Norwegian seaweed industry has great growth potential. Firstly, the Norwegian coastline is the second longest worldwide, and includes many areas suitable for seaweed, which prefer the cold, nutrient rich water with high salinity we have here. Secondly, we have a deep understanding of the life cycle of sugar kelp (Saccharina latissima) and winged kelp (Alaria esculenta), which makes it possible to cultivate them at ropes deployed in the sea. The moment seaweed cultivation enters the picture, it is possible to increase the accessibility of this resource more sustainable, compared to harvesting from wild growing populations. Seaweed cultivation in Norway has been shown to have minimal impact on coastal ecosystems, and considering the only factors needed to grow seaweed are sun light, CO2 and natural occurring nutrients in the sea, it is in principle possible to cultivate millions of tons of seaweed. Norway is currently the biggest producer of cultivated seaweed in Europe (336 tons kelp was cultivated in 2020), but to scale up this industry we are depending on a well-established seaweed market. To develop this marked further, it is necessary to investigate novel application areas for cultivated seaweed, in addition to the traditional focus on food and feed.
Brown seaweeds have a strong, but flexible structure, thanks to unique biopolymers in the cell walls, such as alginate, fucoidan and cellulose. In addition, the seaweed consists of other chemical compounds, such as proteins, pigments, minerals, and the storage products laminarin and mannitol. Several of these compounds have reported bioactivities, such as being antiviral, antibacterial, and anti-inflammatory, making seaweed an interesting candidate for pharmaceutical industry. However, despite several studies reporting bioactivities in seaweed extracts, few of these compounds reach clinical studies or application in products available at the market. To make an upscaling of the Norwegian cultivated seaweed industry possible, it is essential to identify and remove critical bottlenecks.
The greatest hinder for an expanded use of biopolymers and other compounds from cultivated seaweed, is the lack of standardised extraction and characterisation. The lack of well-established purification protocols makes it difficult to evaluate if an observed bioactivity is due to the actual seaweed compound, or just co-extracted impurities. Additionally, seaweed constitutes a dynamic biomass, changing its composition a lot during the growth season, something a comprehensive sampling- and characterisation campaign in this project has shown. The harvesting season for cultivated seaweed is short compared to wild growing seaweed. Where wild Laminaria hyperborea can be harvested all year round, cultivated S. latissima and A. esculenta can only be harvested from mid-April to mid-June, which creates a very hectic processing period during spring. Another obstacle for use of especially alginate from cultivated seaweed, is the lower fraction of guluronic acid in the alginate chain compared to wild L. hyperborea, a trait giving poorer gelling properties. To truly understand the relationship between the chemical structure and biological function in a seaweed compound, one depends on good characterisation of both the seaweed biomass and the extracted compounds.
So far in this PhD-project, standardised characterisation methods of the seaweed biomass have been developed, and standard extraction-, purification-, and characterisation protocols for alginate and other biopolymers from cultivated sugar kelp and winged kelp have been established. In addition, two extensive acid conservation experiments have shown that with the right conditions, it is possible to elongate the processing season for cultivated seaweed by 4 months, without affecting the quality of the seaweed alginate and cellulose. Studies on upgrading of alginates from cultivated seaweed with enzymes is ongoing, aiming at improvement of the alginates gelling properties and increase their value at the market. The data is now presented in two publications, that currently are under review. In the project's next phase, functional properties of the biopolymers will be closer studied, and species-specific variations in chemical structures will be further investigated. Upgraded alginates with enzymes will be included in these analyses.