Metal Detection in the Food Industry

Since the agricultural revolution thousands of years ago, when humans moved away from their nomadic, hunter-gatherer roots and embraced permanent settlements and farming, the process of getting food from producers to consumers has become ever more complex. Nowadays, the food industry consists of a vast, sprawling network of seed producers, planters and harvesters, livestock, transportation, refrigeration, and many different kinds of processing before food hits the grocery store shelves.

It’s a multi-billion-dollar industry, and because humans will always need to be fed, it’s one that will continue to be vital as populations increase. An important consideration, more so than in other industries, is safety – if the food we put into our bodies is contaminated, then people get sick, lose confidence in their food supply, and the brand suffers as a result. Everyone has experienced mass recalls of products, and with food, the perception of taint can linger long after the original problem has been resolved.

Screening out Metal

One of the most common contaminants in food products – or in fact in any products that go through industrial processing – is metal. Metal fragments can come from a variety of sources, from bits of farm tools that break while food is being harvested, to parts of robotic systems that break during processing. Worse, the more processing food undergoes, the worse the problem gets, because relatively large and easy to find pieces of metal can get broken down into smaller pieces that may escape visual checks by workers, right up until the moment a consumer breaks a tooth on their peanut butter.

It’s important then to ensure that metal is screened out of processed food as early as possible. Industrial metal detectors are widely used in food processing to allow this to happen. If the metal fragments can be screened out early enough, there is a much better chance of reducing contamination. The biggest advantage of metal detectors is their simplicity – they really just require a couple of coils of wire to work. (Essentially, a current is passed through a transmitter coil, which induces a magnetic field; the field then induces a current in nearby pieces of metal, which creates its own magnetic field, which can be picked up by the detector’s receiver coil, creating a current and highlighting a detection event.)

Where to Place Detectors

As mentioned, it’s important to screen out metal early so that you don’t end up with smaller, more difficult to detect pieces down the line. With that in mind, a good starting point is to place detectors immediately after the raw food has been harvested and is ready for processing. But that’s only the beginning. Because of the multiple steps involved in food processing, it also makes sense to place detectors throughout the process. Not only will this help keep the product free from contamination, it also allows the quick detection of potential problems with machinery – for example, if pieces of an industrial machine have broken off and are now residing in the product, it’s important for the operators to know this as soon as possible so that the machine can be repaired.

Depending on the type of food, different types of detectors can be used. For example, for food moving along a conveyor belt, conveyor system metal detectors can be used to examine the product. Similarly, detectors exist for free-fall or gravity system environments, as well as pipeline/pumped systems (for liquid goods). If you have an especially high throughput, bulk system detectors are available that can scan 50–100 lbs of product at once.

Detectors should also be placed just before the food is sent out to its final destination. These days, even food packaged in foil can be checked using a metal detector, if you have one of sufficient complexity.

Are Detectors Mandatory?

Technically, metal detectors are not mandatory – but they are highly  recommended, because of their cost and simplicity, and because of how common metal contamination in food can be. Of course, metal isn’t the only potential contaminant. Physical contaminants, as well as metal, include wood, glass, hair, or paint chips. Chemical contaminants can include cleaning, maintenance or pest control chemicals. And biological contaminants can include microorganisms and insects, as well as rodents and sometimes birds.

Metal detectors, of course, will not screen out most of these things. The most common alternative used to screen out physical contaminants is probably X-ray detection, which can identify metal as well, but tends to be more expensive and carries risks such as exposure to ionizing radiation. They will however generally spot larger biological contaminants, but cannot detect chemical contaminants or microorganisms.

Conclusion

Metal detectors are important in the food industry because metal is the most common kind of contaminant and such detectors are relatively inexpensive. They should be placed at various points in the food production process for optimum efficiency, though it is worth noting that they cannot screen out every kind of contaminant. Nevertheless, they are an important and effective tool that can be used to reduce contamination in food.