Potential scale of Scottish seaweed-based industries: research paper

B Seaweed Products and Uses

B.1 Overview of seaweed products and uses

B.1.1 This appendix provides an overview of the types of products obtained from seaweeds and the basis of the product groupings used within this study. For further information regarding the uses of seaweeds readers are directed to Cefas (2016) and Stanley et al. (2019).

B.1.2 Seaweeds can be used as a raw material for several end uses including human foods, animal feed, horticulture and fertiliser, hydrocolloids, bioactives used in the nutraceuticals, pharmaceuticals and cosmeceuticals industries, and biofuels (Stanley et al., 2019). There are also wider applications for seaweeds in bioremediation and integrated multi-trophic aquaculture (IMTA), as well as knowledge industries associated with the production of seaweeds and development of products.

Human food

B.1.3 Seaweeds can be used in a broad variety of formats (e.g. fresh, dried, powder or flakes, salted, canned, liquid extracts or as prepared foods) and used in human foods for direct human consumption (McHugh, 2003; Bixler & Porse, 2011; Anis et al., 2017). The use of seaweeds in foods and traditional cuisine is popular in Asian countries. The main types of seaweed used as food are Laminaria spp., Undaria spp., Hizikia spp., Porphyra spp. (nori or laver), Palmaria palmata, Ulva spp. and Monostroma spp. (Cefas, 2016). The markets in Europe and North America are less well-developed but are beginning to increase (Stanley et al., 2019). There is an increasing body of evidence that the consumption of algal food products may have health and nutritional benefits, though the nutritional composition and bioavailability and digestibility of macroalgae compounds is not fully understood (Buschmann et al., 2017; Wells et al., 2016). Care is also required around food safety standards if seaweeds are to be consumed in high amounts due to potential for adverse health effects (for example from potentially high metal and iodine concentrations) (Stanley et al., 2019).

Animal feed

B.1.4 Seaweeds have been used for a long time as animal feed, particular for sheep, cows, pigs, horses (on the Orkney Islands, Scotland, there is a native breed of sheep feeding on seaweed on the shore) (Cefas, 2016). Commercially, seaweeds are added to animal feed as a supplement in the form of granules or powder, the amount of which is regulated under European legislation (Stanley et al., 2019). Ascophyllum nodosum, Alaria spp., Laminaria spp., Palmaria spp. and Ulva spp. are species commonly added to fodder after it is dried and milled, and is marketed as improving health, fertility and overall productivity of livestock (Stanley et al., 2019). Seaweed is also added as feed in either fresh or dried form in aquaculture, for example in abalone farming (note, not in Scotland) using Ulva and Fucus spp. (Bansemer et al., 2016; Stanley et al., 2019). Recent research has focussed on the potential to use red seaweed (Asparagopsis taxiformis naturally occurring in tropical/subtropical oceans), as a supplement within cattle feed to reduce the methane emissions from cattle (Roque et al 2019, 2021). A recent feasibility study in the UK has been undertaken to identify species of seaweeds that are found in the UK with similar potential for methane suppression^[44].

Horticulture

B.1.5 Seaweeds can be used in horticulture as a fertiliser to encourage plant growth by providing a source of micronutrients (Cefas, 2016). This is usually applied in liquid form, whereby seaweeds are heated and pressurised to extract nutrients, though dried seaweed can also be used. Dried seaweed can also be applied as a soil conditioner to allow greater water and air penetration (Mouritsen, 2013).

Hydrocolloids

B.1.6 Hydrocolloids are polymers used mainly in food products, but also in cosmetic and medical products (Cefas, 2016). They bind to water and form viscous dispersions or gels which are then used as additives and stabilisers across these sectors (Mouritsen, 2013). Three types of hydrocolloids can be extracted from seaweeds: alginates, which are extracted from brown seaweed (alginophytes); agar, which are extracted from red seaweed (agarophytes); and carrageenan which are also extracted from types of red macroalgae (carrageens).

Bioactives

B.1.7 Extracts from seaweeds have applications in health and personal care, and can be referred to as bioactives where they have a biological effect and promote good health. Examples of these products include the polysaccharides laminarin (extracted from brown algae) which have anti-bacterial properties (Anis et al., 2017), and fucoidans which have anti-viral properties (Hayashi et al., 2008). Other research suggests other bioactive compounds found in seaweeds have the potential to interact with cancers, the immune system, inflammation and pathogenic fungi (Cefas, 2016 and references cited therein). Hydrocolloids (described above) can also be used for medical purposes such as capsules for medicines, and making plasters or bandages (Cefas, 2016). Nutraceuticals can also be produced from seaweeds to improve heath. These are dietary supplements that contain the beneficial vitamins, minerals and essential trace elements, polyunsaturated fatty acids, bioactive metabolites, proteins, polysaccharides and dietary fibres contained within seaweeds (Ganesan et al., 2019). Seaweeds can also be incorporated into cosmetic products and range from simple dried seaweeds for home baths to high value spa and cosmetics ranges (Stanley et al., 2019). Much of the evidence for the efficacy of these cosmetic products is anecdotal, but research into bioactive compounds contained in seaweeds substantiates their use in cosmetics (Stanley et al., 2019).

