Sodium alginate

Sodium alginate is a linear polysaccharide and a copolymer made from a brown seaweed that is a cheap and available biopolymer. This material is considered due to its biodegradability, hydrophilic properties, PH sensitivity and natural nature and is soluble in water and when dissolved, a liquid with viscosity is obtained.
Sodium alginate (sodium salt of alginic acid) is a type of gum that is obtained from a seaweed and is soluble in hot and cold water and is used to make gels in a variety of sauces, dessert gel and puddings, etc. this gum reacts with calcium salts or acid to from irreversible gels. It also has firming and binding properties and is used as an edible wrapper in some processed foods.
In industrial scale, sodium alginate gels have been used due to their properties such as viscosity, material stabilization properties and water retention ability, and in recent years have been used for biotechnology, medical, pharmaceutical and especially food industry applications.
Sodium alginate is more commonly used than empty alginate because acidic alginate is harmful to tissues and cells. Because alginate hydrogels are formed at low temperatures and PH, they are suitable for use with molecules such as proteins and nucleic acids, and even living cells. Alginate gels are unstable in the presence of chelating cation such as citrate, lactate, phosphate, tartrate, sodium and potassium cations, which are present in most biotechnological fluids. Polymers such as chitosan and poly alginate are added to calcium gels to prevent excessive swelling of alginate gels. 
Sodium alginate has the ability to form gels, increase tissue strength, stabilize and film. When a thin layer of gel or sodium alginate solution dries, it leads to the formation of film or coatings that can maintain water holding capacity, protect against microbial spoilage, resistance to oxidation, and so on.