Surge in Food Recalls Highlights the Importance of Advanced Inspection Technologies

This Spring has not been a good month for packaged foods. USDA food recalls for physical contaminants – including metal, wood, and plastic pieces – involved hundreds of thousands of packaged products containing meats, soups, and even herbs.

Food manufacturers use two main types of technologies to inspect their products to help ensure safety when it comes to avoiding – or detecting – physical contaminants in their packaged foods:

Metal Detection:
- Use of metal detectors to identify and remove ferrous, non-ferrous, or stainless steel contaminants from food production lines.
X-ray Inspection:
- X-ray inspection machines detect physical contaminants, both metallic and non-metallic such as glass, stones, and dense plastics, as well as check for product integrity and fill levels.

The Critical Role of Metal Detectors in Food Manufacturing

Metal detectors are an essential tool in the food industry, used at various stages of the production process to help ensure that metal contaminants are detected and removed before the food products reach consumers. They are employed during raw material inspection, before processing to check for metal contaminants, and at critical control points within the production line to continuously monitor for metal contamination. Additionally, metal detectors are used post-processing, after the food has been processed but before packaging, to help ensure no metal has been introduced during processing. Finally, they are used for final product inspection, after packaging, to help ensure the final product is free from metal contaminants before it is shipped to retailers or consumers.

Metal detectors work by creating an electromagnetic field using a coil system. When a metal contaminant passes through this field, it disrupts the field, and this disruption is detected by the system. The detector processes the signal caused by the disruption to determine the presence of metal, whether ferrous, non-ferrous, or stainless steel. If metal is detected, the system triggers a rejection mechanism, such as a pneumatic pusher or a diverter arm, to remove the contaminated product from the production line. (You can read about metal detector technology here.)

Enhancing Food Safety with X-ray Inspection Systems

X-ray inspection systems are utilized in the food industry at various stages of the production process to help ensure the safety and quality of food products by detecting physical contaminants and verifying product integrity. These systems are typically employed during the final stages of production, after the food has been processed and packaged, to inspect the finished products before they are shipped to retailers or consumers. They can also be used at critical control points within the production line to continuously monitor for contaminants and help ensure consistent product quality.

X-ray inspection systems work by generating X-rays that pass through the food product. As the X-rays penetrate the product, they are absorbed at different rates depending on the density and composition of the materials within the product. The system captures images based on the varying absorption levels, which allows it to identify foreign objects such as glass, stones, metal, and dense plastics that may be present in the food. Additionally, these systems can check for product integrity, verify fill levels, and detect packaging defects.

The captured images are processed by sophisticated software that analyzes the data to detect any anomalies or contaminants. If a contaminant is detected, the system can trigger a rejection mechanism to remove the affected product from the production line. (Learn about X-ray inspection system technology here.)

Why Product Effect Should Be Considered with Metal Detectors

There are key barriers to achieving 100% contaminant-free products:

The metal detector must find anything, anywhere in any product all the time. That can be daunting considering the volume of production from just one line in a day and all the different types of metal pieces that might be part of your factory or inherently included within raw ingredients.
Metal detectors use electromagnetic fields to find things that are magnetic and conductive. Some food products are wet, have salt or contain minerals, which when subjected to electromagnetic fields also look magnetic and conductive and will lead to false rejects. Ignoring the product and finding the metal is not as easy as it seems.

Small metal foreign contaminants have very small signals, and the metal detector is operating in a factory that has many possible noise sources that can confuse the metal detector electronics and software. For example, at any given time:

Large motors are turning on and off
Electronics boxes are broadcasting wide spectrums of radiated noise
Production equipment is vibrating and causing the antenna in the metal detector to move ever so slightly
Electrical power is surging and dropping
Temperatures are going from freezing to boiling and back again

Because of these challenges, advanced technology has been developed and is in use today. (As an example, the Thermo Scientific™ Sentinel™ multiscan food metal detector uses a true spectrum of frequencies along with new signal processing, thus reducing the probability of a contaminant escape to zero. It scans up to five completely adjustable frequencies to find metal types and sizes previously undetectable. It’s like having up to five metal detectors back to back in a production line. It reduces the probability of an escape by many orders of magnitude. You can read more about multiscan technology in the white paper Why Multiscanning Technology Improves Metal Detection and Food Safety.)

Choosing the Appropriate X-ray Inspection System

While X-ray inspection systems are highly effective in detecting a wide range of physical contaminants in packaged foods, they do have certain limitations and may not catch all types of contaminants. X-ray systems work by generating X-rays that pass through the food product, and the varying absorption levels of different materials create images that can be analyzed for anomalies. However, the effectiveness of these systems depends on the density and composition of the contaminants relative to the food product.

X-ray systems may struggle to detect contaminants that have a similar density to the food product itself. For example, low-density materials such as certain plastics, wood, or organic matter may not create a significant contrast in the X-ray image, making them difficult to identify. Additionally, very small contaminants or those embedded deep within the product may not be detected if they do not sufficiently disrupt the X-ray absorption pattern.

Some conveyor X-ray detection systems offer enhanced capabilities to detect physical contaminants. Some systems meet the challenge of detecting foreign objects anywhere in cans and bottles. Others are focused on bulk food inspection, or bags, boxes and flat packages. Food manufacturers should work with their product inspection partner to choose the best system for their particular application requirements. (See X-ray Inspection System Product Comparison Table.)

Summary

Packaged food inspection equipment and technologies are crucial to the safety of packaged food products and protecting the consumer. There are approximately 43,000 food and beverage processing establishments in the United States (according to the U.S. Department of Agriculture Economic Research Service 2022 statistics). Imagine the millions of food products that are being processed through those facilities. Then imagine how many packages containing foreign physical contaminants would reach your kitchen if there were no metal detectors or X-ray inspection systems being used.

It might make you lose your appetite.