Many commercial products having great economic value are derived from the cell walls of algae. Some of them are:
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Agar: It is a polymer of galactose having sulfate groups. It is obtained from red algae. Species of Gelidium and Gracilaria are used extensively. It is used as a solidifying agent in the preparation of microbiological media. In the food industry, it is used in the manufacture of jellies, processed cheese, puddings. In pharmaceutical industry, it is used as a carrier molecule for a drug. It is also found is ointments and lotions.
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Carrageenan: It is extracted from the wall of red algae. The most frequently used species are Gigartina, Eucheuma and Chondrus. It is used as an emulsifying agent in ice creams and other milk products. It is also used as a finishing compound in paper and textile industry, as a thickening agent in shaving creams and in the soap industry. It is also useful as a binding agent in toothpastes and in pharmaceutical products.
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Alginic acid: It is obtained from the walls of brown algae. The species of brown algae used to obtain this compound are Agarum, Macrocystis, Laminaria, Fucus and Ascophyllum. It is used in the preparation of ice creams as it provides a smooth consistency and eliminates the formation of ice crystals. They are incorporated into cheese and bakery products. Its other industrial applications include paper manufacturing, thickening of paints and fabric printing. Alginate material is also used by dentists to take impressions of the teeth for crowns.
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Diatomaceous earth: It is the fossilized remains of the cell wall of diatoms. It is used as filters. It is also used for polishing delicate surfaces.
ALAGE AS FOOD:
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Many species of red and brown algae are used as food in the Far East. Porphyra (Red algae) is used as food in Japan where is it known as “Nori” and is processed into dried sheets.
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Other species of algae such as Chondrus, Eucheuma, Nemalion and Acanthopeltis are eaten as vegetables or in soups or prepared as sweetened jellies.
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Porphyra, Gracilaria and Chondrus are extensively used in Europe, North America and China.
