| dc.description.abstract | Global human population is projected to increase by more than 34 % to over 9 billion people by 2050.
As food, feed, fuels, and pharmaceutical sources are crucial to support this population increase, researchers are putting efforts in to finding novel sustainable ingredients and means to produce these valuable resources. Currently, there is high focus on macroalgae as an alternative sustainable ingredient due to its positive contribution to ecosystem preservation, particularly in reducing greenhouse gases and
in bioremediation. Norway has an extensive coastline and an already established competence in marine raw materials processing and related technologies and thus have great prospects in macroalgae cultivation and value addition. The large-scale utilization of macroalgae, particularly in the food and pharmaceutical industries, will require continuous supply of the macroalgae biomass. However, harvesting is currently done seasonally (usually between the months of April to June) in Norway.
Therefore, it is imperative to develop suitable low cost and low energy methodology for preserving the harvested biomass for long periods, while maintaining an intact chemical composition. The aim of this thesis was to investigate the storage stability of brown macroalgae – Saccharina latissima, preserved for a long period (approx. 2.5 months) and to determine the effects of different pretreatment methods such as ensiling with different additives, microbes, and chemical stabilizers, on the general sensory properties and chemical composition. Another aim was to determine the bioactivity of fucoidans – an important biomolecule found in brown macroalgae. To do this, the macroalgae samples were subjected to 20 different treatments and stored vacuum packed for approx. 2.5 months. Afterwards the samples were physically analysed to check for colour change, smell, and fungal growth. Compositional analyses were conducted to assess any differences in compositions due to the different pretreatments. And subsequently, extraction of fucoidans and bioactivity analysis in head kidney leukocytes of Atlantic salmon was conducted. The results indicated that higher volumes of the additives were generally more effective in preserving the samples than lower volumes. Furthermore, although freezing is an effective preservation method, it is not feasible for larger volumes of macroalgae biomass, due to high energy and space requirements and high associated cost. Instead, preservation using formic acid 85 % was the most effective method based on the amount of fucose (major constituent of fucoidans) and purity of the fucoidan-rich seaweeds extracts. The other effective pretreatments were ensiling with Sil-All® 4x4, no additive (storing at room temperature), GrasAAT® Plus and GrasAAT® Lacto. Finally, the bioactivity of fucoidan-rich seaweeds extracts from S. latissima was confirmed based on its ability to induce an upregulation of the tnfɑ gene in head kidney leukocytes from Atlantic salmon. | |
