Quality control (QC) is an integral part of any industrial-scale food manufacturing process, and is vital for ensuring that end products are free from contaminants. Inadequate QC can lead to unpredictable goods, damage a brand’s reputation and, at worst, prove detrimental to consumer health. Food safety is therefore understandably a high public health priority, and manufacturers must adhere to various complex guidelines in order to distribute their goods. Despite these regulations, many hazardous or unexpected items do still make it into the end products bought by consumers and can potentially enter food at any point in the supply chain. Understanding both the benefits and limitations of the different detection technologies currently available for food inspection applications can help to address this issue and plug the gaps in existing food safety strategies.

Know Your Onions—Which Platform Should You Use? 

It is imperative to incorporate a variety of suitable QC equipment—such as checkweighers, metal detectors and X-ray inspection systems—at multiple points in any food production line. These platforms ensure that each package has the correct mass and is screened for unwanted objects picked up during harvesting or deposited in the food by handling systems. The choice of inspection system, and where it is installed, depends on a variety of factors, such as the type of contaminants being identified, the product composition and the packaging material being filled. 

Metal detectors, for instance, can be installed anywhere along the production line and are amenable to a wide range of manufacturing conditions, offering protection from common metallic contaminants found in food workflows. In contrast, X-ray systems are generally only used at the infeed of raw materials and at the end of a production line. In combination with metal detectors, they provide a useful tool to bolster a company’s QC protocols, as they can detect non-metallic contaminants, such as glass, ceramics and stones. 

Both X-ray inspection systems and metal detectors can be used for identifying metal contaminants—including ferrous and non-ferrous metal, stainless steel, aluminum and wire—but it is worth noting that neither technique is suitable for non-conductive, low-density objects like wood, pits, hair or insects. X-rays generally detect contaminants of a higher density more effectively than those of a lower density and, for metal detectors, higher operating frequencies are more effective for picking up stainless steel foreign objects, whereas lower operating frequencies lead to better detection of ferrous contaminants. 

Food Safety—More Than Just a Piece Of Cake 

It is also important to consider potential “product effect”—signals caused by the intrinsic conductive and magnetic properties of the food item itself. This can sometimes be strong enough for the food to be flagged as a contaminant by metal detectors, especially in materials with high moisture and salt content, such as pickles and cheeses. X-ray inspection systems are therefore recommended when handling this type of food.

Packaging trends also continue to be a critical factor influencing the choice of detection technique and have been creating a greater demand for novel inspection solutions. For example, many food manufacturers are moving toward metalized films or foil-based packaging to improve the shelf life, visual appeal and cost efficiency of their products. In this instance X-ray inspection systems are recommended since this type of packaging creates too much background signal and reduces contaminant detection sensitivity, ultimately causing false rejects. This can lead to unnecessary downtime, product wastage and financial losses for the manufacturer. 

Last but not least, checking weights plays a vital role in ensuring that a company presents a consistent and high-quality product to the market. To this end, automatic checkweighers can be installed at the end of the manufacturing process, just before shipping. These devices have little impact on throughput speed, as modern checkweighers are now capable of scanning up to 350 packages per minute without sacrificing detection accuracy.    

QC That Takes the Biscuit

Giorgio Bonomi is the plant technical director at Forno Bonomi, an Italian company that became the first global distributor of savoiardi—also known as “ladyfinger” biscuits. Forno Bonomi started as a small artisan bakery just outside of Verona, and has since grown into an international business that employs around 200 people and exports its products to over 90 countries. Although the company has always valued quality control, as it expanded it had to put in more effort to maintain the standard of safety and quality expected by its customers. The bakery now has staff working around the clock to ensure its products adhere to stringent quality regulations and has implemented checkweighers, metal detectors and X-ray systems from Thermo Fisher Scientific at various points along the entire supply chain, from raw material to dough to packaged goods. Investing in the right tools is crucial for Forno Bonomi, as downtime affects manufacturing efficiencies, and issues result in loss of product, profit and brand reputation. 

Cooking Up New Technologies

There is currently no single QC solution for all food manufacturing processes, yet detection hardware and software is constantly being improved with the aim of identifying a greater range of contaminant types and sizes, promising greater food safety for customers. X-ray machines, checkweighers and metal detectors will undoubtedly play a central role in QC for the foreseeable future, but other technologies—such as infrared cameras that can identify leaks in packaging—are now starting to filter through the innovation cycle, and will soon find their place alongside these tools. More and more customers are also requesting the detection of low-density contaminants—such as stones, golf ball pieces, and plastic—further pushing the drive for new detection technologies. 

As QC methods continue to become more numerous and complex, manufacturers are increasingly acknowledging the importance of finding an experienced partner that provides both ongoing technical support and robust detection systems. High spec inspection systems, such as those produced by Thermo Fisher Scientific, are indispensable additions to food manufacturing sites as they work to keep consumers safe and uphold their brand reputations for decades to come.



U.S. Food and Drug Administration. Hazard Analysis Critical Control Point (HACCP). (2022).https://www.fda.gov/food/guidance-regulation-food-and-dietary-supplements/hazard-analysis-critical-control-point-haccp [Accessed 19 October 2022]