Side-by-side trial proves Sortex camera technology offers superior performance on foreign material from foodstuff

21.08.2008 Traditional methods for removing foreign material (FM) perform adequately enough, but they have limitations. Foreign materials such as blue plastic, cardboard and light wood can be difficult to remove. “The pioneering technology developed by Buhler Sortex overcomes such difficulties, because it can recognise a wider range of FM. Even the smallest defects can be removed easily,” says David Adams, Buhler Sortex business development manager.

Buhler Sortex offers a menu of technologies that combine high-definition cameras, PROfile shape recognition, Smarteject™ rejection system, alternative feed systems and Mono or Bichromatic InGaAs cameras. These can be combined to meet the customer’s precise requirements.

Maximising efficiency and yield of frozen mixed vegetables
“Often there are stability issues with traditional sorting methods and they often require high levels of operator intervention,” Adams continues. “They can be difficult to set up and be costly.”

The biggest drawback, however, is the amount of good product that they remove into the FM stream. “This can be as high as 3% of the total product at the point of packing,” Adams reveals. “On a high-value product, such as frozen mixed vegetables, minestrone or paella, such a loss is unacceptable. Again, with a combination of the Buhler Sortex technology, this can be reduced to less than 0.5%.”

Listing other advantages, he cites simplicity of set up, lack of need for continuous adjustment, consistency and dependability in harsh, hot or dusty environments.

“There’s no doubt, recent technologies are superior to early optical sorter cameras,” Adams adds candidly. “However, unlike earlier optical sorters, ours use a combination of technologies that together out-perform all others.”

The majority of sorting machines currently in use for detecting and removing FM from frozen vegetables rely on the detection of texture by using scanner technology similar to that used in bar code scanners.

Adams explains: “Different Sortex camera technologies target different foreign materials. And together with advanced shape feature processing, this provides superior detection of previously difficult to detect FM in vegetable mixes, together with reduced loss of good material and improved sorting stability.”

Case study – removing FM from blueberries
Recently, Buhler Sortex optical camera technology showed its superiority during comparative trials. Technical manager Ben Deefholts explains: “A potential customer was using laser technology to remove FM from blueberries. They were interested in upgrading.

“We installed a SORTEX K machine on a performance contract basis. The customer was not interested in removing immature berries or other colour berries. The aim was to maximise yield, while removing all FM.”

The SORTEX K, using new bichromatic cameras and InGaAs technology, was started up. Then it was fitted with a kit to enhance the removal of FM without detection of discoloured products.

“Results showed our ‘accept’ was cleaner than the customers current machine,” Deefholts reveals. “For some specific defects, we were far superior. Crucially, our yield-loss was typically 2-3%; compared with 5-10% for the laser machine. Our yield loss peaked at 6% when running very heavily contaminated ‘floaters’.”

The customer was interested to see what would happen when product colour changed slightly. “Apparently, their existing machine would fire out a lot of good product,” Deefholts adds. “With the SORTEX K, it made little difference. Adjustments were very easy to make,” he concludes.