A closer look

Near Infrared Spectroscopy has been a well-established technique for the agricultural industry for decades and is becoming increasingly important in the food industry. The next logical step is to take NIR from the lab to the production process, says Bruker Optics’ Dagmar Behmer.

The NIR technology offers a lot of advantages over classical analyses, since it is quick, cost-effective and safe, as no hazardous chemicals are used. It simply measures the absorption of near-infrared light of your sample at different wavelengths.

NIR also avoids the typical error sources of the classical lab methods, e.g. during the sample preparation stage. The beauty is that numerous parameters, such as protein, dry matter and fat, but also many others like amino acids, can be monitored simultaneously within a few seconds, saving thousands of Euros on wet chemistry every month.

Another issue is food safety. Although NIR spectroscopy is not a technology for trace analysis like for toxins, it will help the producer to constantly monitor the quality of the goods along the production chain - from checking the incoming raw materials up to quality testing the finished product. This will soon be as important in the food industry as it is already today in the chemical and pharmaceutical industry.

The benefits of NIR for production control

There is a strong trend to take the NIR spectroscopy on the line rather than taking the sample to the lab. Not only quality and safety issues, but also economic considerations motivate the producers to develop methods for the real time process analysis. One example is the analysis of butter. For butter it is important to stay as close as possible to the legislative target concentration of the butterfat. In Europe, this is around 84 percent, i.e. the producer is allowed to add up to 16 percent of water. Since water is the cheap ingredient, they strive to get as close to the target as possible. A process monitoring the water content with NIR can achieve that.

Another hot topic is the in-line analysis of liquid milk. Here we teamed up with Tetra Pak Processing Systems, a global player providing production solutions to the food industry. They utilise our technology with Tetra Alfast machines for standardisation and blending of milk in order to monitor and optimise product quality for dairy applications.

Taking NIR spectroscopy on-line

The implementation of NIR technology to the process can be quite complex. One crucial question is how to generate the reference samples. NIR analysis is a secondary method, which means that it cannot determine any parameter directly, but is dependent on correlating an NIR spectrum to a given reference value. These values are often difficult to get, especially for off-spec products. In the case of the butter analysis, it was easy to get good samples around 16 percent of water, but to deliberately de-tune the line to get other values was virtually impossible. So it took some time to collect a sample variety in order to build a robust calibration.

Quite often it is also not easy to find the best position of the NIR sensor. Here Bruker offers various possibilities of contact and non-contact sensors, which can be inserted into pipes and vessels or used over conveyor belts.

Another issue lies in the food sample itself: being a natural product, one has to take all possible variations into account in order to build a reliable measurement method. Those can be different seasons, different country origins or even different genetic variations. A process, which is monitored by NIR, will still need in the first months a random reference analysis to check the validity of the NIR results.

To ensure a good start for our customers, Bruker Optics has offices world-wide staffed with experts who have vast experience with the implementation of NIR applications on-line and in the lab.

Dagmar Behmer has an MSc degree in Analytical Chemistry and is Head of International Support in the NIR & Process technology group of Bruker Optics in Germany. She has 20 years of experience with NIR spectroscopy, focussing on food and agricultural applications.