanitation. Equipment should be sufficiently elevated off the floor surface to permit execution of the sanitation process, as well as to allow for proper inspection and monitoring requirements.

Generally, stationary equipment should be elevated at minimum 12 inches off the floor surface, contingent on equipment dimensions and presence of any product contact surfaces. Large pieces of equipment, such as spiral freezers and ovens, should be elevated higher off the floor surface in comparison to smaller items, such as conveyors.

Adequate Drainage to Prevent Liquid Collection: Floors must be self-draining to ensure that liquid does not accumulate, pool or otherwise collect on surfaces. Typically, in wet environments, a slope of 2% is recommended, whereas in dry environments a slope of 1% is often utilized. Additionally, liquids generated from equipment or other structures should be directly discharged to drains and not permitted to flow across floor surfaces.

Hygienic Equipment Installation: Equipment and other structures must be installed in a manner that does not impede the drainage of liquids or otherwise present a food safety risk. Installed equipment must not be placed directly on drains or drain covers and sufficiently separated from these areas to ensure compliance to accessibility requirements. Product contact surfaces of food processing equipment should be elevated at minimum 18 inches off the floor to prevent incidental contamination from any splashing or aerosolizing of liquids.

Elimination of Harborage Points: Floors must be free of harborage points such as pits, cracks, crevices, open seams, gaps, excessive roughness and sharp corners at junction points. Junction points on floors, such as the interface between drains, walls and other floor sections, are often points for harborage of pathogens and must be fully sealed and routinely inspected.

Bases of drains inset within floors must be properly supported to prevent settling. Junction points between floors and vertical structures, such as walls or support beams, must have a sufficient radius, such as through the use of a cove, to prevent debris from being trapped.

Hygienic Operational Performance: During normal operations, floors must be maintained in a manner that does not contribute to unsanitary conditions or facilitate the harborage and growth of bacteria. Food residue or other debris generated during manufacturing operations must be removed by personnel on a timely basis from floors to prevent any blockage of drains or employee safety incidents.

Where expansion joints are utilized to prevent irregular cracking from thermal cycling, their use should be limited to the smallest extent possible and installed away from identified high-risk zones in the processing area.

Hygienic Zone Separation: Physical separation must be maintained to reduce the likelihood of transfer of microbial hazards from low-risk process areas to high-risk (i.e., pathogen controlled) process areas. Facilities should implement the use of active barriers (e.g., controlled access doors, walls) with cleaning and sanitizing interventions, such as boot scrubbers and entryway foamers, to prevent introduction of pathogens from employees’ shoes and transferred equipment or supplies.

Compatibility with Installed Plant Systems: Installed existing plant sub-systems, such as for drainage, or automated cleaning systems (e.g., CIP), must not present food safety risks due to soil or liquid loads, operational conditions or standard sanitation operating procedures. Floor drainage systems must be sized appropriately to ensure liquids or waste materials are removed from floors in a timely manner without exceeding the installed capacity.

Validated Sanitation Protocols: Procedures for cleaning and sanitation must be clearly written, efficient, proven effective and compatible with the equipment and the manufacturing environment. Sanitation protocols developed for processing floors must be validated and routinely verified through the use of established pre-operational monitoring activities, such as visual inspections and surface microbial sampling, to ensure the selected cleaning process is adequate to achieve hygiene goals.

Adjustments to the sanitation process should be made when observed inspections and collected data taken post-sanitation show a downward performance trend. Additional sanitation strategies are often necessary to add in areas designated high-risk, such as in ready-to-eat (RTE) or fully-cooked processes.

Sanitation best-practices for floors

Along with ensuring appropriate hygienic design, implementing effective sanitation measures for floor surfaces is critical in the maintenance of food-safe conditions in the processing area. The Seven Steps of Wet Sanitation is the defined industry best-practice sequence of actions during routine cleaning where water is utilized.

