Streamlines processes while preventing product recalls and ensuring food quality

By Chengleng Ly, Application Center Manager, Eagle Product Inspection

X-ray technology is widely used for contaminant detection in food products. Scanning products to identify foreign objects ensures food safety and protects public health while helping manufacturers comply with regulatory standards and avoid costly recalls or claims. The technology can also improve food quality assurance programs. Read on to learn more about using x-ray systems to streamline production processes, prevent product recalls, and ensure the highest possible food quality.


How and why is x-ray technology used for product contaminant testing?

X-ray testing can be used to identify metal, glass, stone, and some hard plastics in packaged or unpackaged product, bulk, and raw foods. X-ray can penetrate packaging and detect contaminants that may be missed by human inspectors, ensuring a higher level of product safety and quality assurance and eliminating health hazards.

Both single and dual energy x-ray technology can be used for foreign body contamination detection. In a single-energy system, low-energy X-rays are directed onto a sensor or detector, and products pass through this beam before reaching the detector. The difference in absorption between the product and foreign bodies is measured to detect contaminants during X-ray inspection.

Dual-energy systems are preferred for products with diverse densities. These systems use two energy spectrums and a dual-layer detector to differentiate materials based on their chemical composition, allowing for more accurate detection in complex food products.


X-ray technology streamlines quality assurance, enhancing efficiency and accuracy

X-ray systems can also be used to perform quality control checks when paired with image analysis software. For example, Eagle Product Inspection's (Eagle) proprietary SimulTask™ PRO software can be used for mass measurement, object counting, assessment of package integrity, determination of fill levels, and identifying voids or missing products within packages. Here are just a few examples of these quality assessments:

Voids - identifies voids in burger patties and bread loaves.

Fill level inspection - prevents underfilling and overfilling with filler feedback for automated adjustment when processing canned foods jars or filling jelly donuts.

Mass measurement or weight checks - calculates mass to ensure accurate package weight for an individual product, each compartment of a multi-compartment package, or a box containing packaged products. Using communication by PLC to machines on line, fill and weight can be combined and signals can be sent to increase or decrease the fill. '

Package integrity - ensures no foreign contaminants are trapped in the seal of a package, metal clips are in the right place for a ground meat chubs, and desiccant packs are included in a beef jerky packages.
Component count - ensures count and inclusion of all required items, for example, confirms the correct number of meat balls are in a bag, all cookie packs are in a case, or the correct number of cookies is in a tray.

Product integrity - identifies and rejects damaged product before it reaches the consumer, for example, broken cheese slices or chocolate bars within a package.

Shape verification - ensures shape of cookie is round and not too oval, triangular, or square!

Damaged product - identifies a dented can that can be rejected before it reaches the end customer.


Comparison with other methods

In the past, food producers have used other contamination detection systems, including metal detectors, vision systems, and standard scale technology.

For example, metal detectors are excellent at detecting metal targets, but cannot be used for other contaminants like glass, ceramic, stone, aluminum, and very dense plastics. Vision systems can only inspect the surface of the product for objects of a different color. Standard scale technology takes weight measurement at a far lower speed than x-ray technology, which can measure weight accurately to within 1.5 to 2 percent of weight at high speeds on a processing line.


Use x-ray technology for the most thorough product inspection

X-ray technology provides a more thorough inspection of products than manual methods and can detect contaminants in food, regardless of their material composition or location within the product. It does not damage or alter the product, preserving the food or product's integrity while protecting public health and helping food producers avoid claims and recalls. That is why many food producers are beginning to replace both scales and metal detectors with x-ray technology.


X-ray product inspection benefits throughout the process

Removing contaminants at the beginning of the process helps protect additional processing equipment. Finding the contaminants before they are sliced up with the food and packaged helps the processor reduce product waste, which saves them money. Most, if not all, companies can benefit from x-ray product inspection for both detecting foreign contaminants as well as the additional quality checks. X-ray technology benefits accrue throughout the product processing train.

One of the best uses is at the beginning of the process during initial intake of raw materials. Take the example of French fries, where potatoes being received may get mixed in with foreign objects like rocks. There have even been cases where the potatoes were mixed up with golf balls; if cut into pieces the balls can damage machine blades. Using a standard x-ray, processors can perform a measurement of densities to locate both the golf balls and rocks before they are sliced up with the potatoes.


