Food inspection and your bakery

Searching for contaminants like metal, plastic and glass, or food allergens like nuts and fruit? Bakers Journal explores metal dectectors, X-ray systems and what “traceability” means today.
Fortress Technology Ltd.
February 11, 2019
Written by Fortress Technology Ltd.
Food inspection and your bakery
Photo: Adobe Stock
Food companies have been subject to more frequent audits, with both Safe Quality Food (SQF) and the Food & Drug Administration (FDA) completing annual audits to the FDA’s Food Safety Modernization Act (FSMA) standards: Here's how to keep your business running safely.

1. From a trends perspective, what new developments do you see happening in inspection and detection equipment for the bakery/snack market in response to consumer demands? Are greater product variety and increasing consumer attention to quality and safety among key factors?


Over the last 12 months we have seen greater demand for faster, more-versatile inspection systems as manufacturers, particularly within the snacks industry, are facing increasing demand from retailers to provide products in different bag styles and sizes.

In order to run multiple products through metal detectors at higher speeds, there has been heightened interest in multi-lane metal detector systems. One of the twin-lane multi-aperture systems was installed by Borgesius bakery in Holland this year as the company wanted to be able to measure if there was a particular metal contaminant issue in the individual line. Because each aperture measures just 200 mm in height and 450 mm wide, the bread loaves pass right through the centre point of the metal detector. This means the inspection system can cope better with orientation and product effect. And because there’s a dedicated aperture for each lane, the range is more sensitive to smaller metal particles, detecting all metal types down 0.7 mm ferrous, 0.7 mm non-ferrous and 1.4 mm stainless steel.

Integration of equipment is commonplace is snack production environments. For instance, with baggers and checkweighers it is possible to have a single screen set up, linking all of the machinery together, resulting in a smaller footprint and simpler gathering of data.

There is also heightened interest in protecting high-value brands, and food safety is paramount. All bakeries and snack factories are different. If preparing items from scratch, we recommend checking incoming raw ingredients. Catching a metal contaminant in milled flour, for example, might cost a bakery business a few hundred dollars. Inspecting ingredients at this point will increase the likelihood of identifying a metal contaminant in its larger form. However, if inspection checks are left until after the mixing, baking and decoration process, an entire product batch could be contaminated with much smaller, potentially unidentifiable fragments. Here, the expense of wasted product, a recall and potential penalty fine may run into tens of thousands of pounds.  

2. What food safety requirements are impacting this area? Any recently enacted regulations?
Changes to food safety are being driven by U.S. legislation, and the continuing globalization of the food chain means harmonization of food safety standards will be inevitable. From January 2017, food companies have been subject to more frequent audits; Food safety guidelines issued by the British Retail Consortium (BRC) and the Global Food Safety Initiative (GFSI) are also largely converging towards FSMA.

The compliance deadline dates vary and are staggered based upon the size of a food business.

Notably, the new FSMA law impacts the longstanding Hazard Analysis and Critical Control Point (HACCP) principles, which have been superseded by Hazard Analysis and Risk-Based Preventive Controls (HARPC). The biggest difference in the HARPC standards is that they extend beyond Critical Control Points. Now, food processors are mandated to document all potential product risks, including naturally occurring hazards and anything that might intentionally or unintentionally get introduced to their facility.

3. Is there growing interest in detecting smaller metal contaminants and soft contaminations—materials other than metal, such as stone, glass, ceramic and detectable plastics? How about the inspection of incoming ingredients (e.g., nuts and dried fruit) in bakery/snack plants?

Some users naturally gravitate towards x-ray systems because they are perceived to be more versatile. It’s true that they have the ability to carry out further product inspection functions that are beyond the scope of metal detectors, such as spotting missing or broken products or checking the fill level. However, users need to be sure that any technical advantage will actually add value.

The choice in equipment is all based upon the most prevalent risk. Metal, predominantly stainless steel, is still likely to be the main contaminant in snacks processing and bakeries. This is in part due to high levels of automation in snack production plants, for example, sieving and mixing raw ingredients, slicing potatoes, and grinding flavourings, like spices.

In certain applications, it’s obvious which type of inspection technology to opt for, since only one of them can reliably detect the contaminants that pose the risk you’re trying to mitigate. However, it’s not always that straightforward. The two technologies will often succeed or fail depending on two different sets of criteria. Success with metal detectors tends to depend on the materials involved (the product, the packaging and the contamination), while x-ray detectors are more likely to be affected by other parameters such as the shape of product and the mode of transport through the unit, in addition to density differentials.

