Algae: What are the uses and the useful substances?

Algae – Whole plant – food!160 species of algae (Simpson) are used for food most coming from 3 genera (Porphyra, Laminaria, Undaria). Up to 75% of their dry bulk is indigestible.

uses of algae
  • Kelps (Kombu) vegetables in Japan and China
  • Porphyra (nori) north Pacific.
  • Nori – Japan since AD 533- 544; cultivation since 1623-49; when Japanese fishermen found bamboos pieces with it growing on them, and planted bamboo twigs into intertidal.
  • Cultivated for centuries in Japan, Korea and China. Value $1 billion per year Extension of nori season by spore refrigeration + production increase from 8 people making 1500 sheets per day to machines that to that work in an hours.
  • Porphyra toasted and used to wrap sushi
  • Ulva eaten as a green vegetable
  • Undaria (qundai-cai – China; wakame – Japan) enhances calcium uptake from gut, promotes bone formation Diatom fossils used to filter sugar cane liquors and as anticaking agents in dried foods.

Specific Chemical constituents of Algae

ALGINATES from Macrocystis pyrifera (USA) and other kelps, Ascophyllum nodosum (bladder wrack), Laminaria cloustoni (oar weed) and L. digitata in UK. L. digitata in Norway. Ecklonia and Durvillaea. Claim by Indians that Macrocyctis may weigh several hundred kilograms (check Bill Wheeler). Alginic acid industry started in Japan in 1923. Most still harvested from wild. China has cultivation of Laminaria for phycocolloids

Uses of Algae

  • Food industry – thickening agents (fruit drinks and salad dressing); emulsifiers (in salad dressings); colloid stabilizers in food (ice creams – stop ice crystal formation, sherbets and cheeses); adhesives for charcoal briquettes; suspending agents; beer clarifiers and foam stabilizers; filler in candy bars;. Metal alginates – cellophane like materials; canning of fruits; manufacture of artificial “foods” such as fake cherries, imitation caviar and reconstituted onion rings
  • Textiles;
  • Cosmetics (suspending agents);
  • Pharmaceutical (suspending agents);
  • Paint (they keep pigments suspended over a range of temperatures);
  • Paper (for sizing and polishing);
  • Welding industries;
  • Plastics (heavy metal salts);
  • Dental impressions gel materials;
  • Audio speakers : used to make fibers for high quality audio speakers

AGAR – first referred to in Japan (1658) called kanten (meaning cold sky) because it was traditionally produced during cold weather.
Red algae for agar (Gelidium amansii – Japan; Chondrus crispus (Irish Moss), Mastocarpus stellata, Gelidium pulchellum and G. latifolium – British Isles; Gelidium cartillagineum, G. arborescens and G. nudifrons – USA; Ahnfeltia plicata and Phyllophora nervosa – USSR; Frucillaria fastigiata – Denmark,. Also from Pterocladia and Acanthopeltis)

Supplies cut off from Japan during WW II, so allies had to find other sources. Commonest source now is Gelidium.

Agar’s first use discovered by Frau Franny Eilshemius (a physician’s wife) whose husband told Robert Koch, who is credited with the discovery!

  • Pharmaceutical capsules – for medication, dental impressions, cosmetic base,
  • Research and diagnostics – microbiological medium, biochemistry, electrophoresis,
  • Food – anti-drying agent in bakery goods; rapid-setting jellies and desserts in Europe, North America, Japan and China; temporary meat and fish preserved in tropics; thickening agent, emulsifier and stabilizer for sauces, soups, mayonnaise, cakes, beer cheese, ice creams and candies.

CARRAGEENAN Chondrus crispus and Gigartina mamillosa (very similar and also known as Irish Moss) for carrageenan. Gigartina undulata and Gigartina clavifera in New Zealand. Euchema cultivation improvements in Philippines since 1971 has seen production from 500 metric tons/y to 25,000 metric tons/y.

Algae are preferred over agar to stabilize emulsions in dairy products. Assists in suspension of cocoa particles in milk chocolate. Used in ice cream to prevent migration of colours in multi-coloured ices. Improves quality of soups, salad dressings, sauces, fruit drinks, etc.. Clarifying and stabilizing agent for beer. Known for a long time as a constituent of jellies, desserts, and milk puddings (blancmanges). Gelling, thickening and suspending properties are thermally reversible, or reversing states when solution is heated to a liquid and then cooled back to a gel. Very effective when is solution with proteinaceous materials. When added to hot milk, and cooled, bonds form between carrageenan and casein to give a creamy thick texture. This led to carrageenan replacing alginates for chocolate milk, yogurts, eggnog mixes and ice creams. Its high melting point makes it useful for making desserts in hot climates. It is immune to degradation by common enzymes (unlike cellulose gum).

It is used as a binder in toothpaste and also makes teeth shiny.

Preferred over agar to stabilize emulsions in paints, cosmetics and as a sizing agent in textile and leather industries.

Used in aqueous solution to suspend oil-based inks to allow them to be combed or swirled to create marbleized designs on paper and fabric.


