Potato Review

www.potatoreview.com POTATO REVIEW JULY/AUGUST 2021 47 CONTAMINATION/INSPECTION change the frequency of operation to minimise the e ect of the product. But there’s a trade-o . Doing this can impact the ability to nd di erent metals. Dropping the frequency tends to enhance ferrous metal detection. Yet this limits performance when it comes to non-ferrous metals, since the lower end of the frequency is more responsive to magnetic e ects of the contamination. By the same token, the reverse happens when the frequency is taken higher – it starts to limit the ferrous detection capability but enhances the non-ferrous detection. Simultaneous frequency is the most reliable way to remove product e ect without compromising the sensitivity of a metal detector, Phil said. For example, Fortress uses ARM microprocessors to adapt to these changing product characteristics. is processing technology powers the interceptor, enabling it to run real-time analysis of the low-frequency and a high-frequency signals in parallel. By the same virtue, as products travel through processing facilities, environmental conditions change. Factory temperatures rise and dip. While warm products can cause moisture to gradually evaporate, frozen food can thaw. A change of just 5°C is enough to a ect the product characteristics and disrupt product signals. Special tools can be included on metal detectors that track long term changes within wet products, adapting and syncing to new characteristics. ey accommodate gradual change in batches without compromising metal detector sensitivity. “Even products that look di erent to the metal detector won’t be rejected,” said Phil. Phil cites packaging as another common example where such technology can help. Whereas inert plastic presents minimal signal, metallised lms and the application of print can vary between rolls. “Just a small change can present itself as a big signal to a sensitive metal detector,” said Phil. Although once deemed a major challenge for metal detectors, today’s advanced simultaneous frequency systems are much more reliable inspecting pre- wrapped products. For crops like potatoes, x-ray inspection systems can play a critical complementary role, he said. “Often, a system like Sparc’s Apollo bridges the gap in inspection capabilities and ensures the most robust screening process for contaminants, ensuring absolute quality of the end product,” said Phil. Cause and e ect e presence of xenobiotic compounds is routinely monitored and tightly controlled by regulatory bodies. However, farming practices, regional soil structures and natural crop cycles, although rare, can also in uence the nutrient content of fresh produce. Inspecting potatoes grown, for example, in iron rich soils might require a slightly di erent calibration setting to those grown the other side of the country. Phil recalled the impact of a potato product tampering scandal a few years ago in North America. He said: “Several years ago, steel needles and other sharp metal objects were detected in Prince Edward Island (PEI) potatoes at processing plants and in bags sold throughout Atlantic Canada. One potato farmer, keen to reassure its extensive customer base invested in three robust industrial- sized metal detectors, each inspecting 140,000 pounds of potatoes every hour.” Phil highlights that features like BSH rugged casing helps to provide better stability and metal detector performance in harsh environments where rolling potatoes can bang into things. Further down the line, a metal detector that can run multiple frequencies simultaneously, such as the Fortress Interceptor, is ideal as it can accurately inspect a variety of conductivities, for example a ready meal topped with mashed potato at the same time. Features like single pass product learning and automatic calibration also help, as operatives are not constantly resetting the machine to accommodate di erent product e ect, shapes, sizes and orientation. Never underestimate the in uence of environmental factors, advises Phil. “When it comes to food safety, there’s always a cause and a consequence. Having deep-rooted experience about how di erent food products behave and change, the conditions that cause these reactions, and the relearning limits of inspection equipment is critical.” “Several years ago, steel needles and other sharp metal objects were detected in Prince Edward Island (PEI) potatoes at processing plants and in bags sold throughout Atlantic Canada.” Understanding the chemistry behind contamination is crucial to getting the best from machine and product. Density, water concentration, storage temperatures, heat, thawing and even seasonal and soil variations, are among the many factors that could a ect the performance of food inspection machines dealing with potatoes.