How the TOMRA Field Potato Sorter Improves your Sort

Field Potato Sorter (FPS)

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Potato sorters used in fields today are inefficient, expensive to operate, and high maintenance. Many of these machines require several people to operate them, and weather conditions must be just right for optimal sorting. Additionally, the machines fail to adequately separate foreign objects from the harvest, which reduces the yield and increases storage costs. Growers then run the risk of rejection and return from the processing plant.

TOMRA’s Field Potato Sorter (FPS) overcomes all of these issues.

The FPS is a sensor-based sorting machine for unwashed potatoes; it removes soil clods, stones, and foreign objects. The machine’s technology identifies and compares the physical characteristics of good product and foreign material, and sorts based on these patterns.

To deploy a sensor-based sorting machine for unwashed potatoes, most companies have a set of essential requirements:

Whatever your role in the potato value chain — key decision-maker, chief executive officer, technical support specialist, or grower — after reading this, you will understand how the FPS fulfills these requirements and why your organization will benefit from using it.

Seeing the benefits of the FPS

Sorting unwashed potatoes is a critical step in the potato business because the quality of the product depends on how well that classification is done.

Growers and packers currently sort their unwashed potatoes using two kinds of sorters: optical (digital) sorters or non-optical (mechanical) sorters.

But they have two main challenges when using these sorters:

The following sections explain how the FPS addresses these critical issues; other benefits to using the FPS are also discussed.

Field Potato Sorter in action

Weather Conditions Don’t Matter

The FPS can classify and separate potatoes from foreign objects, regardless of the weather conditions. Using its unique detection mechanism and object analysis techniques, the FPS separates potatoes from stones and soil clods, even when there is more soil adhesion because of poor weather and harvesting conditions.

Other sorters have to stop or delay the harvest during poor weather conditions. The harvesters tend to lift more soil and form more soil clods in wet conditions. This situation can cause higher foreign object loads to be included. Manual picking of this increased load means a reduction in throughput and therefore slower harvesting and, occasionally, halting work. With the FPS, which can deal with higher reject loads, there is no need to slow down or stop.

No Need for Constant Adjustments

Competitors’ sorters require significant adjustments as field conditions change, and it can be challenging to achieve repeatable results. Unlike these sorters, the FPS has a touchscreen user interface that provides product sorting data.

When fewer adjustments are needed, the sorting process becomes more efficient. For example, only one adjustment is necessary when the soil covering the potatoes becomes very heavy. The adjustment can be made on the touchscreen without stopping the sorter. The user then sees the result of the adjustment immediately on the screen. Mechanical adjustment is not necessary. In general, an adjustment isn’t needed more than once a day.

Because the FPS needs less monitoring than other sorters, growers and packers can attend to other tasks while harvesting potatoes. They just need two minutes to check the machine’s settings each morning when starting it up.

Always Ready to Work

Growers and packers must weigh the cost to acquire, train, and retain labor against the cost of purchasing and maintaining automation technology.

With labor hard to find, typical labor savings using the FPS is approximately 80%. You no longer need to hire staff, train them, process timesheets, check attendance, and process payroll costs. The FPS is always ready to work.

For example, a typical sorter will have four to five people working on a 60 to 70 tonne per hour throughput removing stones, clods, and foreign objects. The FPS reduces the required number of people to one or two. In the long run, the cost of the FPS is offset by the labor savings.

Potato sorting at Nedato (The Netherlands) with TOMRA FPS.

Time Saved

The number of hours you save by using the FPS depends on the field conditions and weather conditions, but you could realize savings of up to 30%. Growers typically spend 10 hours a day on harvest and storage. With the FPS, this can be reduced to 8 hours per day.

The sorter can be used on product going into storage and out of storage, creating savings on both sides.

Yields Increase

Rocks and soil clods can damage potatoes during long-term storage, resulting in reduced yields. The FPS increases the yield by detecting and removing rotten product and the smallest foreign objects from production lines. Exact numbers are not available to know the extent of damage caused during storage, but common estimates put the loss at up to 1% yield loss due to storage.

Poor or insufficient removal of stones, soil clods, and other foreign objects leads to higher yield loss and storage costs. For example, in 6,000 tonnes of harvest, the removal of foreign objects (about 5% of the total weight) means 300 tonnes of material that does not have to be cooled for storage. The removal of this material also results in efficiency in storage space.