Protein of the algae

Spirulina – a “blue-green” used for food in old (Lake Chad) and new world (Aztecs before conquistadores). Excellent protein supplement (72% of dry weight). 10 tons per acre (wheat – 0.16 ton per acre; cattle 0.16 ton per acre. A bit low in S- amino acids but superior to all plant protein sources and equal to meat or dairy products. Christopher Hills (UK) – dried alga for chicken feed with high protein and high carotene. Imperial Valley California and Kona coast of Hawaii using ponds in saline soil.


Vitamin C can equal citrus. Rich in vitamins A, D, B, B12, E, riboflavin, niacin, and pantothenic and folic acids


Undaria (qundai-cai – China; wakame – Japan) enhances calcium uptake from gut, promotes bone formation

Medical Uses of Algae

In the west mostly the phycocolloids from algae are used as binders and emulsifiers in pharmacy and in wound dressings (alginate wools are absorbent).

In the orient, widely used against parasites (Digenia used as a vermifuge: learned from watching dugongs eat this alga which is now known to contain kainic acid, a potent vermifuge), coughs, gout, goiter (Laminaria), venereal disease, even tumours. For childbirth, dried, sterile Laminaria stipes used to take up fluids, increase original circumference 3-5 times, and produce non-instrument mechanical dilation of the cervical canal during birth or gynecological treatment. Undaria (qundai-cai – China; wakame – Japan) enhances calcium uptake from gut, promotes bone formation

  • Anti-cancer – Sargassum sp., Codium pugniformis and Laminaria japonica extracts, Spirulina extracts inhibit growth of oral cancer cells. Phycocyanins have antitumour action and boost immune system. Maybe a B-carotene effect
  • The use of algae reduce cholesterol – Sterols in Spirulina, Chlorella and Scenedesmus lower cholesterol. Laminaria japonica administered for hypertension – effect may be related to iodine.
  • Appetite suppressant.
  • Spirulina is high in B vitamins, but >50g per day gives nausea unless tolerance acquired.
  • Anti-coagulant.
  • Laminaria digitata and Dilsea edulis (red) have anticoagulant effects – claimed for carrageenans.

Fertilizer and Soil Amendment

Anabaena sp. (blue green) are part of the “green manure” in their relationship with Azolla, an aquatic fern found in rice paddies. Inoculation of 0.2 kg of Azolla per hectare is equivalent to 30 kg/hectare of commercial nitrogen fertilizer. Not as popular now because we have found that Azolla growth is limited by phosphate, which is non-renewable. Next break is low-phosphorus requiring Azolla.

Many seaweeds are harvested for ash Na, K. Fertilizers generally rich in potassium and nitrogen but low in phosphate. Good complement to animal which is high in phosphate, equal in N and only 1/3 as rich in phosphate. Free of terrestrial weeds and fungi. Some liquid fertilizers, e.g. liquefied kelps marketed in BC by Wayne Temple and Reed Radley’s company.

Soil amendment. – Records as animal manure substitute since 5th century AD. Charles II allowed people to collect for fertilizer. Easement of an ox-cart’s width allowed and show in records of Rhode Island. Chlamydomonas and other soil algae make mucilage that loosen compacted soil. Used on compacted ash of Mt. St Helens to restore farming. Chlorella – only microscopic green used commercially, but I can’t find a product or a use. In Europe and N. Africa, calcareous algae useful to reduce soil acidity. algae uses

Industrial use of algae (not foods)

ALGINATES – colloid stabilizers in textile, cosmetic, pharmaceutical, paper and welding industries.

AGAR. – Agar’s first use as a microbiological medium discovered by Frau Franny Eilshemius (a physician’s wife) whose husband told Robert Koch, who is credited with the discovery! More recent uses include, dental impressions, cosmetic base, and biochemistry – electrophoresis chromatography support.

CARRAGEENAN – preferred over agar to stabilize emulsions in paints and cosmetics.

FOSSIL DIATOMS – (Bacillariophyceae Limestone – diatomaceous earth) USA produces 38%; also Russia, France and Denmark. Mined (open or underground). Dried from 60 to 5% water, ground and sorted. 68% of product used in filter aids, especially water purification. Used as flea killers, embalming compounds, enamel polishes. Diatomaceous bricks – Emperor Justinian order the dome of the church of Hagia Sophia in Istanbul in AD 532. Diatomite used to filter sewage in UK from 1976, to filter sugar cane liquors from 1914; Nobel used it to stabilize nitroglycerine. Used in match heads, to control cigar burning, to reduce glossiness in paint; fertilizers; anticaking agents in dried foods; pet litter – absorptive; on pet fur to render fur inhospitable to fleas


Details of waste treatment (see Simpson, page 641) . Tertiary treatment can use algal – bacterial culture + light + sewage leads to bio-oxidation. Produces precipitated organic material (sludge) plus oxygen which maintains aerobic bacteria. Organisms absorb N and P from sewage for their own use. With photosynthetic oxidation BOD drops 90% and P drops 80% . Get some examples (check Iona, but Simpson quotes Hollister, CA.).

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top