Detection and inspection: spot the warning signs

By Rick Pendrous

- Last updated on GMT

Food and drink contamination presents a unique challenge for detection and inspection systems
Food and drink contamination presents a unique challenge for detection and inspection systems

Related tags: Technology & Automation

How does the industry improve its inspection procedures to reduce the high incidence of product recalls caused by physical contaminants?

Not a week goes by without the Food Standards Agency (FSA) issuing an alert about a food and drink product recall for one reason or another.

These are generally related to contamination of products with pathogens such salmonella or listeria. But they are often caused by contamination with physical objects such as metal – particularly difficult-to-detect stainless steel used in much food processing equipment – as well as plastic, glass, stone and bone, due to failures of control during manufacture.

On 12 September 2019, Struik Foods recalled Bunlimited Crispy Onions sold in Asda stores due to concerns that they might contain small pieces of metal. The following day, Booths recalled its Traditional Coleslaw because of fears it might contain pieces of white plastic.

Then, just two days later, Birds Eye recalled certain batch codes of 50 Chicken Nuggets with Golden Wholegrain as they might have contained small pieces of plastic. And, on 19 October, Bernard Matthews recalled 9 Turkey Dinosaurs because they might have contained small pieces of metal.

These recalls suggest that even with hazard analysis critical control point (HACCP) procedures in place, things can and do go wrong, causing disruption and cost to the companies involved – not to mention presenting potential risks to people. So, why are physical contaminants still getting through and what more can be done to prevent them?

Preventing recalls from happening

To demonstrate due diligence in their operations, companies are expected to implement procedures to prevent recalls happening. These include the use of equipment at CCPs, such as metal detectors and more expensive X-ray inspection systems for picking up non-metallic items such as bone and glass or for checking products packaged in aluminium foil.

Equipment suppliers agree a major problem lies in the incorrect use and calibration of equipment in such a way that it is not sensitive enough to detect the particles it should.

“There are two primary reasons for metal contamination escapes and, make no mistake, they are quite common,”​ says Bob Ries, lead product manager for metal detection and X-ray inspection at Thermo Fisher Scientific. “The first is the old technology detectors employed are not up to the task. The second is the detection system is being used incorrectly and/or may not be designed to be fail-safe.”

Checking that metal detection systems are fail-safe should form part of the agenda, suggests Phil Brown, managing director for Europe with inspection system specialist Fortress Technology.

If a fault with the reject system, for example, means that a contaminant is detected, but not rejected, the line should stop automatically until the situation is resolved, he says. Both the detector performance and fail-safe capability should be tested regularly, with results kept on record to support traceability.

Smart additional functionality

To help with the detection of contaminated products and ensure corrective measures are taken, Loma’s kit also includes smart additional functionality – or fail-safe features – that check its integrity.

Loma’s IQ4 metal detectors CW3 checkweighers, and X5 X-ray inspection equipment feature a Performance Validation System (PVS) that allows users to confirm inspection levels are correct. If equipment fails the PVS test, all products that passed through the machine since the last test will need to be retested or recalled for possible contaminants.

For the X-ray inspection equipment Eagle Product Inspection provides, Travis Ratcliff, service manager for North America, believes optimising equipment throughout its life is critical. “There’s a lot on the line when it comes to safety and quality, so inspection equipment has to run as optimally as possible,”​ he says.

Plastic contaminants present a particularly tricky problem since the small particle sizes likely to be present are not detectable by X-ray systems, explains Claus Borggaard from the Danish Technological Institute (DMRI).

Inline vision system

To address this issue, DMRI has developed an inline vision system called DynaCQ (Dynamic Check of Quality), capable of inspecting the surface of foods moving on a conveyor belt at speeds of up to 70 metres per minute. It is said to detect plastic particles as small as 2mm x 2mm.

However, when things do go wrong – as they inevitably will from time to time – speed of action in the instigation of recalls is essential. And this is where the effectiveness of companies’ traceability systems becomes imperative in quickly pinpointing the source of contamination. Increasingly, traceability systems are being linked to web-based software for wider access to the data captured.

“Although technology and automation play a part, food safety is a shared responsibility,​” says Fortress Technology’s Brown. “The rules and audits just help to add an additional layer of protection. By working together, food manufacturers, machinery suppliers, production staff, retailers and consumers can raise the bar on food safety.”

London-based Levantine, an edible nut and seed processor, which installed a new Fortress Stealth Gravity system on a bulk bagging line in 2019, emphasises the importance of calibration sensitivity. “We are British Retail Consortium-certified​,” says Levantine managing director David Danil. “As a part of that, we have HACCP assessments, with metal contaminant detection high up on the list of control points. Sensitivity levels are also hugely important.”

Without doubt, retailers are demanding greater assurance about supplier HACCP procedures, through their increasingly stringent codes of practice, and inspection equipment suppliers are responding to that need. For example, Thermo Fisher Scientific’s Sentinel multiscan metal detector can rapidly scan up to five frequencies at a time and has been approved for used on packaged products supplied to Marks & Spencer.

“Food manufacturers are increasingly adopting combination systems for more economical product inspection,”​ says Thermo Fisher Scientific’s Ries. “The Sentinel 3000 metal detector enables them to use advanced multi-frequency technology to keep consumers safe while optimising space. An integrated metal detector also provides superior value since the hardware is shared with the checkweigher.”

Why quality is part of the equation

BOXOUT - Key VERYX for Gummy Candies

Detection and inspection systems are not just required to ensure food safety, they are also an essential component of ensuring quality – from checkweighers to prevent below-weight packs or product ‘giveaway’, to optical sorting and level control in beverages and packaging seal integrity checks.

For example, German potato chip manufacturer Johanning Snack upgraded its high-capacity end-of-line packing lines using automated inline seal testers and DACS-G checkweighers from Ishida Europe for its Krosse Kerle potato chips. The equipment is used on 12 different pack formats, which have fill weights ranging from 20g to 200g. “Ishida was the only supplier to offer both seal testers and checkweighers in one package,” says André Wurz, technical manager at Johanning Snack.

The checkweighers incorporate the Ishida Data Capture System (IDCS II) web-based software that collects a wealth of data about each pack to provide valuable information and boost productivity. “IDCS II tells us what we need to know about line output​,” adds Wurz. “With IDCS II, we can log every packet of crisps and then pass these logs on to our customers.”

Elsewhere, Key Technology has introduced Veryx digital sorters for oil-coated, sugar-coated, yogurt-coated and vitamin-enhanced gummy confectionery, designed specifically to detect and remove foreign material and gummies with defects.

“Veryx’s unique sensor configuration not only allows for the most thorough all-sided surface inspection, but also offers patented Pixel Fusion for advanced detection​,” says Karel Van Velthoven, marketing manager at Key. “Our gummy candy customers with installed Veryx systems are experiencing a sort accuracy unseen until now.”

In future, systems are also likely to include elements of artificial intelligence (AI), according to Industrial Vision Systems director Earl Yardley. “Machine vision is used for final quality control in inspection, but new markets are opening up with the advent of 3D sensors and deep learning, utilising AI,” ​he says.

Related topics: Food Safety, Technical

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