Putting this into context, x-ray systems cannot generally be used on free-falling products because of the inconsistent density within the falling product stream. This rules them out of many snack-bagging operations, such as VFFS lines. Meanwhile, if stone, glass, high-density plastics or bone poses the biggest risk, a metal detector will obviously be unable to spot them. It is, however, it’s worth noting that even an x-ray system will only be able to deliver reliable protection against these non-metallic contaminants under certain conditions.

4. Are x-ray inspection and metal detection complementary technologies? What are the strong points of each?
The upfront financial outlay of installing new equipment is naturally a major consideration, yet so too are on-going maintenance costs, which contribute to the total cost of ownership over your equipment’s life span.

Metal detectors are typically less expensive up front. What’s more, the price differential between metal detectors and x-ray systems increases incrementally according to the size of the aperture. So, for smaller units the difference in upfront cost may not be a deal breaker if investing in x-rays, but it may become insurmountable if a physically bigger system is required.

Energy consumption contributes to on-going costs. The difference here depends mainly on whether or not the x-ray system requires cooling systems, such as fans or air conditioners, which drive up energy consumption. In contrast, metal detectors are designed to be more robust in extreme environments, e.g. freezers, wet processing plants such as fish packing, and when dry ingredients are prevalent, such as flour in bakeries.

Another factor is the cost of spares and on-going maintenance. Although much more reliable than predecessors, generators and sensors still feature on new x-rays and remain consumable items. Spare part prices are typically quite high compared to a metal detector. In addition, support costs, such as paying for an independent Radiation Protection Advisor to conduct the HSE-required yearly safety inspections on x-rays, also need to be considered. With travel expenses, prices for this inspection can range from CA$1033 to CA$1722, per year.

Added up, the cost differences can be substantial. In the worst-case scenario, the total cost of ownership for an x-ray inspection system can be more than 100 times greater than that of a metal detector. In addition, potential safety and liability concerns mean that x-ray systems offer almost no resale value.

The sensitivity of both metal detectors and x-ray systems deteriorates as the size of the aperture increases. However, a number of other factors can impact on the sensitivity of the two technologies quite differently.

Metal detectors can identify all types of metal based on magnetic and conductive properties, while an x-ray system depends on density differentials. This means that an x-ray system may struggle to detect aluminium, including foil or metallised film.

On the other hand, foil packaging can present a challenge for metal detectors, which can only detect magnetic or ferrous metal contamination inside the package, while an x-ray system can detect all metals to some extent.  

Then there is the ‘orientation effect’ and the ‘product effect’ to consider. The orientation effect occurs if a contaminant is non-spherical, such as a piece of wire, in which case the ability to spot it may depend on the orientation it presents to the detector. In the case of x-rays, the presenting face must be equal to or greater in size than the base resolution of the detector diodes, which is analogous to the pixel resolution in a camera. Metal detectors are certainly not immune to the orientation effect, but they do not have this absolute cut-off.

In the case of an x-ray system, the product density and how uniform it is will both affect its sensitivity.

Footprint also needs to be considered. Limited space usually favours metal detection, as do applications where the speed of the product through the machine is very fast or very slow.

5. What are some challenges in designing equipment for bakery/snack plants?
Issues like product effect, machine footprint, product waste, reduced machine downtime, are among some of the main considerations.

6. What technological advances in inspection/detection do you see happening in the near future?
Traceability will continue to be important. As web-based technologies advance, many companies believe that more bakeries will embrace greater integration.

Another big development for snack manufacturers using gravity metal detectors is automatic testing. In many applications, testing the metal detector is made difficult due to access, machine position, product flow and environmental conditions. This is especially true in throat and gravity metal detectors connected to snack form, fill and seal systems that inspect loose or free-falling products, e.g. popcorn and crisps.

With manual testing it’s harder to get a consistent signal reading each time you run a test. That’s because you are relying on the test piece passing through the exact centre of the aperture. 


Fortress Technology Ltd. is a privately-owned Toronto-based metal detection company, that custom manufactures metal detectors to suit its customers’ needs. Dedicated to their Never Obsolete Commitment, new technology is developed to be backwards compatible and accessible without having to purchase an entirely new system. Fortress systems are used widely within a range of food industry sectors including bakery, ready meals, confectionery, and frozen foods. They offer a range of before-and-after sales service and support services, including product testing, training and preventative maintenance.

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