Bühler optical sorter targets rising defects in rice

Designed and built in the UK, the machine has up to six modules, a patented feed system and what it claims is improved detection of defects, which are becoming more subtle and difficult to find.

In the past, it says operators could not distinguish between different shades of rice and have had to increase overall sensitivity to remove all subtle yellows and greys, reducing yield.

Export regulations​

Processors also face increased competition and consolidation of rice mills, plus greater pressure to meet demand for different levels of rice quality, including export standard.

Ben Deefholts, specialist, Bühler Sortex Rice, told FoodProductionDaily.com the company has always had an optical sorter for rice but has taken it one-step further.

“There are several things which effect rice contamination levels​,” he said.

“Some defects are caused by insect attack, and reduction of use of insecticides has had an effect. This mainly concerns small dark tips on the rice. Yellow grains are often caused by poor storage conditions or long periods in storage​. 

“Government programs and trading conditions often require storage of rice. When the stored rice is released back in the market, it often has higher contamination of yellow grains. This was the case in the Payment In Kind system in the US​.

Purple grains Thailand​

“Use of hybrid varieties see higher yields but can also lead to higher chalky rice levels. Fertilisers can also result in subtle colouring of the product and is thought to be the cause of purple grains in Thailand​.”

Bühler works with companies including Siam Indica in Thailand, which signed an agreement for 100 machines last June. Sortex S UltraVision went on sale this month.

“We developed additional features that were being asked for by customers; sorters that needed less attention and were easier to use​,” added Deefholts.

“Customers wanted to select which grains to accept and which to reject.  Bühler listened to these comments and, after several years of research, developed technology, allowing better detection of different types of defect and, using new sorting and control algorithms, to automate decisions (adjustment of complex controls) on which grain should be accepted and which should be rejected​. 

“It would not have been possible to incorporate these developments in existing designs, so we started from the ground up and created a sorter that was exclusively for processing rice​.”

The machine can also be used with Bühler’s Sortex ProSort software.

Changes in light levels​

“Intelligent Automation ensures the sorting performance of the sorter remains consistent, through changing conditions –such as changes in light levels caused by dust or changes in the incoming rice​,” said Neil Dyer, global product manager, Buhler Sortex.

“Without this feature, the performance of an optical sorter will degrade over time, unless a trained operator re-sets the machine to new conditions​.

“On a conventional sorter there may be dozens and dozens of different settings that need tweaking, which is both time consuming and complex​.

“Intelligent Automation constantly scans the incoming product and automatically makes the required changes to ensure optimal sorting performance, to the end of the batch​. 

“Sortex have been making automated sorters for over 30 years and are still the only company to offer this unique feature – Intelligent Automation is the latest development and only available on the Sortex S UltraVision​,” he added.