By Laurel Maloy, contributing writer, Food Online
The presence of metal fragments in processed food products doesn’t receive the same widespread media attention as pathogenic or bacterial contaminated food. However, the presence of foreign materials is one of the most frequently identified incidences of adulteration in food
Podcast: Best QA Practices In Metal Contamination Control
Ensuring metal-free processed food of any type is an ongoing challenge, one that requires diligent and consistent monitoring. Continual testing of the ingredients, as well as incoming raw material, is only the first step in a foreign material management system. Reducing the incidents to an acceptable level is admirable; however, the goal should be to eliminate the risk for occurrence completely through a clearly defined food safety and internal audit program.
Any internal food safety management program can best be implemented by those who know every step of a certain process. Critical Control Points (CCP) for magnets and metal detection hardware must first be identified, and then maintained properly and verified on no less than an annual basis by a third party. Third-party inspection should include the use of a National Institute of Standards and Technology (NIST)-calibrated Gauss Meter and verification of accuracy. Internal magnet pull tests or portable Gauss meter measurements should be performed frequently, preferably quarterly, or more often. Simply put, the more often magnet performance is evaluated, the more quickly a problem can be identified and corrected.
Numerous factors can affect magnet performance:
- Equipment design — How many and how closely together the magnets are placed determines the strength of the magnetic field. Closer spacing equates to a stronger magnetic field; therefore higher efficiency
- Temperature — Magnets can lose strength when exposed to elevated temperatures. The processing temperatures should be taken into consideration when choosing magnet material
- Product properties — Processing dry, liquid, or moist products will determine the configuration and placement of magnets
- Product flow traits — Flow characteristics can be greatly affected by various factors, especially by humidity, the most common reason for clogged magnetic separators
The FDA’s Health Hazard Evaluation Board recommends regulatory action when metal fragments measuring three tenths of an inch to one inch in size are discovered. The Federal Food, Drug, and Cosmetic Act (FFD&C Act), however, defines food containing a foreign object as adulterated and prohibits interstate commerce of adulterated food products. Medically speaking, metal fragments less than three tenths of an inch in size can cause severe injury or trauma to infants, the elderly, or those who have just undergone surgery. These groups, in particular, are considered at ‘special’ risk. For those not in the special risk groups, ingesting metal fragments of any measurable size can cause laceration of the mouth or throat, dental trauma, and possible perforation of the esophagus, intestines, or stomach.
Most food-processing equipment, if not completely metal, has a number of metal parts. As metal parts, and even the magnets themselves, become worn, damaged, or broken, the opportunity for metal inclusion rises significantly.
Metal Inclusion can enter the process from various sources, including, but not limited to:
- Wire mesh conveyor belts
- Saw blades
- Wire whisk or mixer blades
- Injection needles
- Washers, nuts & bolts
- Mechanical pickers
Inspecting magnets and the findings collection apparatus on a regular schedule, frequently, will provide the first indication of metal entering the process. Analyzing the metal findings may enable the quick identification of the source of the metal fragments. In the event the metal findings do not conclusively determine the source, a thorough equipment inspection may be called for. As a prophylactic measure, regularly inspecting the equipment at any possible point of metal inclusion is prudent. Identifying these points as CCP and the subsequent attention will enable the replacement of worn parts prior to degradation to the point of depositing metal fragments into the process.
Bear in mind that magnets are not the “be all and end all” for the prevention of metal inclusion. Combining magnets with metal detectors is a more effective program, the recommended placement having the magnets upstream to the metal detector. Some processors, depending upon the product, will also employ the use of X-ray equipment as a final stop-gap measure to metal contaminated food reaching the consumer. Any comprehensive Food Safety Management System (FSMS) will include well-defined procedures to prevent, control, correct, and record all possible aspects of food adulteration, including metal inclusion.