Thursday, 21 September 2017


Digital sorting has recently experienced a step change. This disruptive new technology, which has been in commercial use at potato processing facilities around the world for more than a year, offers novel capabilities and delivers new standards of performance. What’s different? Everything: from the sorter’s mechanical architecture to its sensors, software, ejection system, user interface (UI) and more, both incremental and disruptive changes have been brought to the market. In this article, I’ll describe what’s different and present the benefits that these features bring to processors of potato strips and specialty products.  

by Marco Azzaretti, advanced inspection systems product manager at Key Technology 
The needs of potato processors push technology advancements. There is nothing new to these driving forces. Processors seek improvements in product quality, increases in yield, greater automation to minimize labor, enhanced equipment ease of use to reduce training requirements, superior sanitation, simplified maintenance, greater operational efficiencies and lower cost of ownership. What’s also different is how today’s advanced digital sorters are doing more to better satisfy these objectives.

All-sided Surface Inspection

For years, potato strip processors have been demanding the all-sided surface inspection of each item in their product stream. But the production challenges in sustainably achieving this have seriously hindered its success – until now.

Thoroughly inspecting all six sides of a potato strip enables every foreign material (FM) and defect to be detected and removed. Orthogonally positioning cameras and laser sensors allows for top and bottom viewing, while positioning cameras in an off-axis configuration achieves all-sided viewing of each object. The problem with legacy sorters is that bottom-mounted sensors, when present, are located, such that they are subject to product splatter, as wet potato products splash their starchy residue onto the sensor windows, which gradually inhibits viewing until the windows are cleaned. In high-volume production environments, where sanitation routines are scheduled two weeks or more apart, such extended run times essentially render the bottom-mounted sensors useless.

Now, a giant leap forward in full-surface inspection functionality is here. This dramatic step change is possible, thanks to new mechanical architecture on belt-fed sorters that positions bottom-mounted sensors, along with light sources and backgrounds, strategically away from product splatter. With a radical new design that keeps these surfaces clean, in-air viewing is sustained throughout the long production cycles in the most aggressive production environments. Blind spots are eliminated and 100% surface inspection is maintained as accurately after equipment sanitation as it is after several hours and days of continuous operation.

FM and Defect Discrimination

Both incremental improvements and a step change are enhancing the sorter’s ability to consistently differentiate FM and defects from good product. Today’s advanced digital sorters feature next-generation four-channel cameras and laser sensors, which offer twice the resolution of previous generation systems. Higher-resolution sensors can detect smaller FM and defects, while the dedicated infrared channel on the cameras can be leveraged to improve differentiate between FM and potato skin from potato flesh.

The step change is introduced on sorters that incorporate the new multisensor pixel fusion detection concept. Pixel fusion uniquely combines pixel-level input from multiple cameras and laser sensors to more clearly differentiate good product, FM and defect. It allows a sorter to detect and remove even the most difficult-to-detect FM and surface defects with fewer ‘false positives’. It also enables a sorter to identify the specific FM type for the purpose of automatically alerting when a particular incident (FM finding) occurs. This capability is of most value when the tolerance for FM is particularly tight, such as when inspecting final product quality at the end of the production line, immediately upstream of packaging.

For potato processors interested in adding chemometric analysis to their detection capabilities, multispectral and hyperspectral imaging technology is the solution. Already available as an option on ADR systems, combining hyperspectral imaging with traditional sensors allows invisible product conditions to be identified and measured. The step change enabled by this technology is the ability to detect a high concentration of sugars (e.g., sugar end defects), solid content and internal diseases with a digital sorter, using a combination of hyperspectral imaging, color cameras and laser sensors on a single platform.

Maintaining Grade

The primary job of any sorter is to maintain product grade, as defined by the processor, while maximizing process yield. A powerful tool in this pursuit is intelligent Sort-to-Grade (STG) software, which is constantly evolving to help potato processors accurately maintain complex final product specifications without operator intervention.

Simply speaking, STG allows a potato strip sorter to recognize and categorize every surface defect and the length characteristics of individual strips, intelligently performing every accept/reject decision for each strip based on how the outcome will impact the aggregate ‘in-the-bag’ product grade.

Accurate Ejection

Supporting all the technological advances realized in FM and defect detection, improvements in the sorter’s ejection systems have kept pace. The most modern ejection systems are customized to match the needs of the application, with air nozzles spaced ideally for each product type. Intelligent software on advanced sorters adjusts the power and duration of the air nozzles to suit the size, shape and weight of each object targeted for separation. Smart sorters can actuate one or more nozzles using contour-based or centroid-based calculations to target precise hit points on the object, maximizing removal accuracy and preventing the targeted item from disturbing the trajectory of other objects around it. Matching superior detection accuracy with superior ejection accuracy simultaneously maximizes product quality and minimizes the amount of good product inadvertently going into the reject stream.

Easing Use

Digital sorters are becoming more sophisticated in their ability to detect and eject FM and defects, while their increased processing power is being harnessed to ease use and enhance automation. Navigating with swipes and taps, much like on a smartphone or tablet, the newest sorters feature a UI that is so intuitive, an operator with minimal skills can master the full extent of its capabilities in less than one hour. UIs can provide different views and functionality access to users of various levels, depending on their needs.


For potato processors looking to enhance product quality, increase yield, reduce training requirements and improve operational efficiencies, the newest digital sorting equipment is worth close investigation. Those who recognize and implement successful new technologies ahead of the rest – the early adopters – put themselves in a position where valuable competitive advantages can be won.

 You can read more in our print magazine Potato Processing International (March/April 2017)! 

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