Introduction to the Special Issue: "Advance in Recovery and Application of Bioactive Compounds from Seafood".

Due to increased focus on a circular bioeconomy, full utilization of marine biomass, including side streams from the seafood processing industry as well as utilization of biomass that has not been used to a great extent in the Western world (e.g., seaweed), is receiving increased attention from both academia and industry [...].

Multi-Extraction and Quality of Protein and Carrageenan from Commercial Spinosum (Eucheuma denticulatum).

Seaweeds contain many valuable compounds that can be used in the food industry. Carrageenan is a polysaccharide which has been extracted from seaweed for centuries and is used as a texturizer in food and non-food products. However, seaweeds contain compounds other than carrageenan, such as proteins, which could also be extracted. This extraction should be done without compromising the industrial scale carrageenan extraction yield and quality. This study aimed at up-stream protein extraction from red seaweed Eucheuma denticulatum by using of an optimized enzyme-assisted extraction, including of an aqueous/enzymatic treatment followed by alkaline extraction, and then the commercial carrageenan extraction. The protein extraction efficiency of four enzymes was evaluated including Celluclast® 1.5L, Shearzyme® 500 L, Alcalase® 2.4 L FG and Viscozyme® L at a concentration of 0.0, 0.1, 0.2 and 0.4% (w/w). To avoid detrimental effects on carrageenan, all the experiments were performed at pH 7 at room temperature. The results showed that 0.2% w/w Alcalase® or Viscozyme® added individually achieved the highest protein extraction efficiencies (59 and 48%, respectively) at pH 7 and room temperature (p < 0.05). Determination of the most common carrageenan quality parameters indicated that using any of these enzymes had no negative effect on the carrageenan yield and quality.

Microalgae Nannochloropsis oceanica as a future new natural source of vitamin D3.

For the last two decades there has been a rise in awareness about the general low dietary intake of vitamin D3. Fish have the highest natural content of vitamin D3, which is suggested to originate from zooplankton and microalgae. However there are no studies reporting which microalgal species may be the source of vitamin D3. In this study, four selected microalgal species were cultivated during exposure of artificial UVB. The effect of UVB dose on the growth and biochemical composition of the cells (vitamin D3, PUFAs and carotenoids) was evaluated. Of the four species, exclusively Nannochloropsis oceanica was able to produce vitamin D3 (up to 1 ± 0.3 µg/g DM), and production was significantly enhanced by increasing the dose of the UVB. These findings suggest that N.oceanica exposed to artificial UVB could be used as a new natural source of vitamin D3, either as direct source or through animal feed.

Source, Extraction, Characterization, and Applications of Novel Antioxidants from Seaweed.

Driven by a general demand for clean labels on food and cosmetic products, these industries are currently searching for efficient natural antioxidants to replace synthetic antioxidants. Seaweed contains several compounds with antioxidative properties (phlorotannins, pigments, tocopherols, and polysaccharides). It is possible to extract these compounds via different extraction techniques, which are discussed in this review. Among the abovementioned compounds, phlorotannins are probably the most important in terms of the antioxidative potential of seaweed extracts. We review how the different antioxidative compounds can be characterized. We discuss the current knowledge of the relationship between phlorotannin's structure and antioxidant properties in in vitro studies as well as in food systems. Concerning food systems, most studies on the antioxidative effect of seaweed extracts have been performed with extracts prepared from Fucus vesiculosus, despite the fact that this species is less available than other species, such as Ascophyllum nodosum, which also has high phlorotannin content.

High-EPA Biomass from Nannochloropsis salina Cultivated in a Flat-Panel Photo-Bioreactor on a Process Water-Enriched Growth Medium.

Nannochloropsis salina was grown on a mixture of standard growth media and pre-gasified industrial process water representing effluent from a local biogas plant. The study aimed to investigate the effects of enriched growth media and cultivation time on nutritional composition of Nannochloropsis salina biomass, with a focus on eicosapentaenoic acid (EPA). Variations in fatty acid composition, lipids, protein, amino acids, tocopherols and pigments were studied and results compared to algae cultivated on F/2 media as reference. Mixed growth media and process water enhanced the nutritional quality of Nannochloropsis salina in laboratory scale when compared to algae cultivated in standard F/2 medium. Data from laboratory scale translated to the large scale using a 4000 L flat panel photo-bioreactor system. The algae growth rate in winter conditions in Denmark was slow, but results revealed that large-scale cultivation of Nannochloropsis salina at these conditions could improve the nutritional properties such as EPA, tocopherol, protein and carotenoids compared to laboratory-scale cultivated microalgae. EPA reached 44.2% ± 2.30% of total fatty acids, and α-tocopherol reached 431 ± 28 µg/g of biomass dry weight after 21 days of cultivation. Variations in chemical compositions of Nannochloropsis salina were studied during the course of cultivation. Nannochloropsis salina can be presented as a good candidate for winter time cultivation in Denmark. The resulting biomass is a rich source of EPA and also a good source of protein (amino acids), tocopherols and carotenoids for potential use in aquaculture feed industry.

Lipids and Composition of Fatty Acids of Saccharina latissima Cultivated Year-Round in Integrated Multi-Trophic Aquaculture.

This study is evaluating the seasonal lipid and fatty acid composition of the brown seaweed Saccharina latissima. Biomass was sampled throughout the year (bi-monthly) at the commercial cultivation site near a fish farm in an integrated multi-trophic aquaculture (IMTA) and at a reference site in Denmark (2013-2014). Generally, there was no difference in the biomass composition between sites; however, significant seasonal changes were found. The lipid concentration varied from 0.62%-0.88% dry weight (DW) in July to 3.33%-3.35% DW in November (p < 0.05) in both sites. The fatty acid composition in January was significantly different from all the other sampling months. The dissimilarities were mainly explained by changes in the relative abundance of 20:5n-3 (13.12%-33.35%), 14:0 (11.07%-29.37%) and 18:1n-9 (10.15%-16.94%). Polyunsaturated fatty acids (PUFA's) made up more than half of the fatty acids with a maximum in July (52.3%-54.0% fatty acid methyl esters; FAME). This including the most appreciated health beneficial PUFA's, eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), but also arachidonic (ARA) and stearidonic acid (SDA), which are not found in land vegetables such as cabbage and lettuce. Compared to fat (salmon) and lean fish (cod) this seaweed species contains higher proportions of ARA and SDA, but lower EPA (only cod) and DHA. Conclusively, the season of harvest is important for the choice of lipid quantity and quality, but the marine vegetables provide better sources of EPA, DHA and long-chain (LC)-PUFA's in general compared to traditional vegetables.

Life cycle assessment of biofuel production from brown seaweed in Nordic conditions.

The use of algae for biofuel production is expected to play an important role in securing energy supply in the next decades. A consequential life cycle assessment (LCA) and an energy analysis of seaweed-based biofuel production were carried out in Nordic conditions to document and improve the sustainability of the process. Two scenarios were analyzed for the brown seaweed (Laminaria digitata), namely, biogas production (scenario 1) and bioethanol+biogas production (scenario 2). Potential environmental impact categories under investigation were Global Warming, Acidification and Terrestrial Eutrophication. The production of seaweed was identified to be the most energy intensive step. Scenario 1 showed better performance compared to scenario 2 for all impact categories, partly because of the energy intensive bioethanol separation process and the consequently lower overall efficiency of the system. For improved environmental performance, focus should be on optimization of seaweed production, bioethanol distillation, and management of digestate on land.