Developing the most cost-effective x-ray system

For x-ray technology to work properly, the system must be configured to the specific application, with information on product specifics, dimensions, throughputs, and customer's testing standards. This information is then used to determine which machine, generator, and detector is needed.
Here is a general overview of the process used by Eagle to tailor the x-ray system to the specific application:

1. Determine customer objectives - Does the process require looking for metals, glass, aluminum, porcelain, or dense plastics, and what are the size of contaminants they are looking for? A key factor is product density, which is important when determining the generator and detector configuration. To provide a competitive price point, the goal would be to provide the least expensive option that satisfies detection needs. For example, if the product is a protein mix and the producer is looking for metals of about 2.0 millimeters, the best system would be intermediate generators and lower to intermediate detectors because the contaminant is relatively large.

2. Conduct product testing - During the testing process, Eagle establishes a unique recipe for each product being tested. The process begins by passing clean product through the x-ray machine to train the system. At least 100 clean passes are then conducted to ensure zero false rejects. Contaminants are then introduced into the product, including metals, glass, and stone. These seeded products are run 30 times to assess the probability of detection. The system utilizes multiple algorithms simultaneously to determine the presence of contaminants within the product. Each one of the SimulTask™ PRO operators (contaminant finders) can be adjusted to increase the detection or make it less sensitive to reduce false rejects.

The testing process incorporates product variation tests to simulate inspection results for contaminant detection in different locations in the product or package. These variation tests consider multiple products because all may not be the same. For example, in jar and can applications, the crown or shape of the jar may be different. In that case, product testing would include placing the contaminant in different locations in the can or jar and running it through the machine. Testing includes running a minimum of 10 passes (and up to 100 passes) of the exact product.

3. Customize image analysis software - The image analysis software is critical to the right solution. For example, SimulTask™ PRO is used to craft customized recipes and includes auto-learn for contaminant detection and mass measurement. The software operates on a 16-bit system, enabling it to leverage 65,535 shades of gray, allowing it to find contaminants more easily. Many systems from other suppliers use only up to 256 shades of grayscale values, limiting image contrast capabilities.

4. Develop detection specifications - Detection specifications are presented as a range in the final report results, due to the controlled lab environment and the inability to account for all variables that may arise on a real production line. The range also considers slight variations in products from batch to batch, which cannot be fully captured during testing.

5. Report creation - Following the running of all the tests, applications experts create a report to explain the results and recommend the best system configuration.


See how the configuration and testing process works

The following example illustrates how the configuration and testing process works. The report highlighted below was prepared to determine the best x-ray technology option for a bulk vegetable producer. The customer was looking to identify a variety of contaminants, including stainless steel, glass, iron flakes, aluminum, stones, or rubber/belting. See samples in the accompanying graphic.

Because of the product characteristics, the recommended machine configuration used in the testing included an Eagle Pack 400 HC x-ray inspection system, EA420BE generator, and a Performance X-ray Technology PXT™ detector, which can detect contaminants and stone fragments that would otherwise go unseen to the naked eye.

Testing was conducted and product x-ray images noted the presence of a variety of contaminants, as shown in the graphic. The technology used proprietary software to enhance the contrast of foreign objects for better contaminant detection.

Customers receive a detailed summary and recommendations report with the results of contaminant and quality check testing. See the accompanying graphic for a sample of the report prepared for the bulk vegetable producer.

The report provides information on probability of detection (POD), which defines how likely a contaminant will be detected by the x-ray system. Customers then use this information to decide whether to purchase the x-ray equipment. In addition to the actual equipment, the selection includes consideration of the value the supplier brings to the table, especially after market support, software capabilities, and customer service.


X-ray product testing plays a crucial role in food safety

By leveraging x-ray technology, manufacturers can enhance food safety, comply with regulations, avoid costly recalls, and improve overall quality assurance programs. The ability of x-ray systems to detect various contaminants, coupled with advanced image analysis software, streamlines processes and enhances efficiency across the production line. As technology continues to evolve, x-ray inspection remains a cornerstone in maintaining high standards in the food industry.