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TOMRA Food Nut eBook 2020

How processors can sort green beans when the requirements keep changing

The two main goals of vegetable processing, food safety and product quality, are sacrosanct – but the goalposts keep moving.

Every incoming truck load of green beans might vary in quality. Due to slightly different weather, soil or growing conditions, there might be more or fewer discolorations, or a sudden influx of weeds or even insects. And because beans can be sold in varying quality grades and differing forms, product specifications also need changing. This complicates the day-to-day business of processing, but there can be no excuses: no matter how much or how often circumstances change on the processing line, product imperfections must be detected and ejected. 

During years of frontline experience working closely with processors, TOMRA Food’s sorting machines have been developed to deal with such variables. It is fair to say that today’s sorters are amazingly flexible. One reason for this is sophisticated software programs, which have pre-programable machine controls. Another reason is the wide-ranging technologies employed by sorting machines, which enable an equally wide range of specialized functionalities.




On the software side, the programs that run sorters’ automatic functions can also be manually pre-set by operators via touchscreen controls. This facility enables the machines’ detection and rejection parameters to be easily and precisely tailored to each new batch of vegetables coming down the line, minimizing downtime between batches as well as maximizing yields.

Another benefit of sophisticated software is that the machines are getting more intelligent. A good example of this is the web-based platform TOMRA Insight. This turns sorters into connected intelligence centers that generate valuable data, then processes the data into actionable information. Another recent innovation tool is SCADA (supervisory control and data acquisition) systems, which connect sorters to a control center where fault-alerts are flagged-up immediately and can be responded to remotely. These developments herald the arrival of a new era of machine networking and self-learning which will further enhance sorting efficiencies.

Then there is the hardware, the machines themselves. Developed and configured for different purposes, these can handle all manner of sorting tasks from one end of the processing line to the other. This versatility is made possible by diverse defect-detection technologies: pulsed LED light sources, high-resolution cameras, near-infrared cameras, and lasers are all deployed by today’s sorting machines, sometimes independently, sometimes in combination, depending on the designated task.

And the sorters best suited to green beans? There are up to three machines especially worth knowing about here: the Sentinel II, the TOMRA 5B, and the Blizzard.  


The Sentinel II is a pre-sorter which prevents defects from entering lines handling washed green beans. This machine uses the latest illumination and detection technology, with pulsed LED sensor arrays. Adjusting these sensors with a simple user interface makes it possible to control the removal of a wide variety of foreign material such as corn cob, grasshoppers, mice and other vermin besides stones, wood, plastic, glass, metal. Fast and sturdy ejection fingers ensure the effective removal of these critical defects. 

The Sentinel II is available in three different sizes and outperforms its rivals in sorting efficiency, capacity, and durability. In fact, with a capacity range of 8 to 22 MT per hour, this sorter has the highest throughput-to-machine-width ratio in the industry.

The state-of-the-art TOMRA 5B is used widely for processed green beans prior to or after blanching. As the beans move along the machine’s belt, foreign material and imperfect produce are detected by camera and laser technology. The cameras focus on any type of discolorations or shape defects, like stems or stalks while the laser targets any type of foreign matter. The laser technology can even inspect based on the level of chlorophyll, improving not only efficiency but yield all together. High speed air ejectors accurately remove these defects in a smart way, increasing removal efficiency while minimizing rejection of good product.

TOMRA 5B-View 1-HR

Like a professional photographer taking pictures with intensive surround lighting and reflective underground, the TOMRA 5B inspects objects under a dome of surrounding LED light, on a reflective sorting belt. Process engineers at customers have reported that this allows them to detect very subtle color variations and very small defects, resulting in premium quality sorting.

Operators using the TOMRA 5B have frequently applauded the intuitive user interface, which novice operators find easy to operate, while also giving expert users access to a broad set of sophisticated sorting settings.         

After the freezing process and prior to packaging, the Blizzard sorter, with the latest-generation high-resolution pulsed LED optical system available on the market, submits the green beans to the last, stringent inspection. This removes any types of discoloration or shape defects that might have slipped through any part of the supply chain. Foreign material that might be introduced during the process, such as pallet wood, blue liner, cardboard, or plastic, is kicked out. By having both color and NIR capabilities, the Blizzard can distinguish bad from good according not only to color but also structural differences.       

These machines, and others in TOMRA Food’s portfolio, enable vegetable processors to tackle varied sorting tasks by deploying varied technical solutions. Hygienic design remains paramount for the food industry and must therefore be implemented without any shortcuts. This means there’s a perfect solution available, whatever comes rolling down the line.  

Topics: Sorting Technology, vegetables, TOMRA 5B, green beans

Jeffry Steemans

Written by Jeffry Steemans

Global Product Manager - TOMRA Food