Visionary thinking

by Alex Prömer
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Mycotoxins can cause dizziness, vomiting and even partial paralysis if consumed. When moisture and temperature create the right conditions, microscopic fungi can produce mycotoxins (literally “fungus poison”).

DON (deoxnivalenol — often called vomitoxin) is a prevalent mycotoxin. It can be found in foodstuffs and animal feed that come from affected grain crops.

The bad news is mycotoxins are highly resistant to temperature treatment and conventional food processes such as freezing and cooking. The best course of action, of course, is to make sure infected foodstuffs never get near our dinner tables in the first place. New optical sorting technology is helping to do just that.


An optical sorting solution consists of a feed system, inspection system and rejection system. The feed system (i.e. small input hopper, infeed vibrator and chute) moves grains to the inspection and ejection systems in a controlled manner. Grains are inspected after they have left the end of the chute.

The inspection system consists of digital cameras, foreground and background lighting. It measures the energy from each grain kernel as they pass in front of the cameras. Responses are processed by a data processor, which identifies defects in the product stream and locates these defects.

The ejection system has a series of air ejectors. Good grains are allowed to pass through unhindered, while pre-identified grains with defects are rejected. The ejection system uses the location information from the image processor to aim short bursts of compressed air at the defects, removing them from the product stream.


The challenge facing manufacturers of optical sorting equipment is to provide processors with lean production technology that ensures high product quality and maximum yield, while providing greater flexibility, continuity and energy savings.

Following intensive research and development, Buhler has developed the

Sortex optical sorting system which enables grain processors to identify grain infected with DON with much greater precision. It also identifies impurities such as plastics, wood and other undesirable materials.

Buhler Sortex’s goal was to deliver a concept that met the diverse needs of all whole grain and specialty millers. So as well as rejecting foreign seeds and grains, the technology removes spelt, straw and oats, which improves the end-quality of cereal products (i.e., flakes) significantly.

Mechanical sorters cannot remove kernels that are highly contaminated

with DON, as these are the same size as other kernels.


To illustrate the benefits offered by this type of optical sorting, take 80,000 tonnes of wheat and set a cleaning capacity of 12 tph. Using conventional/ mechanical sorting, screenings would amount to about 2-3%, which gives a yield of 78,000 tonnes.

Compare these figures to Buhler Sortex’s optical sorting screenings, which are at least half that amount, resulting in significantly more end product, the quality of which is 0.5-1% better. Processors are also able to plan their maintenance more effectively, because yearly production volumes are reached quicker.

Not only do optical sorters help guarantee mycotoxin-free grain and maximum yields, they also bring significant maintenance savings because of an extremely long-life ejector system. In the case of the SORTEX Z+, careful power-management features minimize electricity use, while small high-pressure ejectors reduce air consumption significantly.


The introduction of optical sorting has captured the interest of grain processors worldwide who previously had to rely on centuries-old mechanical methods.

An increasing number of grain processors are integrating optical sorting solutions — and not just for the higher yields and better quality they provide. Since Buhler Sortex’s optical sorting solutions have no moving parts, there is no need to replace mechanical parts. This saves costs and enables continuity, because downtime is minimized.

Moreover, optical sorting solutions run consistently, because they are looking for color differences rather than physical attributes.

They require minimal adjustment, because they have self-calibration and product color tracking for stable operation without adjustment. They also use less energy, because they use electronics rather than heavy motors. For a given wheat quality, the improved stability leads to better yields, too.


Those involved in cereal grain cleaning have been facing many new challenges in recent years, mainly driven by the need (regulatory and otherwise) for consistently high quality, more discerning consumer preference and the need for processors to maximize their yields while reducing costs.

A change in growing methods has also brought about a growth in blights that cause mycotoxins. Optical sorters, such as Buhler Sortex’s, are helping to make life easier – and more profitable – for processors throughout the world.

Alex Prömer is sales support manager for Sortex Grain. For more information, e-mail  or visit