The process is divided into distinct steps that are to be completed sequentially, and in a synchronous manner, across the processing area. While the best-practices describe actions for the entire processing area (i.e., equipment) under the scope of sanitation, critical focus areas and optimal techniques specific for floor cleaning are important aspects contained within each step.

Step 1: Prepare Area and Dry Clean. In this step, sanitation personnel must ensure that gross debris generated during the production process is adequately removed from floors and drains prior to any application of water to prevent pooling or drainage issues in subsequent steps. Personal protective equipment (PPE), supplies and tools, such as shovels or squeegees, are to be dedicated for floor-use only, such as via color-coding, to prevent contamination of equipment and other processing areas.

Step 2: Pre-Rinse of Soils. The initial hot water rinse of soils is to occur in a top-to-bottom manner. When rinsing floors and drains, it is important to limit water pressure to the lowest setting possible, while maintaining effectiveness, to minimize the potential for aerosolizing soils and liquids that may contaminate the processing area.

Step 3: Detergent Application and Scrub. Detergent is to be applied in a bottom-to-top manner, using a side-to-side sweeping motion. The texture of the foam must be monitored and applied consistently to ensure that all surfaces of the floors are coated. Additionally during this step, drains are to be cleaned by a dedicated sanitor with separate PPE and tools. For tough soils on floors, manual scrubbing, for instance with a long-handled brush dedicated for the application, may be utilized. It is advised not to use automated floor scrubbers in high-risk areas due to the observed difficulty in maintaining the machines in pathogen-free conditions.

Step 4: Post-Rinse and Self-Check. To remove detergents and residual soils, surfaces should be rinsed in a top-to-bottom manner using a low-pressure, high-volume flood method to limit overspray and aerosols, particularly on floor surfaces. After completion of the final rinse, sanitors are to inspect their work to ensure floors are free of visible residues or debris. Repetition of the chemical sanitation cycle should occur where deficiencies are observed.

Step 5: Prepare for Pre-operational Inspection. During this stage of the sanitation process, any standing water on floor surfaces must be removed with a dedicated tool appropriate for the task (e.g., squeegee) and performed in a manner that does not contaminate adjacent equipment surfaces. Sanitors must wash hands and change into clean PPE prior to proceeding with subsequent steps.

Step 6: Pre-Operational Inspection. Floors and associated infrastructure surfaces, such as drains, should be included in the facility pre-operational monitoring program. To avoid contamination, floor surfaces and, subsequently, drains must be inspected following completion of equipment and other infrastructure surface inspections. Where soils are observed, corrective actions must be taken and found acceptable before proceeding. As a best-practice, floors and drains should also be included in pre-operational surface sampling for soils (i.e., ATP monitoring) and microorganisms (e.g. APC or TPC). Failures indicate the necessity to re-evaluate the sanitation process.

Step 7: Sanitize. During the sanitizing process, it is recommended that facilities utilize a higher concentration of chemical for floors (e.g., 800-1000ppm QAC) than is typically utilized for food product contact surfaces. Sanitizers utilized for floor surfaces should be foam-applied to ensure adequate coverage and to allow for greater contact time. Typically, sanitizers applied to floors should be allowed to remain on surfaces without being rinsed off, permitting a residual effect following application.

Additionally, in recent years, high-risk processing facilities have increasingly implemented the use of dry sanitizing powders, such as QACs or alkaline peroxides, at the conclusion of sanitation as a preventative measure. When utilized on floor surfaces with adequate moisture to ensure activation, these products have proven effective for pathogen control in high-traffic zones or where hygienic design constraints have been identified.

James T. Davis is the Global Sanitation Director at OSI, leading the company efforts in sanitation and hygienic design of equipment and facilities, with emphasis on food safety risk management. In this role, he develops and implements standards, training and policies to drive consistency in sanitation and hygienic design ensuring a high level of food safety for the organization. James collaborates and participates in industry associations to develop and implement best-practices and new standards.

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