Sodium Alginate

 

Sodium Alginate, also known as algin or alginic acid sodium salt, is a naturally occurring anionic polysaccharide. It is primarily extracted from the cell walls of brown algae (such as kelp and giant kelp) and is one of the most abundant structural components in seaweed. Its molecules are composed of two monomers, β-D-mannuronic acid and α-L-guluronic acid, linked by 1,4-glycosidic bonds.

Molecular formula: (C6H7O6Na)n

CAS NO.: 9005-38-3

 

 

Many applications of alginate are based on the following key characteristics

 

Gel-forming ability: This is its most important property. When an alginate solution comes into contact with divalent cations (most commonly calcium ions Ca²⁺), rapid ionic cross-linking occurs, forming a thermally irreversible gel with a three-dimensional network structure. This process is mild, fast, and typically occurs at room temperature.

 

Thickening and stabilizing effects: As a hydrophilic colloid, it can significantly increase the viscosity of aqueous solutions and act as an emulsifying and foam stabilizer.

 

Film-forming ability: It can form flexible, transparent films.

 

Biocompatibility and safety: It is non-toxic, biodegradable, and generally recognized as safe (GRAS), widely used in food and pharmaceutical fields.

 

PH sensitivity: In acidic conditions (low pH), alginate undergoes protonation, increasing viscosity or even precipitating; it remains stable under alkaline conditions.

 

 

Food Industry (Commonly used as food additive E401)

• Gelled Foods: Production of artificial jellyfish, dessert gels, and spherification products (e.g., "flavor bursts" or "caviar" in molecular gastronomy).
• Thickening & Stabilizing Agent: Used in ice cream (to inhibit ice crystal growth), yogurt, sauces, and dressings to improve texture and stability.
• Water Retention Agent: Added to bread and pasta to retain moisture and extend shelf life.

 

Pharmaceuticals & Biotechnology

• Wound Dressings: Calcium alginate dressings absorb wound exudate and form a soft, moist gel that promotes healing and allows for non-traumatic removal.
• Drug Delivery: Widely used as a matrix for controlled-release drug delivery, particularly for colon-targeted delivery due to its stability in gastric acid and solubility in intestinal fluid.
• Cell Encapsulation & Tissue Engineering: Its mild, ion-induced gelation is ideal for entrapping live cells, proteins, or drugs. It is a key material for bioinks in 3D bioprinting and tissue scaffolds.

 

Other Industrial Uses

• Textile Printing: Serves as a thickener in fabric printing pastes.
• Personal Care & Cosmetics: Used in toothpaste, facial masks, and creams as a gelling and stabilizing agent.
• Environmental: Utilized as an adsorbent for heavy metal ions in wastewater treatment.

 

 

Sodium alginate	Mesh	Viscosity	Standard	Application
Industrial grade	30-200mesh	1% 10-4000cps	SC/T3401-2006	Dying, Welding, Water treatment
Food grade	30-200mesh	1% 10-40000cps	GB1886.243-2016	Meat product, Bionic food, Bakery, milk products, beverage
Pharmaceutical grade	30-200mesh	10% 300-700cps	CP2015/EP9.0/USP40/BP	Coating, Oral suspension
		1% 10-1500cps		Medical dressing