Why Is Metal Detection Important in Food? Everything You Need To Know

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Food safety is a major concern for consumers and producers. While we like to think our food is clean, trace metals and particulates can contaminate our food. These unwanted particles mix with our food in processing facilities that employ heavy machinery and handling equipment to sort, package, and move consumables.

With the wear and tear of constant use, these machines can shed metal contaminants into the food products they handle. In 2015 alone, Unibright Foods recalled almost 50,000 pounds of meat in response to discovering “extraneous metal materials” from in-house machinery. Although unfortunate, such incidents remain a helpful reminder of how crucial it can be to use food metal detectors on production lines.

Being able to detect trace metals helps manufacturers prevent contaminated food from reaching consumers and ensures the safety of their products. Understanding what metals to look for and how to detect them are the two first steps to improving food quality at your facility.

Common Contaminants Detected by a Food Metal Detector

Advances in metal detection technology mean these devices can now sense even the slightest quantities of metal. The metal detectors themselves work by picking up on the magnetic permeability or conductivity of metal particulates. There are three main groups of metal types that they detect:

  •     Ferrous Metals (Mild Steel/Cast Iron) Ferrous metals contain iron, an element with strong magnetic properties. Their magnetic properties make these metals especially easy to identify with metal detectors, which pick up on the magnetic field emitted by trace amounts of iron.
  •     Non-Ferrous Metals (Copper/Lead/Aluminum) – These metals lack iron and are not magnetic. However, they are still conductive. The electromagnetic resonances in these metals make them fairly easy to detect.
  •     Stainless Steel – Although stainless steel does contain iron, it does not possess strong magnetic properties. It is also less conductive than the other elements on this list, making it more challenging to detect. Environmental conditions such as moisture and high salinity can also interfere with detection.

X-ray inspection is necessary for non-metallic contaminants such as bone splinters, ceramic shards, stone fragments, and glass, as these particles are neither conductive nor magnetic. In conjunction with food metal detectors, X-ray systems can help detect the full spectrum of particulates found in food.

Types of Food Metal Detectors

conveyor metal detector

Beyond understanding why metal detection is crucial in food processing, it is crucial to know what kinds of food metal detectors are available and how to use them effectively in your production house. The metal detector you need will depend on the kinds of foods you produce, the systems handling that food, and the space available in your facility. Each type analyzes food products with different properties.

  •     Conveyor Metal Detectors – As the name implies, you will find these detectors alongside food conveyor belts transferring food between machines or workstations. These overhead devices scan each item as it passes under the detector’s electromagnetic field, checking each item on the belt line.
  •     Pipeline Metal Detectors – Also known as flow-through detectors, pipeline metal detectors are ideal for checking liquids such as sauces and beverages, which travel through an enclosed pipe. The detector monitors the stream flowing past its sensor for metal contamination and will cut off the flow if it detects contaminants.
  •     Gravity Feed Detectors – Compact and effective, gravity feed detectors are ideal for non-liquid, free-flowing bulk products such as seeds, beans, and powders. Pulled by gravity, these products pass in front of the detector before further processing or packaging.

While these are the primary types of metal detectors, numerous adaptations of these basic systems exist for use in various contexts and environments. Beyond metal detection, certain food metal detector and checker-weight scale combinations allow you to scan for metal contaminants and ensure the consistent weight of your products before they leave the factory.

The Kinds of Food Metal Detectors Used in Different Industries

meat in production line

As we’ve alluded to above, different food metal detectors exist for specific uses across industries. Foods have varying properties and needs, requiring specialized machinery to accommodate their packaging and processing specifications while maintaining sanitary conditions.

Meat Metal Detector

Food metal detectors are essential in the meat processing industry to keep food safe, especially when it comes to raw meat. Meat factories typically process their products in climate-controlled facilities that require regular inspections and cleanings to prevent those products from spoiling. With solid metal products such as steaks, chicken breasts, and other whole parts of the animal, conveyor belt metal detectors are often the device of choice.

Each item must pass through the detector’s magnetic field as it moves across the assembly line for packaging. When metal contaminants are detected, the device automatically stops the belt from continuing, allowing workers to inspect and remove the contaminated meat before it enters circulation.

