|Molar mass||10,000 - 600,000|
|Appearance||white to yellow, fibrous powder|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Alginic acid, also called algin or alginate, is an anionic polysaccharide distributed widely in the cell walls of brown algae, where through binding with water it forms a viscous gum. In extracted form it absorbs water quickly; it is capable of absorbing 200-300 times its own weight in water. Its colour ranges from white to yellowish-brown. It is sold in filamentous, granular or powdered forms.
Alginic acid is a linear copolymer with homopolymeric blocks of (1-4)-linked β-D-mannuronate (M) and its C-5 epimer α-L-guluronate (G) residues, respectively, covalently linked together in different sequences or blocks.
Commercial varieties of alginate are extracted from seaweed, including the giant kelp Macrocystis pyrifera, Ascophyllum nodosum, and various types of Laminaria. It is also produced by two bacterial genera Pseudomonas and Azotobacter, which played a major role in the unravelling of its biosynthesis pathway. Bacterial alginates are useful for the production of micro- or nanostructures suitable for medical applications.
Potassium alginate is a chemical compound that is the potassium salt of alginic acid. It is an extract of seaweed. Its empirical chemical formula is KC6H7O6.
Calcium alginate, made from sodium alginate from which the sodium salt has been removed and replaced with calcium, has the chemical formula C12H14CaO12.
Alginate absorbs water quickly, which makes it useful as an additive in dehydrated products such as slimming aids, and in the manufacture of paper and textiles. It is also used for waterproofing and fireproofing fabrics, as a gelling agent, and for thickening drinks, ice cream and cosmetics.
Alginate is used in various pharmaceutical preparations such as Gaviscon, Bisodol, and Asilone. Alginate is used extensively as an impression-making material in dentistry, prosthetics, lifecasting and occasionally for creating positives for small-scale casting. It is also used in the food industry, for thickening soups and jellies.
Calcium alginate is used in different types of medical products, including burn dressings that promote healing and can be removed with less pain than conventional dressings.
Due to its ability to absorb water quickly, alginate can be changed through a lyophilization process to a new structure that has the ability to expand. It is used in the weight loss industry as an appetite suppressant.
A major application for sodium alginate is in reactive dye printing, as thickener for reactive dyestuffs (such as the Procion cotton-reactive dyes) in textile screen-printing and carpet jet-printing. Alginates do not react with these dyes and wash out easily, unlike starch-based thickeners.
Sodium alginate is a good chelator for pulling radioactive substances from the body, such as iodine-131 and strontium-90, that have taken the place of their non-radioactive counterparts. It is also used in immobilizing enzymes by inclusion.
As a food additive, sodium alginate is used especially in the production of gel-like foods. For example, bakers' "Chellies" are often gelled alginate "jam." Also, the pimento stuffing in prepared cocktail olives is usually injected as a slurry at the same time that the stone is ejected; the slurry is subsequently set by immersing the olive in a solution of a calcium salt, which causes rapid gelation by electrostatic cross-linking. A similar process can be used to make "chunks" of everything from cat food through "reformed" ham or fish to "fruit" pieces for pies. It has the E-number 401.
Nowadays, it is also used in the biological experiments for the immobilization of cells to obtain important products like alcohols, organic acids, etc.
In recent years, sodium alginate has been used in molecular gastronomy. Ferran Adrià pioneered the technique, and it has since been used by chefs such as Grant Achatz and Heston Blumenthal. Sodium alginate is combined with calcium lactate or similar compounds to create spheres of liquid surrounded by a thin jelly membrane.
Its use as a pharmaceutical excipient is currently limited to experimental hydrogel systems. The viscosity, adhesiveness, elasticity, stiffness, and cohesiveness of potassium alginate hydrogels have been determined and compared with values from a range of other hydrogel-forming materials. The effect of calcium ions on the rheological properties of procyanidin hydrogels containing potassium alginate and intended for oral administration has also been investigated.
Hyaluronic acid: a similar polysaccharide in animals.
- Raymond C. Rowe, Paul J. Sheskey, Marian E. Quinn, ed. (2009), "Adipic Acid", Handbook of Pharmaceutical Excipients (Rowe, Handbook of Pharmaceutical Excipients) (Sixth ed.), Pharmaceutical Pr, pp. 11–12, ISBN 0-85369-792-2
- Remminghorst and Rehm (2009). "Microbial Production of Alginate: Biosynthesis and Applications". Microbial Production of Biopolymers and Polymer Precursors. Caister Academic Press. ISBN 978-1-904455-36-3.
- "Lo Mejor de la Gastronomia". StarChefs.com. Archived from the original on 1 December 2007. Retrieved 2007-11-14.
- "Seaweed to tackle rising tide of obesity". Newcastle University. Archived from the original on 25 March 2010. Retrieved 2010-03-22.
- Sutton, A., Harrison, G. E., Carr, T. E., and Barltrop, D. Reduction in the absorption of dietary strontium in children by an alginate derivative. Br.J.Radiol. 44, 567. 1971
- Sutton, A., Harrison, B. E., Carr, T. E., and Barltrop, D. Reduction in the absorption of dietary strontium in children by an alginate derivative. Int.J.Radiat.Biol.Relat Stud.Phys.Chem.Med. 19, 79-85. 1971
- More details about Alginate. Alginate manufacturer KIMICA
- Alginate seaweed sources
- Alginate properties
- article Wired on Easy Cheese, describing sodium alginate