Finding and removing metals during food production is of the utmost importance. Production lines present many opportunities for metal to work its way into products, which is why manufacturers implement detection systems to catch potential contaminants. However, accurately identifying metal in foods before they leave the assembly line is more challenging for certain products than others.
Specifically, the challenges in metal detection for packaged foods add a layer of concern for many manufacturers. Using the right equipment and best practices can help them overcome this issue and deliver safe, contaminant-free food products to consumers.
Common Challenges in Food Metal Detection
Metal is the most prevalent contaminant in food manufacturing. Facilities use countless metal products during manufacturing, from mixing tools to maintenance equipment, which generates a significant risk of particles or pieces becoming embedded in the food products.
Responsible manufacturers must use metal detectors to identify such contaminants before their products make it out of the facility. Yet, several challenges in metal detection for packaged foods make reliable detection difficult.
Product Effect
Certain food products have a high “product effect,” meaning their conductive properties mimic those of a foreign object, falsely triggering the metal detection system. This can make it challenging for systems to recognize when products actually contain contaminants rather than normal characteristics that set off a false alarm.
Several characteristics in food products can set off metal detectors, including:
- Excessive moisture
- High salt content
- Conductivity of packaging or ingredients
Manufacturers should examine all false alarms rather than overlook potential contaminants, but this adds significant time to the production process.
How Packaging and Equipment Interfere
The packaging and equipment used within food production can also trigger metal detectors. Many food products, including twist ties, aluminum foil, and cans, use metal in their packaging.
Products that contain metal in their packaging will virtually always trigger metal detectors, but they can also put nearby food products at risk. They may interfere with the detector’s electromagnetic field, causing it to identify false positives in other foods.
Varying Sensitivities to Different Types of Metal
Traditional metal detectors can identify some types of metal more reliably than others. These systems need the proper sensitivity calibration to pick up on all metal types.
Ferrous metals contain iron and are magnetic. These are much easier to find with industrial metal detectors than non-ferrous ones, such as aluminum, lead, copper, and nickel.
Metal detectors primarily use magnetic properties to identify metal contaminants. Unfortunately, there is a much larger number of non-ferrous metals than ferrous ones. Setting sensitivity thresholds to pick up on these non-iron-containing materials can make detectors more precise, but also opens them up to more false rejections.
The Effect of Orientation and Size
The orientation effect poses another significant challenge in metal detection for packaged foods. This refers to how the orientation of a metal contaminant affects the detector’s ability to identify it.
Often, non-spherical contaminants pass through metal detectors unnoticed. Similarly, it is easier for metal wires to be detected when they pass through the conveyor belt sideways or upright instead of in the same direction as the belt.
Overcoming this barrier requires operators to reduce the aperture size on the metal detection system. This makes the machine more sensitive, which can lead to more false alarms.
Operational and Human Factors That Affect Metal Detection
While modern metal detector systems are fairly autonomous, they do require occasional maintenance and recalibration. Workers also need to know how to operate them correctly. They may need to adjust the aperture or sensitivity for certain products or know how to manually override false rejections.
As a result, user error can affect the efficacy of these systems. If a company fails to maintain its detectors adequately, it could miss contamination events.
Distinct Challenges Certain Food Categories Face
Metal detectors have several limitations when it comes to identifying contaminants in food products. However, certain types of products also pose a higher risk of missed detection. These are the challenges manufacturers encounter with detecting metal in specific food categories.
Detecting Metal in Dairy Products
Dairy products like cheese have high moisture and salt content, strengthening their product effect. These qualities increase a product’s conductivity, interfering with the electromagnetic field used in metal detection systems.
Yogurt, cheese, milk, and other dairy products often move through the assembly line at cold temperatures. They may even go through the packaging process while frozen. However, changes in temperature can also impact the sensitivity of the metal detection system. This is especially problematic when the first few products in a batch are colder than the latter few, often increasing in moisture levels as the end of the batch starts to thaw.
Some dairy products use metallic packaging, such as the foil lids on yogurt cups. The texture and consistency of many products in this category can also create calibration challenges for detection systems. Dairy tends to be very dense, and some products, such as cottage cheese or yogurt cups with fruit on the bottom, do not have a consistent texture throughout.
Finding Metal Contaminants in Meat Products
Meat products pose many of the same challenges in metal detection as dairy. These items tend to have high salt levels, and they often experience variability in moisture levels throughout production. When meat starts to thaw as it moves down the packaging line, a metal detector will read it differently than a completely frozen product.
