10 Apr 2023



Microwave technology is a revolutionary technology that can identify foreign bodies that go undetected by traditional inspection systems

Physical contaminants in packaged food and beverages can harm consumers and cause significant economic and reputational damage. It is not surprising, then, that they are one of the biggest problems facing food companies. However, today’s inspection technologies, such as X-rays and metal detectors, cannot identify all types of foreign bodies, meaning some can get through the production line.

However, using microwave technology to detect physical contaminants makes it possible to overcome the limitations of current technologies and can help companies ensure consumer safety.

Why is a new technology needed to detect physical contaminants in food and beverage products?

Foreign bodies in packaged foods and beverages are an inescapable fact of the production process. Contaminants come from many different sources, including the production line itself (such as pieces of metal in different shapes and sizes), packaging materials (such as glass or plastic), or directly from raw materials that are collected in the field and ground up during production processes. Research from the Rapid Alert System for Food and Feed (RASSF) confirms that many contaminants evade line controls, commonly metal, glass, plastic, wood, rubber, insects, stones, and bones.

Though metal detectors and X-rays are the technologies most widely used to identify contaminates, they are not so effective in identifying materials other than metal.

For this reason, a new technology is needed today: microwaves.

Microwaves can identify contaminants that other technologies cannot, meaning they can help companies ensure compromised products never make it onto the market. This helps brands protect consumers and avoid the economic and reputational damage caused by product withdrawals or recalls.

What operating principle is microwave technology based on?

Microwave technology is based on an innovative principle totally different from X-ray technology. Whereas X-rays detect the difference in density between a product and a contaminant, microwave technology exploits the difference in the dielectric constant between a product and a contaminant. This means it can identify physical contaminants invisible to current X-ray technology, such as wood, plastics, glass, rubber, stones, bones, insects, and metals. (Because all metals are conductive, they have a high dielectric difference with respect to the product).

Microwave technology can also act on other parameters to detect foreign bodies. These include frequency, which is chosen based on the size and type of product and contaminant, and the position of inspection antennas, which are placed around the product and conduct inspections by measuring variations in the electric field caused by the presence of a contaminant.

Such flexibility allows food companies to adapt inspections to any type of package and identify contaminants by penetrating and inspecting every product area. Furthermore, microwaves do not use ionizing radiation, are safe for operators and the working environment, and do not heat the product because it uses little power.

What products can microwave technology be applied to?

To date, microwaves have been tested on liquid and semi-liquid products, which tend to be homogeneous, packaged, or closed. It is expected the technology will be used for other food products soon.

An Artificial Intelligence algorithm is used to carry out microwave inspections. The algorithm learns by inspecting and passing a good (i.e., not contaminated) product, enabling it to avoid false rejects due to the variability of the content or packaging. The system is able to identify the type of contaminant and its position through a 3D reconstruction.

Limitations to the application of microwave technology primarily concern packages completely coated with film or metallic material, such as cans or bricks. Inspection is instead possible using a specific array of antennas for packages that have twist-off caps or aluminized foil on their closures.