Sarah Ketchin discusses why metal is still the biggest and most likely food contaminant and the best removal tactics
Metal remains the biggest and most likely contaminant risk within a food processing and packing plant today. In the raw ingredient phase, food is exposed to different processes from cutting meat, filleting fish, grinding spice or mixing dry and wet baking ingredients. Later down the line, you may be cutting larger quantities into more convenient single service portions or preparing ready-cut vegetables – again introducing a possible metal contaminant into the food supply chain. The rapid increase in automation uptake on processing lines has also had an effect. Using equipment to improve efficiencies and in some situations product costs, the need for sufficient checks and preventative maintenance practices becomes mandatory.
Risks on the line
Previously a team of manual operators would visually inspect wear of machine parts and wire mesh from sieves for example, yet with fewer manual workers on a line, the risk of metal contaminants increases. Installing a metal detection system is the first line of defence. However, it’s equally important to adopt a joined up approach to quality assurance, ensuring proper procedures are in place for controlling rejects, as well as a fool-proof process to determine the source of any contaminants picked up. Equipped with this information, appropriate actions can be taken to protect against costly product recalls and damage to brand reputation. Food manufacturers are under greater pressure to adhere to increasingly stringent levels of compliance and third party audits, whilst also having to contend with an ever-changing inspection market. With constant pressure on the bottom line, coupled with food safety legislation, the challenges continue.
Although today’s inspection and detection systems are good, it’s equally important to ensure it’s suited to the environment you are operating in. Do you, for example, require a certified wash-down system to meet retailer’s hygiene standards? Unsurprisingly, food processors can feel overwhelmed by the sheer breadth of choices and food safety initiatives they have to contend with. System suppliers have a duty to assist manufacturers in anticipating future requirements and staying ahead of the curve. It can be a bit of a minefield because, unfortunately, if a supplier doesn’t take the idea of modifications into consideration at the beginning, they can struggle to meet ongoing specification changes. For example, M&S recently changed its guidelines on metal detectors by adding an extra sensor on the reject line. This adds a physical restraint for suppliers because it means they need to accommodate for extra space on the end of a machine.
Basic tips
Whether you are looking to invest in a new metal detector or upgrading an existing system, there are some basic tips to bear in mind. Testing procedures and record keeping should not be overlooked. It’s advisable to run a detection and rejection of test samples on an hourly basis, at the beginning of a product run or at a shift change, and whenever any settings are updated or changed (always check the industry standards and auditing requirements for testing frequency and procedure). Ask about signal strength. Detector sensitivity is dependent on many factors: Aperture size, operating frequency, product speed and environment. Conductive wet products like fish are most limiting as they act like metal. Consider installing metal detectors at specific checkpoints along the manufacturing process. Leaving it until the end of the production line could result in high levels of false rejects and unnecessary disposal of good product and packaging.
Auto-assessments are especially useful when system access and positioning or environmental conditions hinder testing and you should investigate compatibility in case you want to upgrade any existing detectors in the future. Generally speaking, metal detectors are capable of phasing out and running products packaged in laminate foils with a good level of sensitivity. However, pure aluminium foil, i.e. an oven ready tray, may be too challenging and a ferrous in foil detector would be recommended. Taking into account the various operational risks, food processors are advised to seek impartial and professional advice. As technology advances, manufacturers can do a lot more calculations and processing of information by analysing the signals of a product as it goes through a metal detector. At Fortress Technology, for example, we are currently focusing on how customers can record, via USB information such as rejects and faults in addition to test records and results – all vital for audit compliance in one