Biofuels

B.1.8 There has been considerable interest in the use of seaweed as a feedstock to produce biofuels. Kelps in particular, have been the focus of considerable interest due to advantages over traditional biomass for biofuels such high productivity, fast growth rates, and the fact they do not need land or freshwater to grow (reflected in the large number of funded research projects on algal biofuel technologies such as SeaGas) (Cefas, 2016). However, seaweed-based biofuels still face issues such as scalability and economic viability, and competitiveness and performance against other feed stocks need to be considered (Bruton et al., 2009; SARF, 2016; Stanley et al., 2019).

Bioremediation

B.1.9 Alongside extractive seaweed industries and products, seaweeds can be used for bioremediation purposes. As efficient absorbers of nutrients and contaminants, seaweeds can remove waste released from aquaculture installations (Cefas, 2016). This is often employed in aquaculture facilities to reduce pollution.

Biotechnology

B.1.10 There are other novel and innovative applications for seaweed that have not yet been taken up on a large scale and remain in development. This includes using seaweed as raw material (feedstock) for biotechnology processes, such as biorefining to extract a range of products (with a range of values) from the whole seaweed plant, and/or the production of biomaterials (such as bioplastic) to create alternative packaging materials. A biorefinery approach to seaweed production has been described by Cefas (2016), Stanley et al. (2019) and BIM (2020). It integrates a chain of production for different fuels and products to extract a range of high and low value products and optimises the processing of seaweed to improve production economics (Stanley et al., 2019). This process allows access to different markets and reduces waste, thereby making production more viable (Cefas, 2016). This feeds directly into the concept of bio and circular economies which is advocated by some seaweed-related stakeholders and businesses already established in the UK.

B.1.11 The biorefinery approach extracts the most valuable components from algal biomass, leaving the remainder unadulterated for commodity purposes (food, feed, fertiliser, fuel) (Baghel et al, 2015; Trivedi et al, 2015 in Buschmann et al, 2017). As shown in Figure B1, production of fuels, energy, and animal feed require large volumes of seaweed but the price for the biomass is small around < £1 per kg. However, when algal components are used in high-value products, such as nutraceuticals and cosmeceuticals, the value of algae derived product becomes substantially higher at > £2,000 per kg, and up to > £5,000/kg for special applications (Cefas, 2016). In the UK, the current capacity for seaweed production sits between 'added value commodities' and 'speciality products' (Cefas, 2016).

B.1.12 The biorefinery approach may be an important concept for the future of the global seaweed industry, including Scotland. However, there are knowledge gaps in its application, encompassing biological and engineering challenges, bioprocessing technologies, environmental implications, sustainability issues, and policy and legislation hurdles (Stanley et al., 2019).

Source: Cefas (2016)

B.1.13 The categories of seaweed-based products used within the main report are summarised in Table B1. Some of these categories overlap by virtue of their eventual end uses. For example, hydrocolloids are used in both human food products and pharmaceuticals and other personal care products. Equally, nutraceuticals might be considered as human food as products are ingested as a dietary supplement, although for the purposes of this study, they have been considered within the bioactive category. Table B1 also indicates which product categories were included within the socio-economic evaluation in the main report.

Table B1. Product categories for seaweed uses

Product category	Description	Scoped into the socioeconomic evaluation
Human food	Seaweed products that are intended for human consumption	Yes
Animal feed	Seaweed products that are incorporated into animal feed	Yes
Horticulture	Seaweed products to aid plant cultivation such as fertiliser and soil conditioners	Yes
Bioactives (cosmetics, pharmaceuticals, and nutraceuticals)	Seaweed products for use in personal care and health applications (cosmetics, pharmaceuticals, and nutraceuticals)	Yes
Hydrocolloids	Seaweed extracts such as alginates, agar, carrageenan	Yes
Biotechnology	Using seaweed as a feedstock for biotechnology processes that extract a range of high value products or novel products	Yes
Biofuels	The use of seaweed to produce energy and fuels	No
Bioremediation	The use of seaweed to remove nutrients and contaminants from water to improve water quality	No

B.2 References

Anis, M., Ahmed, S. & Hasan, M., 2017. Algae as nutrition, medicine and cosmetic: the forgotten history, present status and future trend. World Journal of Pharmacy and Pharmaceutical Sciences, 6: 1934–1959.