Spices Metal Detector

Machines in processing plants grind and mash raw spices into fine powders or small grains. The finer the power and the smaller the grain, the more these products act like liquids, requiring a more controlled process to avoid spillage. Due to the homogenous appearance of spices, it is nearly impossible to detect contaminants with the naked eye. Food metal detectors are, therefore, essential.

Gravity feed detectors are the go-to option for spices. As gravity pulls the product through a tubular feed system, the metal detector picks up trace elements of metal particles mixed in with the flow.

Biscuits Metal Detector

Industrial bakeries also commonly employ food metal detectors to ensure their products are contaminant-free before shipping them off for consumption by the public. There are numerous steps in the baking process, and the product interacts with many different machines and conveyor systems.

The increased exposure to heavy machinery heightens the odds of unwanted metal particles mixing with the food. From chips to pretzels, cookies to bread, industry professionals recommend placing detectors at the end of the production line after packaging.

Other Industries

When we think of consumables, the food industry is usually the first thing that comes to mind. However, other industry sectors employ food metal detectors for consumable goods. Two of the most prominent are the cosmetic industry and the pharmaceutical industry.

Just like meat and baked goods, pills and medicine face strict regulations as consumable products and are equally susceptible to metal contaminants during the production process. While detectors for medicine can differ from those for meat and other food products, the underlying principle is the same.

Factors That Can Affect Food Metal Detection Results

Historically, mineral-rich foods such as leafy greens, salty meats, and cheeses were capable of setting off a metal detector due to their naturally occurring mineral content. Likewise, the temperature of a food processing facility and the salinity of the air could often interfere with the results. The same was true of the electromagnetic fields generated by large machinery near the detector.

Thankfully, recent advances in metal detection technology have bypassed these interference issues, allowing operators to tune out unrelated signals and focus on specific elements and frequencies. Smart detection technology can scan frequencies between 50-1000 kHz, enabling food processing plants to detect incredibly low quantities of metal in food.

Before using a food metal detector at the end of a production line, always check whether your food packaging contains aluminum foil or other metals. While not in the food itself, the packaging material can still set off your device, causing false positives. To ensure the proper application of a food metal detector in your facility, request a product test by one of the manufacturer’s certified inspectors. The inspector can test the device’s performance in your factory, fine-tuning it to that environment.

Where Should You Put the Metal Detector for Best Results?

operator checking quality of the product after being checked by a food metal detector

Understanding where to put a metal detector in a food processing facility is vital to using it effectively. Since contaminants can enter at almost any point in the production line, industry consensus dictates that the best location for a detector is at the end of the process. Placing the device in the incorrect location can render it ineffective and lead to unwanted contaminants going unnoticed.

However, this is only half right. Most food safety experts recommend installing metal detectors at the beginning and end of the food processing line. This way, producers can better understand where, how, and when contaminants are getting into the food during production.

If food enters the production line and passes the first detector but fails the second detector, a factory manager will know that the contamination occurred during the production process and not from the raw ingredients. Experts can better pinpoint the exact source and prevent future contaminations with this knowledge.

How To Choose the Right Metal Detector for Your Application

Increasing numbers of food developers recognize the need for food metal detectors in all stages of the food production process. Consequently, the market is expanding rapidly, prompting the development of more and more detectors specially designed for various needs and purposes. With these developments come improved technology and a wider selection of features.

Before purchasing a food metal detector, it is important to know where the detector will fit in your existing system and how to use it most effectively. Even within the shortlist of detectors (conveyorized, gravity feed, and pipeline) we provided above, there are many machines spanning the gamut of size, design, and functionality. From conveyorized to flow-through systems, you can customize some detectors to your needs, whether you’re a small independent food company or a corporate giant.

At TDI, we understand why metal detection is so important to the food industry. With our years of experience producing and installing quality detectors, we have the tools and knowledge to help you determine the most suitable metal detector for your system. Whether you’re a meat producer, a fruit packaging facility, or a pharmaceutical company, our machines will keep up with your fast-paced work environment, providing you with reliable data on the levels of metal contaminants in your food.

We design our metal detectors to your specifications and with your customers’ safety in mind. Our experts are on hand to find the perfect food metal detector to meet the needs of your production facility. To find out more about what TDI can do for your business, call us now at 877-834-6750 or send us an email through our website.

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