Agar-agar (also called agar, agal-agal, or kanten) is a natural gelling agent classified as food additive E406. It is extracted from red seaweed species (Phyllophora, Gracilaria, Gelidium, Ceramium, and others) or brown seaweed (Ahnfeltia, Furcellaria). Technologically, agar functions as a thickener, hydrocolloid, and gelling agent.
Chemical composition
Agar raw material contains approximately 1.5–4% mineral salts, 1–2% protein and nitrogenous substances, 10–20% water, and 70–80% carbohydrates (primarily polysaccharides). The polysaccharide fraction includes D- and L-galactose, 3,6-anhydrogalactose, pentoses, D-glucuronic acid, and pyruvic acid. Two key fractions — agarose (responsible for gelling) and agaropectin — can be extracted from agar.
Physical and chemical properties
Agar appears as a yellowish-white powder or flakes. Below 35–40 °C, it does not dissolve in water. Above 40 °C, it begins to swell and partially dissolve. At 90–100 °C, it dissolves completely. Upon cooling to 35–40 °C, the solution transforms into a firm, elastic gel. This thermoreversible behavior — dissolving when heated and gelling when cooled — is the foundation of all agar applications in food production.
Agar is one of the strongest gelling substances available. Its gel strength is measured in conventional units, with the most popular commercial grades being 900, 1000, and 1100. Unlike pectin and gelatin, agar begins to form a gel at concentrations as low as 0.3–0.5%. The required dosage depends on the agar grade, the presence of other ingredients that may strengthen or weaken its gelling action, and the desired final texture.
Applications in food production
Agar E406 is used in a wide range of food products:
- Jelly masses and fillings in confectionery production
- Imitation caviar manufacturing
- Instant soups
- Ice cream and desserts
- As a vegetarian and vegan replacement for animal-derived gelatin
Find more information about food additives and gelling agents in the articles below.