Proteins are important nutrients, and as the population grows, we need more food and feed with high protein content and good quality. A technology called spectroscopy can help us measure the quality of the proteins faster and more efficiently.
The increasing demand for proteins in food and feed requires precise protein analysis to ensure food quality. Efficient protein utilization and reduction of food waste are crucial to achieving more sustainable food. However, the food industry often relies on slow and costly laboratory-based methods for the quality analysis of food. Now, researchers are working to find rapid and cost-effective sensors that can provide accurate and reliable measurements of the quality of our food.
A suitable method is Fourier Transform Infrared (FTIR) spectroscopy. FTIR sensors are faster and require less preparation of the samples. The challenge with this method is that water in the samples can disrupt the measurements because water absorbs radiation in the same way as proteins, especially while measuring proteins in liquid food matrices. In his doctoral dissertation, Bijay Kafle tried to solve this by using a dry film sampling approach. Using the dry film FTIR method, the water is physically removed before the analysis, minimizing the water interference, and resulting in more accurate measurements.
"This innovation is crucial to meet the needs of the industry, optimize protein resources, and support sustainable food production practices," says Bijay Kafle, a research fellow at the Norwegian University of Life Sciences (NMBU).
Provides good and accurate results
The main goal of Kafle’s dissertation was to study the potential of dry film FTIR spectroscopy for industrial measurements of food quality. In his dissertation, he focuses on using dry film FTIR to analyze industrially produced protein hydrolysates from enzymatic protein hydrolysis (EPH), further exploring this industrial process with FTIR spectroscopy, designing and developing a portable dry film FTIR system tailored for industrial use, and developing new applications relevant to the industry. A lot of nutrients are left in the rest-raw materials which come as side streams from the fish and poultry processing industries. These leftovers are enzymatically hydrolyzed to obtain value-aided peptides and amino acids.
"We used dry film FTIR spectroscopy to study protein hydrolysates, which are proteins that are broken down with the help of enzymes. The water phase of the sample contains peptides and free amino acids and their characterization is really important for quality control. We found that the dry film FTIR method gave better results and could predict important quality parameters such as average molecular weight, low molecular weight constituents, and collagen content. We also used the method to understand variations in the process of enzymatic hydrolysis," says Bijay Kafle.
Differences between FTIR-ATR and dry film FTIR
In the study, Kafle compares two sampling strategies, FTIR-ATR and dry film FTIR. He tested them on laboratory-based salmon hydrolysates and industrially produced poultry hydrolysates (residual material from salmon and poultry that is broken down with the help of enzymes).
Dry film FTIR proved to provide better chemical resolution, probably because the water was removed, and more accurate predictions of key quality parameters, such as average molecular weight (AMW). Dry film FTIR also provided a more reliable analysis of the samples with a more complex protein composition, such as poultry hydrolysates, where information from the amide I band in the FTIR spectrum is crucial.
FTIR-ATR proved to be suitable for predicting AMW and Brix values in samples with a simpler protein composition, such as in salmon hydrolysates. Here, the calibration models were more dependent on FTIR bands that were minimally affected by the water in the samples.
Kafle also explored dry film FTIR as a tool to understand industrial processes in an enzymatic hydrolysis facility. Protein hydrolysates produced from the enzymatic breakdown of poultry rest raw materials, were characterized in terms of quality and further investigated to provide an understanding of process variations.
"The calibration models that were developed based on regression using the FTIR spectra of the protein hydrolysates showed a good ability to predict key quality parameters such as AMW, low molecular weight components, and collagen content," says Kafle.
Dry film FTIR effectively distinguished large variations in raw materials (i.e., turkey and chicken carcasses) and the significant effect different enzymes have on the key quality parameters.
"This shows the potential of dry film FTIR to characterize the quality of industrial protein hydrolysates and to monitor and control the hydrolysis process," says Kafle.
Created a portable system for the industry
A central part of Bijay Kafle's dissertation has been to develop a portable FTIR system that makes it possible to make dry film measurements on the assembly line in industrial environments. After successful laboratory tests and comparisons with a commercial FTIR system using industrially produced protein hydrolysates, the portable dry film FTIR system was tested in an enzymatic hydrolysis plant to measure protein hydrolysates on the assembly line.
"The calibration model showed a good ability to predict average molecular weight (AMW) on industrial samples. There were no significant differences in prediction ability between the portable dry film FTIR system and the commercial laboratory system," says Kafle.
The portable dry film FTIR system was also used to analyze lactate content in cell culture media. This indicates that there is a wide range of possible applications for bioprocess monitoring.
"The dry film FTIR system should now be used to develop new industrial applications for protein and food analysis. One important area will be protein composition in milk," says Kafle.
Dry film FTIR spectroscopy has great potential for analyzing protein hydrolysates
As a whole, this dissertation has illuminated the potential of dry film FTIR spectroscopy for analyzing protein hydrolysates. Dry film FTIR provided better chemical resolution, promising results in predicting key quality parameters for protein hydrolysates and increased understanding of process variations during industrial enzymatic hydrolysis. The development of a portable dry film FTIR system makes it possible to incorporate the system into process lines for potential in-line measurements after further automation of sample preparation and drying process. Dry film FTIR spectroscopy therefore proves to be a reliable tool with great potential for rapid sample analysis, quality control and process monitoring in industrial environments.
Bijay Kafle defends his doctoral thesis "Dry film FTIR spectroscopy for industrial measurements of food quality" on 28 June 2024. Read more about the event here.