The most common inspection technologies used in potato processing are metal detectors because they can find very small metallic foreign objects (typically <2mm). Metal detectors are also reliable in difficult environments, such as those that are wet or dirty. Some advanced processors are also investing in X-ray technology which can be used to inspect finished (sealed) bags and detect non-metallic contaminants as well, such as rock and glass.

The Digital Option

To detect and remove foreign material, most potato processors use digital sorters to inspect bulk product on their processing lines as well as metal detectors and/or X-ray inspection systems on their packaging lines. Of course, advanced digital sorters such as VERYX® by Key Technology can do much more than eliminate foreign material – they also detect and remove product defects, and they can be equipped with Sort-to-Grade™ software to control potato strip lengths and/or Information Analytics software to collect, analyze and share big data across the processors enterprise.

Besides the detection of FM and defects and the control of strip length and minor defects with STG, advanced digital sorters can be equipped with Information Analytics software to offer another, massively powerful way to maximize operating efficiencies on potato processing lines. Information Analytics allows users to collect, analyze and share big data across their enterprise via an OPCUA-compliant infrastructure at the same time they sort product. Data about the sort process and about each and every object flowing through the sorter, whether the data is used to make sort decisions or not, is available to reveal patterns, trends and associations. This data can help a processor better manage incoming raw materials and optimize processes upstream and downstream of the sorter to achieve the next level in operational efficiency.

“VERYX is our best-selling digital sorter. Featuring sustainable all-sided surface inspection, unique multi-sensor Pixel Fusion™ and the highest resolution cameras and laser sensors on a digital sorter, VERYX removes more FM and the right amount of product defects to make grade while virtually eliminating false rejects to maximize yield. Smart features such as Sort-to-Grade (STG) software and recipe-driven operation ease use and help VERYX operate at peak performance. STG enables VERYX to adapt to normal changes in the product and consistently makes grade without operator intervention to maximize product quality and yield simultaneously. Recipe-driven operation enables potato processors with different cut sizes and shapes to save sort settings to memory for quick recall. Recipes simplify use and ensure repeatable results so product quality is guaranteed, regardless of personnel changes and across multiple lines and locations,” says Karel Van Velthoven, Advanced Inspection Systems Product marketing manager at Key Technology.

After Detection

Once a digital sorter identifies a piece of FM or a defective product, it actuates its ejection system to separate the bad from the good. Most sorters use air valves that open to target FM and defects while in-air, applying enough air pressure to alter the object’s trajectory to land in the reject stream. Key’s representative says that intelligent sorters can actuate one or more valves to reject each object, using contour-based or centroid-based calculations to target precise locations on the object to maximize FM and defect removal and minimize false rejects. Sorters equipped with three-way sorting can be configured to utilize a ‘reject’ stream that leads to waste and an ‘accept’ stream that leads to further processing as well as a third stream for product that’s below grade or needs rework. To recover good product from potato strips with defects, processors rely on Key’s ADR automatic defect removal systems. As the only vision inspection system on the market designed specifically to cut out defects from potato strips, ADR recovers French fries with defects and turns them into ‘good’ product, directly increasing yield.

As for some of the most commonly encountered foreign materials, these include shards of rock and glass fragments, as well as scraps of metal, can all be introduced during production. That is why X-ray is emerging as a growing standard of inspection because it is capable of detecting those non-metallic objects, according to specialists from Thermo Fisher Scientific.

Thermo Fisher Scientific Equipment

“All of Thermo Fisher Scientific’s detection systems incorporate automatic rejection systems. This is a critical process control that some production guidelines mandate. For food safety, it is recommended that all rejected material be scrapped,” says Bob Ries, lead product manager, X-Ray and Metal Detection, Thermo Fisher Scientific. “Currently, Thermo Scientific APEX metal detectors are most common, but many of our customers are starting to migrate to our advanced Thermo Scientific Sentinel Multiscan metal detectors. This system uses multifrequency technology that enables it to scan up to five user-selected frequencies at a time, effectively acting as five metal detectors in one to drastically improve performance, sensitivity and probability of detection. Combination systems are also a growing trend among processors because they provide the capabilities of two different systems in one machine, resulting in a smaller footprint. We recently announced a new combination system that combines our Sentinel 3000 multiscan metal detector with our Thermo Scientific VersaWeigh and Versa GP checkweighers,” Ries adds.

Optical Improvements

Optical grading of potatoes is the new frontier, according to technologists from equipment manufacturer Sorma, as it enables packers to offer only a product with constant quality: uniform and free from internal and external defects. It reduces food waste while simultaneously increasing consumer satisfaction. Specifically, InstanDEF is the newest software version launched by the company, which allows to define the quality of the individual potato with greater precision. Through complex multi-spectrum interfacing algorithms, developed by the Sorma Iberica R&D centre, the number of images analyzed for each produce has been doubled, delivering more precise detection of both external and internal defects. On completion of the process, the product that reaches the shelves will be in the ideal conditions to ensure high sell-out rates.

Sorma Equipment

“First of all, it is essential that all the production line machines are integrated and capable of ensuring a fast, continuous product flow, within which the product is sized and weighed at every phase of the process, in order to maximize the performance of the entire line. Logistically, we suggest that our client companies equip themselves with a warehouse capable of storing a higher production capacity than necessary: when working with seasonal products, unforeseen delays are the order of the day. Therefore, when this happens the delay can be recuperated thanks to this preventive strategy, thus enabling the allocation of more machines working in parallel to catch up on production,” say Sorma representatives.

The Sanitation Angle

All companies who provided input for this material agree that equipment hygiene is important throughout potato processing plants, with the most concern after the last ‘kill step,’ such as blanching, frying or freezing, where bacterial contamination could have the most disastrous impact. Beyond equipment hygiene, most digital sorters have an added sanitation challenge that comes from product splatter obstructing sensor windows and degrading light sources and backgrounds, all of which hurt the sorter’s performance.

“Overcoming this challenge was a driving force in the design of VERYX. With the needs of potato processors top of mind, we created a totally new mechanical architecture with sensors, light sources and backgrounds located away from product splatter. This radical design helps keep these surfaces clean, enabling us to configure VERYX to achieve full-surface inspection sustainably throughout the longest production cycles in the most demanding, high-volume environments using entirely in-air top and bottom viewing. Sanitation was one of the biggest problems that processors had with traditional sorters, and solving that drove us to design VERYX,” concludes Van Velthoven.