Inspecting for contaminants: nuts about snack satisfaction

To maintain freshness, metallised polypropylene is the snack industry's standard for packaging. For many manufacturers that deploy metal detectors, ferrous in-foil detectors can be used. Settings can also be adjusted, so foil laminated packaging is rarely an issue for today's advanced metal detectors. There's also the alternative of passing product through a metal detection systems before the packaging process commences.

Contrary to popular belief, metal detection remains a modern-day option. As with any technology, metal detection hardware and software are evolving all the time and these developments keep pace with evolving retailer requirements.

Typically, snack manufacturers will have more than one metal detector between the beginning and end of the production and packing process, corresponding to identified Critical Control Points (CCPs). Many will install a system as close as possible to the end of line after primary packaging, typically bagging with snacks. If that is not feasible, just before the bagging stage is also effective. In these situations, loose product such as chips or crisps can be channelled through a vertical "throat' detector.

It is also likely that manufacturers will want to check incoming ingredients before they reach the processing stage. This might be advisable for a number of reasons. Firstly, snack producers will want to identify the source of any metal contamination, which may of course include raw materials. Secondly, the sensitivity achieved at this stage may be higher than with finished or packaged product. This may come down to the aperture of the metal detector or the relative sensitivity obtained with unprocessed and processed ingredients.

So why choose metal detection rather than X-ray? The answer will depend on the application. X-ray remains far more expensive, both in terms of capital cost and running costs. Depending on the application size and complexity, expect to pay in the region of 35,000 to 40,000 to install X-ray, compared with 4000 to 18,000 for metal detection.

Integrating a metal detector into a snack processing or packing line is relatively straightforward. Consideration needs to be given to "product effect', although with today's technology this "phasing' or calibration is an automatic process.

Stringent protocols and standards

In recent years, retailers have become more risk-averse when it comes to food safety and quality, increasingly imposing their own stringent protocols and standards on suppliers. As well as ensuring that the required form of inspection is in place, to the necessary specification, the retailer "safety net' will also often include assurances about regular system checks to ensure that all QA systems - including metal detection - are functioning correctly.

As one might expect, the sensitivity of metal detector systems keeps improving which enables snack processors to detect ever-smaller metal contaminants. Fortress Technology's FM software improves performance in some applications by 40 per cent. This is down to an algorithm that factors in both time and amplitude with every detection signal.

Some retailers may pressurise suppliers to invest in X-ray contaminant detection. Being able to demonstrate the reliability and improved sensitivity of metal detectors installed with FM software, for example, may strengthen the case for snack suppliers.

Before selecting your inspection equipment, snack manufacturers should carefully research potential sources of contamination. Naturally, if your potential contamination is all, or mostly, metal based, it makes sense to consider metal detection as a first option. If the contaminate risks are wider ranging, or predominantly non-metal by nature, it may be worth examining the benefits of X-ray in more detail. One thing worth considering is even the latest X-ray systems are not foolproof. Some have trouble detecting the smaller particles and low-density metals - such as aluminium - that metal detectors will pick up as a matter of course. In fact, the reliability of X-ray in identifying a range of potential contaminants has been questioned over the years.

Ultimately, manufacturers worry when metal contaminants are detected. Understandably they may also worry when they are not. Improved automatic testing tackles these concerns. For example, Fortress Technology's HALO system is an external test designed to supplement, but not replace, manual testing on throat, pipeline and gravity metal detectors used for loose or free-falling snack products such as crisps and nuts. HALO generates a signal identical to that of particles of different sizes and metals, so multiple test levels can be checked easily. It is also a more objective and repeatable test than manual or most other automatic alternatives.

When it comes to brand reputation, consumer satisfaction is everything and contaminant detection is critical for maintaining product trust. With the future of snacks looking strong and more and more healthier variations entering the market, now's the time to explore your inspection options and ensure your quality product gets the shelf space it rightly deserves.

For more information about systems for inspecting for contaminants go to www.fortresstechnology.co.uk.