Alginaatit

Alginaatit are salts of alginic acid, a natural polysaccharide obtained from brown seaweeds (Phaeophyceae), especially species such as Laminaria and Macrocystis. They are produced commercially as sodium alginate and other alginates (e.g., calcium, potassium alginate) and are used as thickening, gelling, and stabilizing agents in various industries.

Chemically, alginates are linear copolymers made up of two uronic acids: β-D-mannuronic acid (M) and α-L-guluronic acid (G). The arrangement and ratio of M and G blocks govern gelling behavior. In water, sodium alginate is soluble; in the presence of divalent cations such as calcium (Ca2+), it crosslinks to form calcium alginate gels. The gel strength and texture depend on the M/G composition and crosslinking conditions. Gels can be reversible or partially irreversible, influenced by ion type, concentration, and pH.

Applications are diverse. In the food industry, alginaatit serve as thickeners, stabilizers, and gelling agents in dairy products, dressings, and canned foods, and as dietary fibers. In dentistry, alginate impressions (irreversible hydrocolloids) are used to record dental arches. In medicine and wound care, alginate dressings create a moist environment and can absorb exudate. In pharmaceuticals and biotechnology, alginates act as excipients, gel beads for immobilization, and components in controlled-release systems. They are also used in research and materials science for gels, films, and separation media.

Extraction and regulation: Alginate is extracted from seaweed through alkaline treatment and processed into sodium, calcium, or other salts. Many jurisdictions regulate alginates as safe food additives (E400) and for specific medical or cosmetic uses.