FlexXray Blog

The Complete Guide to Metal Detection Services in the Food Industry

Posted by Chris Keith on Aug 22, 2019 8:15:00 AM

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As food becomes more processed, the risk of foreign contaminants finding their way into edible products increases. Each step in the production line presents one more opportunity for contamination, either through human or mechanical error. Metal detection services can help prevent metal fragments hidden in food from reaching consumers and provides a way to find slivers of different metals that would be missed throughout the production process.

Metal Detection in the Food Industry

While the increasing number of food recalls makes it appear that incidents of contamination are on the rise, many in the industry attribute the higher recall numbers to the improved ability of machines to detect foreign particles and flag the contaminated product.

One of the most common forms of physical contaminants is metal. This type of contamination can occur at many different stages of the production cycle, including:

  • In the field
  • During processing
  • During the packaging process

Food manufacturers must pay particular attention to this type of contamination and have processes in place to detect it.

How Metal Detection Works

Implementing metal detection in the production process is an effective way to ensure that your food is metal-free.

  • While X-ray inspection has emerged as a successful solution for finding all types and smaller sizes of foreign contaminants, metal detection is ideal in situations where you’re looking specifically for metal fragments and aren’t concerned with other types of contamination.
  • Metal detectors look for signal interferences, which means that non-conductive products are a better fit for greater metal detection sensitivities.
  • When metal is hidden in a dry, non-conductive product, such as pasta or bread, it’s easy for the metal detector to locate it.
  • In these ideal situations, the metal detector can find metal fragments that are even smaller than what can be seen by the human eye, because it’s able to recognize the sensitive interference in signal.

woman using metal detector machine

Types of Metal Contaminants in Food

When it comes to physical hazards in food, there are three types of metal contaminants:

  • Ferrous: The easiest type of metal to find, because it is both magnetic and conductive
  • Non-ferrous: Although it is not magnetic, non-ferrous metal is a good conductor, which makes it relatively easy to find
  • Stainless steel: Very low conductivity, which means it is the most difficult to detect with metal detection technology

In addition to being affected by the magnetic and electrical properties of the contaminant, metal detectors can be thrown off by materials with a high volume of water or salt, which interferes with the signal.

When a "wet" product is frozen, however, it changes the conductive properties of the product and makes it easier to detect the presence of metal.

For example, a fresh chicken breast has a high volume of water, which makes finding metal fragments a challenge. However, when the chicken is flash frozen, it changes the conductivity and makes it easier to detect metal fragments.

When to Use Metal Detection

Metal detection can be implemented at any stage in the production process and can be used again at the end of the process for greater assurance. It’s particularly effective when used early in food production, such as when blending dry ingredients.

This early stage is the fastest and most cost-effective stage to find contaminants, in that it allows you to minimize waste and find metal contaminants before other ingredients are added — which must then be disposed of or reworked because of contamination.

Each manufacturer can use the Hazard Analysis and Critical Control Point (HACCP) system for evaluating their processes and determining where in the process contamination might occur.

Depending on whether that’s at the beginning of the process, right after ingredients are mixed, after a container is filled or at the end of the line will help determine when the metal detection should be used.

When multiple ingredients are used and a considerable amount of processing is involved, it’s always advisable to have it tested for metal at the end of the process.

In such cases, many manufacturers choose to have their food X-rayed as well, since a large number of ingredients increases the likelihood of contamination — and it might not always be a metal contaminant.

Metal Detection and Packaging

Packaging continues to play a role in contamination detection but also can raise concerns over whether the packaging itself contributes to contamination.

Metal detectors cannot be used on packaging that contains metallic elements, which can become a challenge since metalized film, foil-based packaging and metal lids are widely used. For foods packaged in metalized containers, metal detection must be done before packaging.

Choosing the proper detection and inspection system is a decision facing all food quality professionals. When your only concern is metal contamination, a metal detection system could be your best option.

However, if you also have concerns about finding substances such as glass, bone, stone, plastic, rubber and more, you may want to consider X-ray inspection services.

For absolute assurance and peace of mind, using both metal detection and X-ray inspection at different stages of the process is your best bet.

In doing so, you can know that your product is safe — which means your customers and your brand’s reputation are safe, too.

case study foreign material problem contaminant x-ray

Topics: X-ray Food Inspection, Product Packaging, Processed Foods

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