A second life for fish processing by-products
Fish processing generates a large volume of biological by-products which, depending on the species and processing method, can account for 30–70% of the total fish mass, and the effective use of these streams remains a significant challenge for the sector (EUMOFA, 2025*). At the same time, the need to replace plastic packaging with more environmentally friendly alternatives is becoming increasingly urgent.
The idea behind the project “Extraction of Fish Protein Hydrolysate and Its Condensation with Plant-Derived Catechol Derivatives for the Development of Improved Starch/Protein-Based Food Packaging” (No. 23-00-U2021902-000001), implemented at the Latvian State Institute of Wood Chemistry, lies at the intersection of these two challenges: is it possible to develop new food packaging materials from locally available, low-value biological resources?
Within the project, our scientists are working in cooperation with the Kuiviži Fishermen’s Association, using fish biomass and wood resources sourced in Latvia. Fish protein hydrolysate – an oligopeptide-rich protein mixture – is obtained from fish processing by-products and serves as a potential raw material for new biopolymer materials. In parallel, natural compounds containing so-called catechol units are extracted from black alder and pine bark.
In the laboratory, these two components—fish proteins and wood bark extracts – are combined to form thin biopolymer films. Such films represent potential prototypes for packaging materials. During the research process, various compositions and processing conditions are tested in order to determine how to obtain materials that are as strong and flexible as possible.
A biopolymer packaging material prototype developed by LSIWC researchers, made from fish proteins and tree bark extracts
The results obtained so far show that the process is not straightforward and that not all solutions perform equally well. For example, films produced from fish protein hydrolysate proved to be flexible but mechanically weaker than films made from collagen or gelatin. The project coordinator, Dr. chem. Māris Lauberts, explains that this is related to the structure of fish protein hydrolysate: the protein chains it contains are relatively short, making it more difficult to form a stable material matrix. Nevertheless, these findings are an important part of the research, as they clearly highlight the key challenges and indicate the directions for further development. “In future studies, we plan to improve the structure of the fish-based material to make it more robust. This means isolating high-molecular-weight fractions from fish biomass, as well as using high-molecular-weight proanthocyanidins from pine bark as a natural source of catechol units,” explains Dr. Lauberts.
Collaboration and knowledge transfer are also essential elements of the project. The involvement of fishermen in the preparation of fish biomass and the work of scientists in the laboratory make it possible to assess the entire process – from raw material sourcing to material testing. Alongside the research activities, the project team has delivered lectures to school pupils and students and participated in public events, explaining how science can help address practical environmental and resource-use challenges.
The project will continue until mid-2027, with the aim of gradually bringing scientific solutions closer to practical application. The results obtained so far, as well as the research process itself, demonstrate that even seemingly low-value biological by-products can become the basis for innovation in future packaging materials.
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