In recent years, foreign material present in food products have comprised a large root cause of recalls. Plastic, metal, wood, and other extraneous items are commonly found, as reported in various regulatory agency published incident reports. While the source of the foreign material contamination often varies across each product category, and may often be unknown, incident investigations have pointed towards process inputs and materials, equipment, and tools as contributing factors. As with all factors, the design and maintenance of processing equipment has become more heavily scrutinized as a means to mitigate associated risk.
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Explore This IssueDecember/January 2019
The prevention of food product contamination resulting from foreign material associated with equipment begins with a basic understanding of sanitary design. Once this foundation is established, methodologies to assess and quantify risk to the product can be determined. Control measures, including redesign, can subsequently be implemented to address any identified high-risk concerns.
Counting on Sanitary Design
Sanitary design is often defined as the process by which equipment and facilities are designed or reconfigured to enable effective cleaning, inspection, and preventative maintenance in an effort to reduce risk in three critical areas: physical (foreign materials), biological, and chemical. Food manufacturers need to develop sanitary design programs that seek to reduce overall risk associated with the three risk types. Internal programs and standards based on historical manufacturing risk and recommendations from industry associations provide the foundation for effective food safety control associated with equipment design. Several food industry organizations publish sanitary design recommendations for reduction in adverse food safety incidents. Examples of these include the North American Meat Institute (NAMI), 3-A Sanitary Standards Inc., and the European Hygienic Engineering Design Group.
Examples of basic elements of sanitary design programs that seek to address common equipment design risks include:
- Wear points and friction zones;
- Material selection and compatibility;
- Locations of critical components;
- Surface finishes and welding; and
- Ease of inspection and maintenance.
Wear points and friction zones on equipment are critical areas where foreign material contamination may arise. Design programs seek to identify and reduce the prevalence of these areas during operations. Common cases include plastic on plastic (conveyor belts with support or diversion guides), metal on plastic (wire belts with plastic guides), and metal on metal (grinding knives and plates). Many sources of wear and friction stem from improper setup, inadequate maintenance, or misalignment. Careful consideration should also be placed on how food product may induce additional wear on equipment components—for instance, grinding frozen meat—and how the specific equipment operates over the course of a production timeframe. A best practice recommendation is to catalog points of wear and friction on equipment to allow for further analysis and preventative measures.
Selecting the proper equipment materials and understanding overall compatibility with all aspects of the manufacturing process is also a key point to consider. Typical industry guidance as noted from the NAMI sanitary design checklist includes:
- Metals should be stainless steel and appropriate for the process;
- Composites, plastics, and synthetics are made of metal detectable materials (compliant to CFR 21 175-177) and limited in use in product zones;
- Coated, plated, or painted surfaces are not utilized in product zones;
- Exposed fibers are not utilized; and
- Selected materials are compatible with each other.
For instance, improper metals (uncoated aluminum, carbon steel, etc.) likely to become corroded during the chemical sanitation process pose a risk through flaking and premature failure. Considerations must also be taken for anticipated temperatures, process characteristics, and production runtime when selecting components.
The placement of components utilized in the construction of processing equipment is of high concern and should be thoroughly reviewed. Component failure or breakage is often attributed to foreign material incidents. Items that pose a risk of breakage, falling off, or failure should not be located in the product zone. Examples of items that should be mounted outside of product zones include, but are not limited to, electrical items (switches, e-stops, sensors, panels, conduit, cables, etc.), mechanical items (motors, gearboxes, drives, bearings, etc.), identification items (name tags, plates, labels, etc.), and fasteners.
An additional aspect of design is the inspection of surface roughness/finish and welding. Rough surface textures increase friction on components in contact with each other and are more prone to excessive wear. Welding poses much of the same risk if burrs, improper polishing, and poor technique are present.
Often overlooked is the level of clearance in and around equipment, particularly in the product zones. Full access to equipment while performing preventative maintenance tasks to ensure proper function is important to eliminate premature failure or breakage. Providing adequate distance allows employees to inspect equipment throughout production operations for integrity, alignment, and setup.
Understanding overall foreign material risk requires both an analysis of the process environment and of the equipment itself. Characteristics of the process environment to consider when determining foreign material risk include, but are not limited to, product exposure status or zones, location of equipment on the production line, detection methods throughout the production line, and frequency of equipment inspection.
The concept of zones is of particular importance as it pertains to exposure of the product to components in the equipment. Product zones where direct contamination can occur are inherently higher risk than non-product zones on equipment or facility infrastructure. Risk management efforts are thus first focused on higher risk product zones.
The location of a selected piece of equipment within the production line also determines the level of risk associated with the process. The amount or volume of product that could potentially be affected if a foreign material incident occurs should be taken into consideration. Upstream grinding operations that feed numerous lines are higher risk than a single line where product is already formed or packaged, see Table 1.
The type and quantity of detection methods present throughout the production line can impact overall risk. Methods such as X-ray are able to detect a wider scope of materials than a simple metal detector or visual inspection and would lower total process risk. Having multiple devices, such as X-rays, spread out over the process would also lower risk.
Similar analysis could be applied to the frequency of equipment inspections performed during operations. Equipment that is continuously inspected for integrity present lower process risk than those items only inspected prior to startup.
Equipment Design Characteristics
As when assessing risks associated with certain process characteristics, a similar structure can be used when analyzing sanitary design for foreign material. Examples pertaining to metal selection in a chemically cleaned environment are demonstrated in Table 2.
Other sanitary design specifications as defined by various industry organizations can also be placed on a spectrum of risk for further analysis.
Quantifying Overall Foreign Material Risk
Once an assessment of all the various risk factors has been undertaken, numerically quantifying given risk can be helpful to determine priority of corrective actions and preventative measures.
A simple method to numerical rank risk is using a 1-10 scale, where a high-risk item or characteristic would be assigned a number 10 and lower risk items or characteristics would be assigned a lower number.
The example process risk factors described earlier could then be assigned a number in a table, after which the average of process risk can be computed, see Table 3.
Adding the process risk rating with the assigned sanitary design risk rating would give a total overall sum of risk.
Equipment and associated components can pose a risk for foreign material through various physical means. Understanding sanitary design factors allows for the ability to assess and quantify risk and subsequent actions needed to bring the system into appropriate control.
Davis is corporate sanitation manager at OSI Group, LLC. Reach him at Jadavis@osigroup.com.