Potato recall questions metal contamination prevention policy Recent high-profile product recalls highlight the question every food business should be asking when deciding to invest in metal detection inspection equipment - how much is your company’s reputation worth? Here, Sales Director Phil Brown, at award winning metal detector manufacturer Fortress Technology, discusses the impact and consequences.
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etal contamination is a food safety issue that can have an incendiary effect on a food business’s reputation, as recent events demonstrate. On 12 May, the Food Standards Agency announced that Sainsbury’s, Waitrose and Morrison’s were recalling products because of possible metal contamination. The culprit was a batch of potatoes from a single supplier that was used across a range of products, such as ready meals and potato salads. As well as generating the immediate expense of a mass product recall, the incident was widely reported - even hitting the national press. This kind of adverse publicity damages consumer trust and creates lost opportunities for all the businesses concerned. The supplier will certainly have had metal detection equipment in place, so how could this happen? The answer is that no system can entirely eliminate the risk of metal contamination. However, optimising metal detection systems can manage that risk more effectively and reduce it as far as is practical. Food operators should understand the factors that can leave them vulnerable, even if they already have metal detectors in place.
Material difference First, there’s the widespread use of stainless steels in the food industry. These are more difficult to detect than ferrous metals such as iron and steel or nonferrous metals such as copper or zinc. That’s because metal detectors work by spotting materials that create a magnetic or electrical disturbance as they pass through an electromagnetic field. Ferrous metals are both magnetic and good electrical conductors so they’re relatively easy to spot. Non-ferrous metals aren’t magnetic but they’re good conductors. Stainless steels are not magnetic and are also poor conductors, so they present an added challenge. In practice this means that in a sphere of stainless steel hidden in a dry product typically needs to be 50% larger than a ferrous sphere to generate a similar signal size. That disparity can rise up to 200 to 300% in wet products.
Shaping up
Size matters
Next there’s the question of orientation. The performance of metal detectors may be measured using spheres, but metal contamination may not be spherical. The most extreme example is a long, narrow wire, which may be easy to detect if it presents to the detector one way, but very tricky to spot if it arrives in a different orientation. It’s therefore important to optimise the performance of the detector to cope with the worst-case scenario. An improvement in sphere size from 3mm to 2.5mm may not sound like much but it can be the difference between success or failure when trying to spot an irregular fragment.
The performance of any metal detector improves as the aperture size shrinks, so users could optimise performance by using a number of smaller detectors positioned at critical control points throughout the process, rather than a single, big ‘catch-all’ detector at the end of the line. Of course, the downside to installing more metal detectors is extra cost.
Test and record
Businesses need to look at this from a risk assessment perspective. Think of it like fire insurance. No one intends to allow metal to contaminate their food products any more than they intend to burn down their factory, but that doesn’t stop them from investing in fire protection and insurance. In the same way, investing in metal detection reduces the risk of a company’s hard-won reputation for food safety going up in flames.
It’s also vital to check that any metal detection system will fail safe. So, for example, if a fault with the reject system means that a contaminant is detected but not rejected, the line should stop automatically until the situation is resolved. Both the detector performance and fail-safe capability should be tested regularly and full records kept to support traceability. Major retailers will typically have their own codes of practice that specify their testing and reporting requirements, but what happens in theory can be harder to implement in practice in a busy production environment – especially if the record keeping is manual.
Risk and reward When balancing up the risks and rewards of investing in optimised metal detectors systems, many users don’t perceive them as generating value for their business beyond the need to comply with customer demands, such as retailers’ codes of practice. However, shortterm thrift could be an expensive mistake in the longer term.
All Fortress systems come with a Never Obsolete pledge, which means that they have a guaranteed upgrade path for the duration of the equipment’s lifespan, however industry standards change over time. This ensures that food factories achieve an exceptional ROI, a low TCO (total cost of ownership) and benefit from high OEE (overall equipment effectiveness) – all of which reduces risk and improves reward gains.
Some metal detector equipment manufacturers – Fortress included – therefore integrate secure, automatic logging of all such information into their systems. This is something where a modest investment up front can lead to savings later on by narrowing the time window during which a problem can go undetected and reducing the amount of suspect products that must be discarded or Metal contaminants were found in a batch of potatoes used for ready meals recalled in case of an incident.
Automation Update - 9 June 2015