Seaweed in Ireland
Marine microalgae or seaweeds, are plant-like organisms that generally live attached to rock or other hard substrata in coastal areas. They can be divided into three main groups based on their pigmentation: brown algae, green algae, and red algae.
Ireland has a long history of seaweed use, which continues to the present day. Approximately 40,000 tonnes of seaweed is harvested in Ireland each year with over 95 per cent naturally grown. Seaweed is rich in vitamins and minerals and is a source of protein and fibre. Seaweed can be used in many dishes including sushi rolls, breads, stews, salads, soups as well as smoothies.
Harvesting of seaweed can be carried out in many ways, such as by hand (using handheld tools) as well as mechanically. Cultivated seaweed refers to the cultivation or farming of seaweed, which can be done in tanks on land, or at sea. Cultivated seaweed is usually grown on ropes but can also be grown on other substrates.
The trend today is to refer to marine algae as ‘sea-vegetables’, when used as food, and what follows are some of the more common ones:
Some of the most well-known sea-vegetables available in Ireland are dulse and carrageen moss. Dulse - also known as dillisk (Palmaria palmate) belongs to the red algae (Rhodophyta) group. It is generally only eaten in Ireland after it has been dried. Carrageen Moss or Irish Moss (Chondrus crispus) is widely sold dried for cooking. This is a smaller weed, which is red, brown or purple in colour and also belongs to the red algae (Rhodophyta) group.
All Irish kelp species are edible but sugar kelp (Saccharina latissimia) is the most palatable and cooks well. It can be green or brown-red, with a long ruffled like blade and belongs to the brown algae (Phaeophyta) group.
Two other brown algae with potential as food are sea spaghetti and dabberlocks (or murlins). Himanthalia elongata, commonly known as sea spaghetti is recognised by its green-brown long thong-like fronds, with a button-like base. Sea spaghetti is sold in Ireland dried. After soaking in water, it can be used in mixed salads and does not have a strong seaweedy taste. Dabberlocks or murlins (Alaria esculenta) is a seaweed with a yellow-brown frond attached by a root-like holdfast at the base. For further information, please consult www.seaweed.ie
Seaweed has a high protein content – red seaweed generally has the highest protein content with approximately 20-30 % of dry weight as protein, with up to 47% in some species such as dulse (dillisk). Green algae generally comprise 9-26 % protein and brown algae contains between 3-15% protein, with some species reported as being in excess of that.
Seaweeds have a high carbohydrate concentration with complex polysaccharides and fibre. The carbohydrates identified in seaweed include several different types of polysaccharides e.g. sulphated galactans such as agar and carrageenans; and sulfated fucans also simply known as fucans, which are mainly found in species of brown algae.
Seaweeds have a relatively low fat content, however they do contain oils similar to those found in fish. Algal oils (from macro and microalgae), are sources of the long chain polyunsaturated fatty acids (LC-PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
The habitat of seaweeds varies from species to species but many of them spend large amounts of time exposed to direct sunlight in an aqueous environment. As a result, seaweeds contain many forms of antioxidants, including vitamins and protective pigments. Seaweeds contain both water- and fat-soluble vitamins. These include vitamins A, B, C, and E.
Seaweed contains important minerals such as calcium, sodium, potassium, iron, iodine and copper. For example, an 8 g serving of dry dulse (dillisk) contains 6.4mg of iron. According to the HSE, the recommended daily intake of iron per day is 14.8mg for women and 8.7mg for men.
Due to the nature of the compounds available in seaweeds, many seaweeds may have associated health benefits including anti-viral properties; antioxidants as well as possible benefits to heart and gut health.
Cliodhna Ní Ghriofa, Project Officer, SW Grow, Údarás na Gaeltachta.
Dáíl Eireann https://www.oireachtas.ie/en/debates/debate/dail/2018-03-07/16/ Accessed 30/04/20.
MacArtain, P., Gill,C.I.R, Brooks, C., Campbell, R., Rowland, I.R, (2007) Nutritional Value of Edible Seaweeds. Nutrition Reviews, Volume 65, Issue 12, Pages 535–543.
Troy D.J, Tiwari B, Hayes M, Ross P, Stanton C, Johnson M, Stengel D, O’Doherty JV, FitzGerald RJ, McSorley E, Kerry J. (2017) Marine Functional Foods Research Initiative (NutraMara) Project-based Award. Marine institute.