Uses of Sodium Alginate in Many Fields – Properties – Application

Have you ever known about Sodium Alginate and its uses in our life? Before we discuss about Sodium Alginate, it is better for us to know about the Alginate first.

Alginate is a fikokoloid or hydrocolloid extracted from phaeophyceae (brown algae). This compound is heteropolysaccharide from the formation of monomeric chains of mannuronic acid and gulunoric acid. The content of alginate in algae depends on the type of algae. The largest content of alginate (30-40% dry weight) can be obtained from Laminariales type while Sargassum Muticum, contains only 16-18% dry weight.

The compound is a linear polymer composed by two monomeric units, namely β-D-mannuronic acid and α-L-guluronic acid. The commercial seaweed as a producer of alginate derived from the genus of laminaria, lessonia, ascophyllum, sargassum, and turbinaria.

Types of alginate seaweed include Laminaria (Norway, France, China, Japan, Korea), Lessonia (Chile), Ascophyllum (Scotland, Ireland), Ecklonia (Japan, Korea), Macrocystis (Australia, North America), Sargassum and Turbinaria (Indonesia, Philippines).

Among the types of seaweed that are found to grow abundant naturally in Indonesia’s marine waters are Sargassum and Turbinaria. However, the two types that have been utilized by the alginate industry in Indonesia only type of Sargassum because it is easier to obtain and contains more alginate than Turbinaria.

Alginate from various species of brown seaweed often have variations in chemical structure, resulting in different physical properties. For example, some can produce alginate which gives a strong gel, the other one is a weaker gel; some can easily provide white cream / alginate, while others are difficult to gel, and are best used for technical applications where color is not important.

The principle of obtaining alginate

Alginate extraction process is carried out in an alkaline atmosphere (addition of Na2CO3 solution), because alginate is soluble in base and insoluble in acid. Algae are washed, then dissolved in alkali, namely sodium carbonate solution. After the cellulose is lost, the alginate can be separated by precipitation in the form of calcium salt or alginic acid.

When the result of calcium alginate, the precipitate should be washed with acid so that the result turned into alginic acid, then added base to obtain the desired type of salt. Generally alginate manufacture consists of selection, cutting, immersion, precipitation and purification.

Alginate is usually used in the form of salts such as Sodium salt, Calcium, Potassium and Ammonium and also in the form of esters such as Propylene glycol alginate.

What is Sodium Alginate?

Sodium alginate is a sodium salt of alginic acid. The empirical formula is NaC6H7O6. Physical characteristics of sodium alginate is in the form of flour or fiber, white to yellowish, almost odorless, and tasteless.

In addition, the chemistry process used to extract sodium alginate from brown seaweed is relatively simple. Process difficulties arise from the necessary physical separation, such as the need to filter out slimy residues from viscous solutions or to separate the gelatin precipitates which hold large amounts of fluid in the structure and which retain filtration and centrifugation.

Commercial sodium alginate has a molecular weight of 32,000-200,000 with a degree of polymer from 180 to 930. The alginic acid and Calcium salt are very slightly soluble in water, whereas the salt of Sodium, Potassium and Ammonium and Propylene ester is soluble in hot and cold water. Commercial sodium alginate has a molecular weight of 32,000-200,000 with a degree of polymer from 180 to 930. The alginic acid and Calcium salt are very slightly soluble in water, whereas the salt of Sodium, Potassium and Ammonium and Propylene ester is soluble in hot and cold water.  

The process for preparing sodium alginate from brown seaweed falls into two categories:

1. Calcium alginate method

In alginat extraction process, there is acid treatment (acid pre-treatment) first. Calcium alginate reacts with acids and is converted to acid alginate. Extraction stage is carried out to convert alginate to dissolve easily by adding a solution of Sodium Carbonate (Na2CO3) on seaweed which has undergone acid treatment.

With this treatment, the solution becomes thick like a paste consisting of dissolved sodium alginate and the rest of seaweed. Filtration / filtration is done to separate dissolved sodium alginate of residual seaweed that is not soluble in alkali, especially cellulose. Separation done using filter press which consists of a fine filter cloth, filter aid, or metal filter (120-200 mesh).

2. Alginic acid method.

Then what are the uses of Sodium Alginate? Here they are.

Uses of Sodium alginate :

  1. It is used in the printing of reactive dyes and as a thickener for reactive dyes in textile screen printing. Alginate does not react with this dye and wash easily, unlike starch-based thickener. (Read also Banned Chemicals in Textiles, Chemicals Used in Dyeing Industry)
  2. Sodium alginate is used as an impression-making material in dentistry, prosthetic, lifecasting and to create a positive for small-scale casting.
  3. Sodium alginate is widely used in liquid medicine industries because it can increase viscosity.
  4. Sodium alginate is also used in the pharmaceutical industry, for example as tablet binder of penicillin and sulfa drugs.
  5. Sodium alginate and calcium alginate are emulsifiers that can
    used in capsule making.
  6. Sodium alginate has uses include: binding water (used in cosmetics,  glue, frozen food, cakes fill, syrup),
  7. As an emulsion (used on meat and vegetables),
  8. As stabilizers (used in beer drinks, and fruit juices),
  9. It is used in gelling  (used on pudding instant, and thin silk fabric)
  10. Sodium alginate is also used as a slimming agent ‘, ie by forming a jelly in the stomach that will provide a sense of satiety.

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In addition, uses of Alginate in general, as follows :

  1. Alginate in the industrial field is usually used as:
    pharmaceuticals as emulsifiers, stabilizers, suspended agents in the manufacture of tablets, capsules
  2. Alginate in cosmetic industries : as an emulsifier in the manufacture of creams, lotions and sauces.
  3. Alginate in food industry : as a stabilizer, additive.
  4. Alginate serves as a keeper of tissue forms in frozen foods, counteracting and hardening in the sugar-coated bakery industry, suspending in syrup. (Read also List of Food Preservatives, Chemicals allowed in organic food)
  5. Emulsifiers in salad dressings, as well as the addition of foam in the beer industry.
  6. In the field of alginate biotechnology used sebgai algin-immobilized cells from yeats in the process of alcohol production.

That’s all the uses of uses of sodium alginate. Hope this article is helpful. Thanks.