Meat processing aids can also interfere with the inspection system. Manufacturers often use metal clips and hooks to hold meat products during various stages of production. These parts set off the detectors, causing workers to potentially overlook actual contaminants.
Because meat products come in many different formats, ranging from ground meat to bone-in cuts, manufacturers must use multi-frequency detection systems that can adapt to the different textures, consistencies, and sizes of their products.
Identifying Metal in Baked Goods
While baked goods may not initially seem like a significant cause for concern in metal detection, their properties can also disrupt the inspection process and lead to false rejections.
Freshly baked breads and pastries are often warm, which can decrease the metal detector’s sensitivity. These goods also tend to have a higher moisture content, especially while warm. Metal contaminants may pass through unnoticed as a result of these qualities.
Loaves of bread, flaky pastries, and other baked goods often vary in their internal structures and densities. They may have air pockets or crusts that are of different densities than the rest of the product. This can make it challenging for a metal detector to conduct a consistent scan for discrepancies in the baked goods.
Even more challenges arise when manufacturers fortify their bread products with iron. This ferrous metal is easily detected by even basic metal detectors, leading to false alarms.
Finally, breads, cakes, muffins, and similar items often use metal packaging, such as twist ties or foil trays.
How To Mitigate Challenges in Metal Detection for Packaged Foods
Accurately detecting metal contaminants in packaged foods is not without difficulties. However, manufacturers need to be able to overcome these challenges to ensure the safety and compliance of their food products. Thankfully, they can follow several best practices to overcome common challenges in metal detection for packaged foods.
Using Advanced Detector Technologies
While basic metal detectors may struggle to perform their duties when variations in product density, temperature, and orientation are present, modern technologies overcome some of these challenges. More manufacturers have begun switching to multi-frequency or multi-scan detectors that reduce product effect.
These machines leverage improved signal processing and automatic phase adjustment features. This allows the detector to adapt to variations in the product’s inherent characteristics while identifying discrepancies that may indicate metal contamination.
Adjusting Manufacturing Processes
Manufacturers can also make strategic adjustments to their products to aid the detector’s abilities. For example, problems sometimes arise when frozen products begin to thaw as they move along the packaging line. The products at the beginning of the line may still be frozen, but those near the end may have begun to thaw, leading to condensation that triggers the inspection system.
While workers can work in smaller batches to prevent thawing, there will always be variations in temperature in any food production line. Adding more advanced modern scanning systems can help mitigate this issue.
Adjusting the timing of the metal inspections may also improve efficacy. For example, products that contain metal packaging should go through detectors before they start the packaging process. Meat products that use metal hooks or clips should undergo metal detection after processing.
Prioritizing Frequent Calibration and Maintenance
Even advanced metal detectors require regular maintenance and calibration to continue performing at the highest level. Manufacturers should enact strict protocols for when and how workers should calibrate the equipment. This may involve using test pieces for each batch of products to set the sensitivity to the right level.
The equipment manufacturer should give maintenance recommendations and schedules, and companies must adhere to these strictly. They should also ensure that all new operators receive extensive training on how to use the detection equipment correctly. This can prevent user error from impacting food safety.
Using Other Inspection Methods As Backup
Finally, manufacturers should use other inspection methods alongside metal detectors to catch overlooked contaminants. For example, many companies use x-ray inspection systems to examine products with metallic packaging. These systems check for visual or physical inconsistencies in the product that could indicate the presence of a contaminant.
Companies can use magnetic separators to simplify this process. These systems contain magnetic pulleys that attract ferrous materials, lifting these items out of the product stream. These materials can then go through a separate inspection process with the use of x-rays or other machines.
Future Trends and Innovations To Explore
Over time, many of the current challenges in metal detection for packaged foods may become obsolete due to new innovations and technologies. For example, AI-assisted detection could automatically override false alarms and other common errors that arise. Metal detectors may also use enhanced sensor arrays to better distinguish between metal and other conductive characteristics, like moisture content and temperature.
Companies can also integrate their current detectors with quality control systems, like data analytics and real-time monitoring, that catch and mitigate errors. This may become even more important as evolving regulatory standards require manufacturers to meet stricter regulations for metal contamination.
Source High-Performance Metal Detectors From TDI Packsys
TDI Packsys is a leading provider of quality metal detection systems for the pharmaceutical and food industries. We offer diverse equipment styles to ensure the best fit for your assembly line. Several of our systems are also dual-purpose, such as our metal detector and checkweigher combination systems.
Let us work with your business to overcome common challenges in metal detection for packaged foods. Call us today at 877-834-6750 to speak with a representative and learn more about our inspection systems.
