INDUSTRY FOCUS FOOD & BEVERAGE THE TRUTH ABOUT FALSE REJECTS
Reducing food waste in production is a priority, and false rejects from metal detectors can be a major contributing factor. Phil Brown, European sales director, Fortress Technology explains how the challenge is being met
F
actory food waste is a huge - and growing - issue for manufacturers, and one where choices about production equipment, including metal detection and other quality control, can have a significant impact on outcomes. According to the Waste and Resources
Action Programme (WRAP), surplus and waste food from UK manufacturing (including third-party logistics) was 2.4M tonnes in 2014 – ten times the volume from retail, and 4.2% of the country’s food production. Of this, some was redistributed to food banks and other beneficiaries, some was recycled as animal feed, but 1.7M tonnes remained as waste. It is indicative of the seriousness with
which these losses are now viewed that reductions in food waste play a prime role in the UK’s Courtauld 2025 Commitment. This voluntary scheme has as its first objective a 20% reduction of food & beverage (F&B) waste. It also aims to cut F&B-related greenhouse gas emissions by the same proportion and reduce the impacts of supply-chain water use. Signatories include the major grocery retailers and brand-owners such as Unilever, Nestlé and Coca-Cola. In addition to demonstrating corporate
social responsibility (CSR), companies able to reduce food waste will also see a positive impact on its bottom line. In the case of product inspection,
specific features of likely contaminants, the product, packaging, processing and supply chain may determine whether metal detection or x-ray is chosen for a particular point on the line. For example, x-ray technology cannot be applied to product in free-fall, such as snacks above a bagging machine. In other settings, x-ray may make better sense where it can add further quality control functions, such as checking fill levels or the completeness of a multi- component pack. Yet, in many cases, the decision will
26 MAY 2017 | PROCESS & CONTROL
depend on careful evaluation of the pluses and minuses of each technology. No supplier of either x-ray or metal detection can guarantee 100% infallibility. X-ray will always come at a higher
installation and lifetime cost than metal detection, so decisions should be based on an assessment of cost versus risk. The sensitivity of both types of system
will depend on a series of variables, from the potential size and composition of possible contaminants, to the liquid content and consistency of the product matrix.
Factory space and the radiation safety requirements of x-ray systems may be among other considerations influencing food manufacturers. Because the size, orientation and density of contaminants - among other variables - will affect detectability, both types of technology are set up and calibrated in order to err on the side of caution. But of course, manufacturers will want
to avoid excessive levels of false rejects, too. This is precisely where the competing demands of food safety and food waste overlap – and where the latest metal detection technology can help to cut waste while maintaining safety levels. False rejections, which occur when perfectly good product is identified as containing a contaminant, are most common on lines handling ‘wet’ items.
Developments in metal detection serve to demonstrate that food safety on the one hand and concerns about cost and wastage on the other do not necessarily pull the food industry in opposite directions. Technological improvements can help to contain costs, maximise space and reduce food waste
While this way of categorising products does include literally wet or moist consistencies, in anything from dairy products and dips to meat, it also refers to any food matrix containing high levels of salt or other mineral fortification. The common element is a strong ‘product effect’, which registers relatively high conductivity and magnetic permeability, mimicking the signal picked up from metal, and so making any distinction between the two hard to establish. Traditionally, stainless steel has been especially difficult to detect in wet products. Fortress Technology’s most recent
innovation in this area, the Interceptor metal detector, applies both high and low frequency ranges in order to isolate the product signal, and more readily identifies any contaminant signature beyond that. Trials with stainless steel in wet products have shown that Interceptor enables the pinpointing of contaminants as little as half the size of those detectable by the previous generation of equipment. Finally, false rejects can also result in
lower factory yield and repeated stoppages and consequent trouble- shooting. Reliable industry estimates put the cost per line of false rejects at up to £14,000, depending on the scale of the problem. High-speed, multi-line packing
operations have a number of options when it comes to contaminant detection. Manufacturers can channel multiple lanes through a single, large metal detection aperture. Or there is the option of positioning a separate metal detector over each lane. Both options have drawbacks. The Fortress solution, already installed
Surplus and waste food from UK manufacturing was 2.4m tonnes in 2014, ten times the volume from retail, and 4.2% of the country’s food production
on multi-line operations checking sachets of herbs & spices and snack pots, is a single metal detection system with multiple apertures for each lane and a single operator panel. Each aperture is sized as closely as possible to the product. On the sachet line, Fortress delivered a five-lane, ferrous-only multi-aperture detector. On five conveyors, end-users can save up to 50% of the space required by individual metal detectors, around 17% of the installation cost, and up to 65% of the total cost of ownership, taking into account reduced maintenance and parts requirements. The system automatically reduces food waste by 80%, even before the benefits of increased sensitivity are taken into account.
Fortress Technology
www.fortresstechnology.co.uk
/ PROCESS&CONTROL
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