Metal Detection – Understand The Potential Hazard
Ingesting metal fragments can cause injury to a consumer, injuries that could include dental damage, laceration of the mouth or throat, or laceration or perforation of the intestine.
The US Food and Drug Administration’s (US FDA) Health Hazard Evaluation Board has supported regulatory action against products with metal fragments from 0.3 inch (7 mm) to 1 inch (25 mm) in length. The Federal Food, Drug, and Cosmetic Act (FFD&C Act) prohibits interstate commerce of adulterated foods (21 U.S.C. 331). Under the FFD&C Act, food containing foreign objects is considered adulterated (21 U.S.C 342). See the FDA’s “Compliance Policy Guide,” Sec. 555.425. In addition, foreign objects that are less than 0.3 inch (7 mm) long may cause trauma or serious injury to consumers in special risk groups, such as infants, surgery patients and the elderly.
Metal-to-metal contact (e.g. mechanical cutting or blending operations and can openers) and equipment with metal parts that can break loose (e.g. moving wire mesh belts, injection needles, screens and portion control equipment, and metal ties) are likely sources of metal that may enter food during processing.
Control Of Metal Inclusion
Once introduced into a product, metal fragments may be removed by passing it through a screen, magnet, or flotation tank. The effectiveness of these measures depends on the nature of the product. For example, these measures are more likely to be effective in liquids, powders, and similar products in which the metal fragment will not become embedded.
Alternatively, metal fragments may be detected in finished food products by an electronic metal detector. The use of electronic metal detectors is complex, especially with regard to stainless steel, which is difficult to detect. The orientation of a metal object in food affects the ability of equipment to detect it. For example, if a detector is not properly calibrated and is set to detect a sphere 0.08 inch (2 mm) in diameter, it may fail to detect a stainless steel wire that is smaller in diameter but up to 0.9 inch (24 mm) long, depending on the orientation of the wire as it travels through the detector. Processing factors, such as ambient humidity or product acidity, may affect the conductivity of the product and create an interference signal that has the potential to mask metal inclusion unless the detector is properly calibrated. These factors should be considered when calibrating and using this equipment.
Finally, the hazard of metal inclusion may also be controlled by periodically examining processing equipment for damage that can contribute metal fragments to the product. This measure will not necessarily prevent metal fragment contamination, but it will enable you to separate products that may have been exposed to metal fragments. However, visual inspections of equipment for damaged or missing parts may only be feasible with relatively simple equipment, such as band saws, small orbital blenders, and wire mesh belts. More complex equipment containing many parts, some of which may not be readily visible, may not be suitable for visual inspection and may require controls such as metal detection or separation.
Determine Whether The Potential Hazard Is Significant
The following guidance will assist you in determining whether metal inclusion is a significant hazard at a specific processing step: Is it reasonably likely that metal fragments will be introduced at this processing step (e.g. do they come in with the raw material or will the process introduce them)?
- For example, under ordinary circumstances, would it be reasonable to expect that metal fragments could enter the process as a result of worn, damaged, or broken equipment parts from the following sources (this list is not exhaustive):
- Mechanical crabmeat pickers
- Wire-mesh belts used to convey products
- Saw blades used to cut portions or steaks
- Wire from mechanical mixer blades
- Blades on mechanical chopping, filleting, or blending equipment
- Rings, washers, nuts, or bolts from breading, batter, sauce cooling, liquid dispensing, and portioning equipment, etc.
Metal inclusion should also be considered a significant hazard at any processing step where a preventive measure, is or can be used, to prevent or eliminate the hazard (or is adequate to reduce the likelihood of its occurrence to an acceptable level), if it is reasonably likely to occur. Preventive measures for metal inclusion can include:
- Periodically checking equipment for damaged or missing parts
- Passing the product through metal detection or separation equipment
- Control of metal inclusion
In most cases, you should assume that the product will be consumed in a way that would not eliminate any metal fragments that may be introduced during the process. However, in some cases, if you have assurance that the product will be run through a metal detector for detection of metal fragments, or through screens or a magnet for separation of metal fragments by a subsequent processor, you would not need to identify metal inclusion as a significant hazard.
Identify Critical Control Points
The following guidance will also assist you in determining whether a processing step is a critical control point (CCP) for metal inclusion:
- Will the product be run through a metal detector or a separation device, such as a screen, magnet, or flotation tank, on or after the last step where metal inclusion is identified as a significant hazard?
- If it will be, you should identify final metal detection or separation as the CCP. Then processing steps prior to metal detection or separation would not require controls and would not need to be identified as CCPs for the hazard of metal fragments. You should recognize that by setting the CCP at or near the end of the process, rather than at the point of potential metal fragment entry into the process, you are likely to have more labor and materials invested in the product before the problem is detected or prevented.
- If the product will not be run through such a device, you should have procedures to periodically check the processing equipment for damage or lost parts at each processing step where metal inclusion is identified as a significant hazard. In this case, you should identify those processing steps as CCPs.
For the complete range of SGS services and support visit SGS Food and Safety.Zeb Blanton
Global Technical Manager-Food
t: +1 407 682 4720