Risk of Load Rejection Reduced

Growers who provide potatoes to the processing industry seek to eliminate the risk of load rejection and return because foreign object levels exceed specifications. The FPS can reject foreign objects more efficiently and more accurately than human pickers, reducing the risk of rejection and return from the processing plant. Higher-quality loads are delivered to the plant.

Intuitive Graphical User Interface

Most food sorting machines contain complex sensors; any small adjustment error can significantly affect yield and cost. To overcome that, TOMRA created the TOMRA ACT, a more intuitive and less operator-dependent sorting user interface.

Thanks to this system, the FPS’s screen provides simple controls and feedback. The touchscreen controls make it easy to get data from the sorting process and to adjust the parameters to get the results you need.

The screen allows you to see at glance:

The screen updates every 5 seconds with information about the percentage of potatoes accepted and percentage of material rejected. This allows the grower to know the efficiency of the harvester and the quality of the loads from the field.

The TOMRA ACT received the 2015 International Design Excellence Award(IDEA)


High-Capacity Sort

Instead of using conventional near-infrared (NIR) spectroscopy to detect and reject rotten potatoes and foreign objects, the FPS uses multispectral NIR sensors to scan each item in flight (when the product falls from the infeed belt to the accept conveyor belt).

Using the next generation of spectral imaging — biometric signature identification (BSI) technology — the FPS identifies the material’s unique fingerprint. The BSI technology illuminates every object that crosses the inspection zone and detects the object’s reflection. The reflection is then analyzed in the spectral space by a NIR sensor to determine whether the object is a potato or foreign object. TOMRA’s new inspection technology minimizes false rejections.

Even if the potato has a lot of soil on it or looks like a foreign object, the BSI module will detect it as a potato

Gentle Product Handling

All physical contact with potatoes after the harvest deteriorates their quality. This can reduce the product’s value and negatively affect the next processing steps. So, gentle handling must be a primary focus for growers and packers.

The FPS is designed to reduce the amount of handling needed to sort potatoes. As material is picked from the field, the accepted product passes untouched through the sorter while intelligent low-wear finger ejectors reject foreign objects.

The design minimizes the drop of the potato from the infeed belt to the accept conveyor belt, which is unique in construction. The machine uses a pintle belting — a soft belting material that absorbs the impact of the potato hitting the belt to avoid damage to the product.

The removal of foreign materials such as clods, stones, and other foreign objects is crucial, not only for improving yield but also for minimizing the damage to delicate potato tubers during handling and storage.

FPS Working principle

Low-Energy Consumer Solutions

Two systems are responsible for the significant energy efficiency of the FPS: the illumination and detection system and the electro-pneumatic finger ejection system.

Illumination and Detection System

Most sorters use an enormous amount of halogen lighting to do the same work of the FPS, but the FPS uses about ten times less energy because of the Flying Beam technology.

With the Flying Beam technology, the FPS has to illuminate only one spot instead of the whole region of imaging. Its scanning beam moves across the products at an extremely high speed, and it inspects potatoes and foreign material as they drop off the infeed belt.

The Flying Beam technology use up to 40 times less illumination power than other technologies and thus uses less energy and generates less heat output. As a result, the scanner does not have to be cooled as the scanners in most other sorters do.

Electro-Pneumatic Finger Ejection System

Many sorters use compressed air to reject foreign objects from the product flow. Compressed air shoots through a nozzle to remove the object.

A compressed air system has several disadvantages:

The FPS uses an air cylinder and finger system. The compressed air shoots out through a valve at very high speed, fills a cylinder, and pushes the finger to eject the foreign material. After the foreign material is removed, the finger snaps back into its resting position, and the product flow continues.

This process occurs at very high speed, so the FPS can sort rejected objects while remaining extremely energy efficient.

The FPS consumes less than 6 kw/hour when sorting 70 tonnes per hour. Additionally, it uses about one-tenth of the compressed air required for an air ejection system.


TOMRA’s FPS meets all the key needs of today’s companies, including:

To take the first step toward improving the quality of your sort, please call +32 16 396 396 or e-mail

TOMRA Sorting Food designs and manufactures sensor-based sorting machines for the food industry. Over 6,250 systems are installed at food growers, packers, and processers worldwide. More about TOMRA:

About Authors

Jorge Luis Alonso G. is a white paper writer for high-tech food industries. He is based in San Juan, Argentina.

Vicki Adang is an editor and writing coach. She is based in Indianapolis, USA.



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