This light reads the quality of raw materials from fish

Fish trimmings from slaughterhouses are transformed into useful oils and ingredients at the Norwegian biorefinery Biomega. 

They source the raw material, but the composition varies from delivery to delivery.

Some batches contain more skin and fat. Others contain more bone or muscle.

Such variation can cause unstable processing conditions and lead to unpredictable product quality.

This challenge was the starting point for the collaboration between Biomega and researchers at Nofima. Their goal is to make the quality of the final products predictable.

They are now testing advanced light technology that can provide faster and more precise insight into the composition of the raw material. This can help the company adjust the process even more precisely.

Light through pipes

The researchers used spectroscopic measurements, where light is sent through the raw material and quickly provides an answer about the content.

This allows the raw material to be sorted and processed with much better control.

The measurements were developed by researchers at Nofima. They have focused on two spectroscopic analysis methods: NIR, which involves near-infrared light. The other method, Raman, involves lasers that provide detailed information at the molecular level.

The new measurement methods make it possible to measure the quality of the residual raw material inside the factory's processing pipes.

This gives Biomega better control over fat and water. It becomes easier to deliver more consistent products from a highly variable residual raw material.

“Our aim is to develop a solution that gives better oversight of the quality of the incoming raw material. When we know the quality of the residual raw materials, we can adjust the process so that the final product is as similar as possible from batch to batch,” says Tiril Lintvedt, a researcher at Nofima and DigiFoods.

A specially designed pipe section enables measurements

At Biomega’s facility, a straight pipe segment has been replaced with a specially designed section.

The new section has two sensor probes mounted 50 centimetres apart. 

This distance was critical to ensure that light from the two probes did not interfere with each other’s measurements. One probe is connected to an NIR instrument, the other to a Raman instrument. Both send light into the stream of coarsely ground fish trimmings.

“What's new is that we can measure raw material quality directly in the pipeline as the material flows past,” says senior engineer Katinka Dankel at Nofima.

From the grinder to a closed system

In earlier trials, NIR measurements were taken at the grinder. That was impractical and difficult to keep clean. 

Now that the trimming mixture flows past the probes in a closed system, there is less mess and fewer disturbances.

“There was close collaboration between Biomega and Nofima to identify the best solution. We had a good dialogue about what was important when installing the instruments in the pipe. Biomega drew the final design and ordered the new pipe section,” says Lintvedt.

Once the special pipe section was in place, specialists had to find the optimal location for the parts of the instruments that are not in direct contact with the product. 

In fiber‑optic systems like this, the probe is mounted in the pipe, while optical fibers guide the light to the rest of the instrument, where the signals are read. 

At Biomega, the detectors were placed ten metres from the probes. This distance could be much longer without affecting the quality of the measurements.

In processing halls in refineries, this provides a major advantage, since the detectors that read the signals are sensitive to moisture and large temperature fluctuations.

The solution was a wall‑mounted instrument cabinet with ventilation that keeps the temperature stable and prevents moisture from entering.

“One of our goals is that the pipe measurements will help us adjust the process in real time and achieve more stable operation. Whether this alone will deliver a more consistent final product is still uncertain, but it may become possible over time," says Silje Steinsholm, a scientist at Biomega.

She explains that a major advantage is that they get more reliable figures for yield, even when the composition of the raw materials changes, especially when it comes to water content. 

"This provides better insight into how the process responds to different conditions, for example over the course of the year,” she says.

From the lab to the processing line

Extensive preparatory work was required before measurements could start at Biomega. 

An important part of this was developing calibrations, meaning models that translate the light signals into numbers for substances such as fat and water.

“We placed the probe in a half‑pipe channel, a pipe cut lengthwise, to simulate measurements inside the process pipes in the lab. We received frozen, ground fractions and clean bones from Biomega, which we blended into different residual raw material mixtures,” explains Lintvedt. 

The mixtures were run through the half-pipe channel while the temperature increased from 4 to 13 degrees.

All spectra were included in the calibrations so that the measurment models recognise the variations that occur on the processing line.

Lintvedt explains that the samples were first analysed with Raman and then with NIR. Spectra at different temperatures were included in the models to capture the temperature variation that is typical at Biomega.

“In this case, the highly variable material was challenging, but we have gained important knowledge for further development of Raman methods. Raman is little used in the food industry, so testing the technology on such a demanding raw material is an important step forward,” the researcher says.

What this means for Biomega

In the control room, operators monitor the process around the clock. They track pressure, temperatures, and a range of other process parameters.

With the new NIR sensor inside the pipes, they will also be able to obtain new valuable data and follow the raw material mixture in real time as it flows through the pipes.

The NIR measurements make it possible to anticipate practical challenges and diagnose problems that have already occurred. 

If the fat content is too high, for instance, the mixture quickly becomes thick and clay‑like. The measurements also make it possible to optimise the process. If there is a lot of water in the raw material, less water can be added later in the process.

Operators can adjust key parameters to achieve the best possible composition in the product.

For four days, specialists from Nofima and Biomega measured the composition of the mixtures flowing through the pipes.

“The analyses show that the NIR instrument gives us a clear picture of how the composition changes from minute to minute, so we can see what is happening inside the pipes as it happens and adjust in time to secure more stable product quality,” says Lintvedt.

This content is paid for and presented by Nofima The Norwegian Institute of Food, Fisheries and Aquaculture Research

This content is created by Nofima's communication staff, who use this platform to communicate science and share results from research with the public. Nofima is one of more than 80 owners of ScienceNorway.no. Read more here.

More content from Nofima:

• 

  Red algae grown in wastewater from fish-farming facilities could become sustainable salmon feed

• 

  Pumpkins are good for more than just Halloween decorations

• 

  This is how temperature affects a salmon's health and growth­

• 

  Study: Omega-3 and zinc is a powerful duo for salmon

• 

  Fish may turn yellow if frozen too fresh

• 

  Is it better if food is packaged in plastic or paperboard?