Baghel, R.R.S., Trivedi, N., Gupta, V., Neori, A., Reddy, C.R.K., Lali, A. & Jha, B., 2015. Biorefining of marine macroalgal biomass for production of biofuel and commodity chemicals. Green Chemistry, 17: 2436–2443.

Bansemer, M.S., Qin, J.G., Harris, J.O., Duong, D.N., Hoang, T.H., Howarth, G.S. & Stone, D.A., 2016. Growth and feed utilisation of greenlip abalone (Haliotis laevigata) fed nutrient enriched macroalgae. Aquaculture, 452: 62-68.

BIM, 2020. Scoping a seaweed biorefinery concept for Ireland. Report for Bord lascaigh Mhara. May 2020.

Bixler, H.H.J. and Porse, H., 2011. A decade of change in the seaweed hydrocolloids industry. Journal of Applied Phycology, 23: 321–335.

Bruton, T., Lyons, H., Lerat, Y., Stanley, M. & Rasmussen, M.B., 2009. A Review of the Potential of Marine Algae as a Source of Biofuel in Ireland. Sustainable Energy Ireland. pp. 88.

Buschmann, A.H., Camus, C., Infante, J., Neori, A., Israel, Á., Hernández-González, M.C., Pereda, S.V., Gomez-Pinchetti, J.L., Golberg, A., Tadmor-Shalev, N. and Critchley, A.T., 2017. Seaweed production: overview of the global state of exploitation, farming and emerging research activity. European Journal of Phycology, 52(4), pp.391-406

Cefas, 2016. Seaweed in the UK and abroad – status, products, limitations, gaps and Cefas role. [Online] Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/546679/FC002I__Cefas_Seaweed_industry_report_2016_Capuzzo_and_McKie.pdf (accessed May 2020).

Ganesan, A.R., Tiwari, U. and Rajauria, G., 2019. Seaweed nutraceuticals and their therapeutic role in disease prevention. Food Science and Human Wellness.

Hayashi, K., Nakano T., Hashimoto M., Kanekiyo K., Hayashi T. 2008. Defensive effects of a fucoidan from brown alga Undaria pinnatifida against herpes simplex virus infection. International Immunopharmacology 8(1): 109-116.

McHugh, D.J., 2003. Seaweeds uses as human foods. In A Guide to the Seaweed Industry. FAO Fisheries Technical Paper 441. FAO, Rome.

Mouritsen, O. G., 2013. Seaweeds edible, available and sustainable. The University of Chicago Press, Chicago and London; pp. 287.

Roque, B.M., Brooke, C.G., Ladau, J., Polley, T., Marsh, L.J., Najafi, N., Pandey, P., Singh, L., Kinley, R., Salwen, J.K., Eloe-Fadrosh, E., Kebreab, E., Hess, M. 2019. Effect of the macroalgae Asparagopsis taxiformis on methane production and rumen microbiome assemblage. Animal Microbiome (2019) 1:3. https://doi.org/10.1186/s42523-019-0004-4.

Roque, B.M., Venegas, M., Kinley, R.D., de Nys, R., Duarte, T.L., Yang, X., Kebreab, E. 2021. Red seaweed (Asparagopsis taxiformis) supplementation reduces enteric methane by over 80 percent in beef steers. PLoS ONE 16(3):e0247820. https://doi.org/10.1371/journal.pone.0247820

Scottish Aquaculture Research Forum (SARF) 2016. A risk benefit analysis of mariculture as a means to reduce the impacts of terrestrial production of food and energy. A report by ABPmer and the University of Stirling for SARF and WWF-UK. Report R.4269.

Stanley, M.S., Kerrison, P.K., Macleod, A.M., Rolin, C., Farley, I., Parker, A., Billing, S-L., Burrows, M. & Allen, C., 2019. Seaweed Farming Feasibility Study for Argyll & Bute. A report by SRSL for Argyll & Bute Council. pp. 190.

Trivedi, J., Aila, M., Bangwal, D.D.P., Kaul, S. & Garg, M. O., 2015. Algae based biorefinery – how to make sense? Renewable and Sustainable Energy Reviews, 47: 295–307.

Wells, M.M.L., Potin, P., Craigie, J.S., Raven, J.A., Merchant, S.S., Helliwell, K.E., Smith, A.G., Camire, M.E. & Brawley, S.H. (2016). Algae as nutritional and functional food sources: revisiting our understanding. Journal of Applied Phycology, 29: 949–982.