Optical Sorting: Latest Technologies Minimize Waste

Frozen food products have typically gone through most of the processing line before they are frozen. During processing, multiple sorting steps – both mechanical and optical – have already taken place and eliminated most foreign material (FM) and other unwanted products. Sorting on the frozen end usually occurs immediately prior to packaging. To ensure no FM makes it into a bag of final product, end-of-line sorting is an important safety step.

By Dan Orehov

Because each processor is unique, there is no ‘must have’ list that satisfies every application and budget. Popular options include the following:

  • Combine laser scanners and color cameras on a sorter to detect the widest variety of FM and defects.
  • Leverage sensors with higher resolutions to detect smaller FM and defects.
  • Add Pixel Fusion technology to find the most difficult to detect FM and subtle defects while minimizing false rejects.
  • Combine top-and-bottom- or front-and rear-mounted sensors to see all sides of each object to detect and remove more FM and defects.
  • Add Sort-to-Grade software to achieve the most complex final product quality specifications without operator intervention while increasing yield and eliminating mechanical length grading equipment.
  • Add Information Analytics software to turn a sorter into a data center that collects, analyzes and shares production and product data with the enterprise to optimize line management.
  • Add FM-Alert to inform the operator on the floor and/or the control room each time a piece of FM passes the sorter. It takes a picture of the FM and stores it in a database, enabling a processor to make process improvements to avoid these FMs from keep occurring again.

Sorting in different stages

A company contacted for this article, TOMRA Food, believes that the only way to be sustainable is to make sorts in different stages. In some industries TOMRA Food offers sorting machines in the pre-processing area, on the fresh side of the process area, and after the freezer. On every stage the company can help to increase efficiency, reduce the labor and be more sustainable. The second step takes into account the performance of the detectors. With BSI+ TOMRA Food provides an example of being more accurate in detection, and reduction in false detections. In combination with faster and accurate air guns, TOMRA Food can keep the rejection of good product to a minimum, which result in a higher yield and less food loss.

“No matter what type of frozen food you’re sorting, removal of foreign material and potentially dangerous matters is critical. TOMRA Food offers different sensor technologies. For the frozen food industry specifically, we have besides our laser and pulsed LED technology we have the newest technology Biometric Signature Identification or BSI+. This is a new technology which will detect more complex defects with a higher performance without losing more product. The standard BSI module is ideal for the removal of foreign material, while the BSI+ scanner deploys a wider spectrum and also detects visual irregularities identifying not only foreign material but also product specific defects,” explains Frank De Brauwer, sales manager at TOMRA Food.

According to equipment manufacturer Insort GmbH, it is very important to size the equipment correctly for the application. Under sizing equipment is a frequent cause of yield loss. Rejection mechanisms are already at a very fast speed and it doesn’t seem like there are huge development jumps in the pipeline of cylinder and air nozzle manufacturers. Processing speed is increasing and new and more powerful GPU processing technology is being developed for automotive industries, etc. which the sorting industry will benefit from. A quicker and more accurate way of detection (more data, better algorithms, etc.) will be the foundation of the next big improvements to sorter speed. Sorters have a huge impact on yield and profitability of the production process. A good set-up is key for ensuring maximum yield. Recovery sorting and inline quality control in real time are further essential contributors. Providing the processor quickly with the information needed and allowing for adapting the sorting process to best meet the target are a must.

“The diverse range of FM that the frozen food industry is dealing with on a day to day basis requires the most modern, reliable and stable equipment in order to be efficient. NIR technology is essential for a good FM detection on any sorter. Black and white, RGB and laser technology have proven to be inefficient when it comes to FM detection on the highest level,” explain Insort experts. “Multispectral NIR camera systems are a big step forward from these technologies, but the wider the range in the NIR spectrum and the more data points generated the better. This is why Hyperspectral Imaging proves to be the best technology currently available in the industry for FM removal. Insort is the first and only company applying this technology in the frozen food industry under the Chemical Imaging Technology (CIT®) brand. With this technology any type or organic and inorganic FM can be detected with highest accuracy independent of size shape, surface or density. Plastic, stones, wood, plant debris, metal, rodents and even glass are detected with highest reliability. In addition to the unmatched detection performance CIT® makes it possible to teach the whole range of the good product in one model, covering all varieties, seasonal and natural changes of the raw material. The combination of CIT® and Safeguard Drop Gates on the Sherlock Hybrid, set a new benchmark in FM removal efficiencies and food safety in the frozen food industry,” they add.

To read the full article, please access your complimentary May-June issue of Frozen Food Europe here.

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