By Robert Rogers, senior food and safety advisor at METTLER TOLEDO Product Inspection Group
New packaging formats are booming. Demographic change, changing consumer shopping and consumption habits as well as changing demands from retailers are driving innovation in food packaging. An increasing number of single-person and smaller households and the trend away from the big shopping trip towards more frequent, spontaneous shopping trips are all driving increasing demand for smaller packaging units. Consumers also want greater convenience, with food that is easy to prepare, and they want food manufacturers to be environmentally conscious by using recyclable packaging materials and functional packaging that contribute to a reduction in waste.
At the same time, the retail sector’s demands for practical, appealing food packaging go far beyond the traditional function of protecting the product. Retailers also want good barrier properties, resistance to damage during shipping and taste neutrality. They demand convenience, with shelf-ready packaging that is stable, stackable and available in multiple sizes to serve the widest range of buyers across all channels. Retailers also require the low package weight and minimal material use to minimize shipping cost, waste and potential environmental impact.
Increasing Demands on Foreign Body
Inspection This wave of new and more diverse types of packaging and materials, from a dramatically increased use of flexible packaging to new barrier packaging materials, presents packagers with a range of new challenges. They introduce more complexity into detecting potential physical contaminants on production and packaging lines. Food manufacturers today must be sure that their product inspection systems can adapt to a change in packaging as quickly as possible and with a high degree of automation using high-performance software and intuitive user interfaces to keep changeover times short and overall equipment efficiency high.
This is leading, in turn, to a wave of inspection systems designed to meet the new challenges. Newer highly automated inspection solutions, providing quick access to stored product profiles in databases and simple setup procedures for new product targets, minimize the risk of operating errors. Inspection systems featuring improved interactive, touchscreen-based HMI user interfaces are better able to guide operators efficiently through more demanding setup, changeover and operating processes.
Optimizing Foreign Body Detection
Factors such as the size and location of a contaminant, the speed of the production line, the product packaging material and the difference in density between the contaminant and the product all influence the sensitivity and performance of metal detection devices and X-ray inspection systems. The ability to detect contaminants at an early stage of processing and production is important, before value has been added through processing and packaging, to deliver the most cost-effective result. In many production processes, raw materials supplied in liquid, paste or slurry format and pumped through pipework systems before being mixed and blended are more homogeneous and easier to inspect than the processed food product. The contaminants in such incoming materials also tend to be larger and easier to detect. Early detection and removal of foreign bodies protects the production equipment downstream from possible damage by these larger contaminants during further processing while product loss and food waste are also minimized.
Choosing a system for inspection further downstream on the production line requires more expert knowledge. Inspecting for aluminum contaminants in nonmetal packaging, for example, is done most effectively with a metal detector. Aluminum is a lightweight metal and a good electrical conductor but its radiographic absorption is low compared to other metals such as ferrous and stainless steel. This causes a reduction in the sensitivity on an X-ray inspection system. In contrast, due to its good conduction properties, aluminum can easily be detected at smaller sizes using metal detection which makes it the better solution. By contrast, when inspecting for metal contaminants in products packaged in aluminum foil, metal detectors struggle to identify the contaminants separately from the packaging. But because aluminum has a negligible impact on X-ray detection levels, an X-ray inspection system can see straight through a low-density foil to immediately identify the metal contaminants within, producing a better solution.
Particular Challenges Presented by New Packaging Materials and Formats
Flexible packaging such as stand-up pouches, as well as glass jars and weight-optimized cans with vaulted bottoms, bring with them a hidden challenge – blind spots. Contaminants can become lodged in the sharp angles of such packaging, making detection more difficult. A particular challenge is presented by glass-inglass contamination–for example, where the glass at the rim of the jar has broken off, fallen into the container and, in the worst-case scenario, became lodged in the rim of the jar’s vaulted bottom. In general, recognizing contaminants at the base and sides, particularly in glass containers and tin cans, presents major technical demands for inspection technology. But newer X-ray solutions that inspect every product from multiple angles by using multiple X-ray beams and comparing the two images, optimize the chance of successful detection. Further technological developments also make identifying very small contaminants quicker and more reliable.
These newer demands on product inspection capabilities will continue to arise as brand owners introduce more diverse packaging types. In many cases, those companies that have purchased newer metal detection or X-ray inspection systems may find that technology can adapt to the new challenges and continue to provide the optimum solution for reliable foreign object detection, but they will need to validate that capability. Those with older generation systems should seek advice from professional product inspection experts and work with them to conduct product inspection tests to determine the most suitable technology for their specific needs.
About the Author
Robert Rogers, senior food and safety advisor at METTLER TOLEDO Product Inspection Group, serves as a subject matter expert to various regulatory and industry organizations, such as the Food and Drug Administration (FDA), Grocery Manufacturers Association (GMA) and the Packaging Machinery Manufacturers Institute (PMMI) and writes articles and blogs about this critical industry issue. He can be contacted directly at email@example.com.