Seaweeds, Greens, Browns & Reds

Seaweed Classification Seaweeds may look similar to plants but their biology is very different and they inhabit the Kingdom of the Protista, neither plants nor animals. Some algae are tiny single cells, microalgae, growing in fresh water. Others are marine species eg the cyanobacteria usually known as blue green algae. All the microalgaes are extensively cultivated commercially around the world.. There are three main types of macroalgae, which are the large marine algaes or seaweeds that we can classify by pigment. Green Algae - Chlorophyta, Brown Algae - Phaeophyta and Red Algae - Rhodophyta

Green algae: Chlorophyta Green Algae – Enteromorpha compressa (green laver) , Ulva (sea lettuce) and Monostroma highly prized for food in Far East and grown commercially. In Ireland Codium Fragile(Sponge Weed), is used as invertebrate food by the mariculture industry, is a pest of natural and cultivated shellfish beds, and is a source of bioactive compounds (Trowbridge 1999; WGITMO 2001). Cladophora rupestris is used as an additive for chicken food to enhance the yolk colour and meat quality.	Rory MacPhee Castle Beach 2009
Green seaweeds also contain various medical compounds used for such conditions as anticoagulation of blood, lowering of plasma cholesterol, tonics for liver function, treatment of ulcers and sources of omega 3.

Hazel Tompkins Lizard 2009	Brown algae: Phaeophyta Brown seaweeds (include genera macrocystis and nerocystis) - like cool water below 16°C , (which is the temperature of water around this coast most of the time). Very good source of iodine and the most commonly used species for alginates. Grown commercially in Japan, Korea. China, Russia, Indonesia, East Africa, N. America and Europe. Alginates from the macroalgaes such as the Laminaria (kelp) family are also used as thickeners in lots of products from salad dressings to oil-drilling muds and fluids to coatings for welding rods and in paper manufacture. Undaria – another brown kelp which likes cooler waters is eaten dry, semi dry and roasted in the Far East.
	Alginic acid, also called algin or alginate, is a viscous gum that is abundant in the cell walls of brown algae. It ranges from white to yellowish-brown, and takes filamentous, granular and powdered forms. It absorbs water quickly; it is capable of absorbing 200-300 times its own weight in water.

Red algae: Rhodophyta The Division Rhodophyta has the most species of algae, both simple forms and highly branched filaments, fleshy and flat sheets. The Red seaweeds have a rubbery, stretchy quality formed by their unique intercellular structure. They contain the pigments phycocyanin and phycoerythrin in addition to chlorophyll, these pigments allow them to grow at much deeper depths and absorb light from the shorter blue wavelengths. Sometimes the colours of the Red Algae varies and they can appear purple, brown, green or yellow. The cell walls of the Rhodophyta species contain agar and carrageenan. Agar or agar agar is a gelatinous substance used for culture mediums in microbiological work, biotechnology, criminology, and as a gelling compound in food products, besides many other commercial uses. Primarily from the genera Gelidium and Gracilaria, or seaweed (Sphaerococcus euchema). There are three main commercial classes of carrageenan: Kappa: strong, rigid gels. Gels with potassium ions, reacts with dairy proteins. Mainly from Eucheuma cottonii. Iota: soft gels. Gels with calcium ions. Produced mainly from Eucheuma spinosum Lambda: Does not gel, used to thicken dairy products. The most common source is Gigartina from South America. Carrageenan is added to toothpastes, dairy products, yoghurts and ice creams to name just a few. Red seaweeds also include the species Porphyra Umbilicus which is possibly the highest valued commercial marine resource. Extensively eaten in Japan and the Far East (Nori) and now farmed in many locations globally. In Europe this seaweed is known as Laverbread, Sloke and Bara Lawr. Last but not least at the coralline algae which contain magnesium and calcium carbonate in their cell walls. The seaweeds are hard and brittle and were previously thought to be corals. Medical science now uses corallines in the preparation of dental bone implants. The cell fusions provide the matrix for the regeneration of bone tissue. Maerl is also used in agriculture as a soil conditioner and fertilizer, and as an additive for cattle feeds but extraction may not be sustainable given the very slow growth periods. Andrea Sinclair, Swanpool Beach 2009	Crissy Haydon Kennick Sands 2009
	Agar (agar agar) can be used as a laxative, a vegetarian gelatin substitute, a thickener for soups, in jellies, ice cream and Japanese desserts such as anmitsu, as a clarifying agent in brewing, and for paper sizing fabrics. Chemically, agar is a polymer made up of subunits of the sugar galactose. Agar polysaccharides serve as the primary structural support for the algae's cell walls. (Wikipedia) Carrageenans are large, highly flexible molecules which curl forming helical structures. This gives them the ability to form a variety of different gels at room temperature. They are widely used in the food and other industries as thickening and stabilizing agents. A particular advantage is that they are pseudoplastic—they thin under shear stress and recover their viscosity once the stress is removed. This means that they are easy to pump but stiffen again afterwards. Many red algal species produce different types of carrageenans during their developmental history. For instance, the genus Gigartina produces mainly Kappa carrageenans during its gametophytic stage, and Lambda carrageenans during its sporophytic stage. See Alternation of generations. All are soluble in hot water, but in cold water only the Lambda form (and the sodium salts of the other two) are soluble. When used in food products, carrageenan has the EU additive E-number E407 or E407a when present as "Processed eucheuma seaweed".

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