Alginates are salts of alginic acid, or more simply algin, a polymer obtained from the cell wall of various algae, among which laminaria ( Laminaria spp. ) And fucus ( Fucus vesiculosus and Fucus serratus ) stand out for notoriety .
Alginic acid is a linear anionic polymer of D-mannuronic acid and L-glucuronic acid, held together by Β1-4 bonds. The proportion between these two acids varies according to the plant sources from which it is extracted, directly influencing their properties: alginates rich in D-mannuronic acid form soft and flexible gels, while those rich in L-glucuronic acid form more compact and resistant gels. .
Uses in the kitchen
In common language, therefore, the term alginates includes alginic acid (E400) and the relative salts, such as sodium (E401), calcium (E404), potassium (E402) and ammonium (E403).
The dietary-health applications of alginates are quite varied, but shared by precise functional characteristics.
In contact with water, alginates absorb it in quantities tens of times higher than their own weight . In the food industry this adsorbent property makes them widely used as ” thickeners “, to enhance the consistency of jams, marmalades, ice creams, sweets, melted cheeses and spreads. Although alginates are considered safe additives , their use can indicate a lack of quality in the choice of raw materials or in the production process.
Still in the food sector, alginates are used as a base for low-calorie foods, given their ability to absorb water and form viscous gels, rather satiating but low in calories .
In fact, alginates are similar to soluble fibers , and as such they can be used as mass mechanical laxatives (the swelling of the fecal material stimulates peristalsis ); in both cases they must necessarily be accompanied by abundant quantities of water.
The viscous colloidal solutions formed by alginates in contact with water are also used by official medicine to hinder gastroesophageal reflux , and protect the mucous membrane of the stomach in the presence of gastritis or mild peptic ulcers ; often the use of alginates in this context occurs in synergy with antacid drugs .