Indrek Adler, Early Stage Researcher at the Estonian Maritime Academy’s Blue Economy and Aquatic Resources Research Group, successfully defended his doctoral thesis on November 7, 2025. The research focuses on developing processing solutions for Baltic Sea blue mussels and establishes a scientific foundation for sustainable and circular aquaculture in the region.
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The global food system is facing major challenges related to sustainability, climate adaptation, and the transition toward circular bioeconomy principles. Adler’s research demonstrates that low trophic aquaculture (LTA) can play a key role in addressing these challenges by producing marine biomass efficiently and with minimal environmental impact.
In the Baltic Sea — a brackish and nutrient-sensitive environment — the development of LTA has so far been limited by biological and economic constraints. The local blue mussel species (Mytilus edulis/trossulus) are smaller and have thinner shells compared to mussels cultivated in saltier waters, which has restricted their commercial use in food and feed markets.
Photo: Loreida Timberg
The doctoral thesis aimed to create scalable and sustainable processing workflows tailored to Baltic Sea mussel biomass, transforming mussel farming from a mainly ecological service into an economically viable activity. The research developed a whole-organism, zero-waste processing model, combining mechanical disruption, gravity sedimentation, low-speed centrifugation, and micronization of the entire biomass.
Flavor enhancement was achieved through citric acid pre-treatment, and enzymatic hydrolysis was applied to improve bioavailability and functional properties. Analytical methods included biochemical composition, amino and fatty acid profiling, microbiological safety, sensory evaluation, and tests for prebiotic activity.
The results showed that the sedimentation–centrifugation workflow achieved up to 17.2% dry matter yield, with protein contents exceeding 50% of dry weight. Whole-biomass micronization produced fine powders (under 63 µm) with uniform texture and excellent sensory properties. Citric acid treatment reduced off-flavors such as metallic and muddy notes by over 50%, while enzymatic hydrolysis enhanced the growth of Lactobacillus rhamnosus GG and Bifidobacterium animalis by more than 80%, indicating mild prebiotic potential.
Seasonal trials revealed that autumn-harvested mussels provided higher protein content, better texture, and greater glycogen levels — emphasizing the influence of seasonality on processing quality.
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The findings confirm that Baltic Sea blue mussels can be effectively valorized into nutritious, high-value products through whole-organism and zero-waste processing. This approach links environmental benefits with economic potential, supports regional circular bioeconomy goals, and opens pathways for new functional ingredients and food innovations.
According to the Estonian Maritime Academy, the study contributes to the sustainable development of aquaculture in the Baltic Sea region, offering evidence-based guidance for policymakers, scientists, and industry stakeholders.
Supervisors: Professors Jonne Kotta and Kristel Vene.
Opponents: Senior Researcher Aleksandar Vidakovic, Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences (Uppsala, Sweden), and Associate Professor Tiina Paalme, Estonian Marine Institute, University of Tartu (Tartu, Estonia).
The defence committee recognized the thesis for its high scientific standard and practical value to the future of blue bioeconomy in the Baltic Sea region.