When the public purchases food off the supermarket shelf, they expect it, among other things, to be safe to consume. X-ray detection in food processing can be instrumental in improving product quality and food safety while reducing the risks of product recalls, reputational damage, and expensive lawsuits.
This article explores x-ray food inspection processes and capabilities and outlines what to look for in an x-ray system.
How Do X-Ray Inspection Machines Work?
In general, x-ray inspection machines perform three main functions:
- Create x-rays
- Detect contaminants via a sensor
- Process and report the data using high-speed computing
The process of x-ray inspection in food involves an x-ray beam directed toward the material or object being inspected; it interacts with the object and forms an image. The image is a representation of the package’s internal structure, and there will be variations in brightness, depending on the density of the objects being scanned.
X-ray food inspection technology allows for real-time inspection so that there can be continuous monitoring of objects as they move through the x-ray field.
How Are X-Rays Produced?
X-rays are a form of electromagnetic radiation in which the images are created by causing high-energy electrons to interact with matter. The image is taken by way of a glass tube that has two distinct parts:
- A cathode is a negatively charged electrode on one end of the x-ray tube.
- An anode is a positively charged electrode positioned on the other end of the tube. It is often made of tungsten, a material that can withstand high temperatures.
As the cathode is heated, the electrons move toward the anode. Upon contact, they interact to create x-ray images. It is the collision of the electrons that causes electrons with higher energy to fill “vacant” positions, creating the classic x-ray images that you see.
X-Ray Inspection Machine Recognition System
The difference in densities is what causes x-ray images to be recognizable as the bodies or objects that the rays pass through.
The way it works is that when the rays penetrate an object, energy becomes lost as the rays exert effort to pass through. These denser objects are contaminants that are recognized by a high-speed computer system that has the capability to perform thousands of scans per second, resulting in a darker shade of gray when a contaminant is detected.
From there, machines can analyze the data to form a conclusion. Human intervention may also be instrumental in performing advanced data analysis as well as performing essential visual recognition tasks.
For example, if an x-ray system is equipped with a visual recognition system, a human operator will monitor x-rays from a screen and make split-second decisions about unusually shaped items or defects present in the images. A human system is not perfect, however, as it requires training, and distraction or fatigue can affect performance.
An automated system can be more helpful in detecting contaminants by assigning an automatic density threshold to a product. If the density levels are exceeded, the system will initiate further steps to reject the item, whether that’s triggering an alarm or automatically rejecting the contaminated item off the production line. Other computer systems can also be used to account for products that could have natural density variations. This is referred to as automatic morphology processing.
How Do X-Ray Machines Eliminate Defects?
Rather than eliminating defects, x-ray machines are used more for detecting abnormalities in various food products and other materials, which is essential for ensuring food safety. Unlike other methods, x-rays are non-destructive detection methods because they don’t require opening or interfering with package contents.
Once a defect is detected, the system can alert another machine or human to intervene to remove or eliminate the defect.
X-Ray Inspection Detection Capability
As x-ray technology and systems have advanced, detection capabilities have also evolved. The exact materials that can be detected, however, will depend on the system you install and the characteristics of the material being inspected.
Further, for peak performance, it is recommended to conduct regular maintenance, calibration checks, and to strictly adhere to manufacturer specifications.
Most x-ray systems can detect the following:
- Metal, including stainless steel
- Some types of plastic, specifically higher-density plastics
X-ray systems are not limited to foreign body detection. The systems can also be used to check weight and fill levels or look for abnormalities in food products like flavor clumps or missing products.
X-Ray Inspection Machine Limitations
Despite the modern capabilities of x-ray food inspection systems, there are still limitations that make it impossible to detect certain objects.
The most notable limitations of x-ray inspection machines currently include the inability to detect the following materials at the same size as other, more dense contaminants (although the addition of A.I. is rapidly advancing these capabilities):
- Seeds and pits
- Paper and cardboard
- Cigarette butts
- Thin glass
- Low density plastic
Evaluating X-Ray Inspection for Your Application
As you compare various x-ray inspection systems for your specific application, there are several things to keep in mind that go beyond things like cost and customer service.
By thoroughly evaluating the considerations below, your business can make an informed decision about which x-ray scanning for food safety system will be most appropriate for your needs and operational objectives while meeting your regional regulatory requirements.
Are the Products Suitable?
First, it’s important to consider which types of products you intend to scan and whether those products are suitable for the system you’re evaluating.
The two most significant factors to evaluate here include:
- Size: As products pass through the machine via a belt mechanism, consider the size of the objects compared to that of the machine. They should fit adequately and not be oversized or under-sized.
- Method of product transport: This is a practical consideration that should be evaluated before making a commitment to a system. For example, liquids in jars can utilize jar inspection machines, while dry bulk items may be best suited for a belt machine.
Identify the Defects
You should also be clear on the types of defects you want the system to identify because there are variations in x-ray food inspection processes and capabilities between various manufacturers and models.
Keep in mind that x-ray systems are designed to detect density differences, so you need a machine that has the capability to detect the density differences for your particular type of food product. If you are running multiple products through the system, be sure to talk to the manufacturer about what food products you manufacture and what you need to detect.
What Is the Required Throughput?
In the business world, time is money, so you will also want to evaluate how quickly and how much of your product can move through the x-ray system. For example, will your items have to be inspected on a piecemeal basis, or will they be evaluated in bulk?
The required frequency of visual inspections and the methodology being used will influence how much throughput is necessary for your new x-ray system.
X-Ray System Safety
Safety should always be a top priority for employees, operators, and consumers. Be sure to inquire about the energy of the rays, whether x-rays are still being generated when power isn’t being applied to the tube head, and what other safety systems have been integrated.
The applications of x-rays in food inspection have evolved over the past decades, and many advanced systems are now available. At TDI Packsys, we create customized solutions to fit any business need in the food sector. Call us at (877) 834-6750 to learn more.