Agar (agar-agar, E406) – properties and use

Agar (agar-agar, E406) is a gelling substance that is obtained from naturally occurring marine algae. that’s why its other name is sea gelatin. Thanks to its gelling properties, agar has been widely used in the food industry not only. Check if the agar is healthy and how to use it.

Agar, also known as agar-agar or E406, is a natural plant-derived substance that is used in industry and households as a gelling and thickening agent. It is a component of the cell walls of marine algae, more precisely, the algae of the family of the Krasophytes. Agar belongs to polysaccharides. It is a mixture of agarose and agaropectin.

Agarose constitutes about 70% of the agar composition and its gelling ability depends on its content. Agarose is a large linear molecule made up of alternating units of D-galactose and 3,6-anhydro-L-galactose monosaccharides. The agarose to agaropectin ratio is variable and depends on the type and species of seaweed used to produce the agar.

Different varieties of agar have different gel strength and gel stiffness. In addition, the content of agarose and agaropectin in plant cell walls depends on the season and hydrodynamics of the environment, i.e. water movements.

How agar looks naturally
How agar looks naturally

Agar (agar-agar, E406) – properties

Agar is most often available in the form of powder, leaves, cubes or threads. Powdered is used in industry, and other forms for cooking dishes. It is colorless, has no taste and smell.

It dissolves very well in boiling water. However, it does not dissolve at all in cold water and alcohol. In cold water, the agar swells, dissolves at 85 degrees Celsius, and during cooling it solidifies at 34 – 43oC, forming a gel solid reminiscent of a chilled jelly.

Why is agar a valuable gelling agent in the industry?

Agar (agar-agar, E406) – application

Agar is used in the food industry as a gelling, stabilizing and viscosity controlling agent. It is marked with the symbol E406. It is a food additive, not a nutrient, because the human body digests it only by 10%. The agar’s gelation ability is so great that it is used at a maximum concentration of 1.5%, so its consumption is very low.

Agar is the longest used colloid derived from plants. It has been used as a food additive in the Far East for over 300 years, and in Western countries for over 100 years. It is a completely safe food additive. This confirms its long-term use as well as the opinions issued by expert groups from FAO / WHO and FDA.

In what foods can agar be used?

Agar can be used for cooking and baking instead of gelatin. It works in the preparation of fruit and meat jellies, cold cheesecakes or desserts. This is a vegetarian product. It solidifies slightly faster than gelatin. It surpasses it in that it has no taste and smell and is transparent.

Different types of agar have different gel strength, so always read the label. The amount of agar that corresponds to 1 teaspoon of gelatin is 1/2 to 2 teaspoons. In a more acidic environment, it can be added a bit more because it gels weaker.

In addition to the food industry, agar gelling properties are also used. It is used primarily as a substrate for the growth of microorganisms in microbiological laboratories. In addition, casting forms are made of 8% agar solution, it is used in sculpture and archeology. Agar is also used when making dental castings.

Agar based molds are more expensive than others, but much more accurate. Agar is used as a filler in the production of pharmaceutical preparations. It is also known as a laxative that swells in the intestines and facilitates defecation with large amounts of water. It can be classified as soluble fiber dietary fractions.

Agar is used in plant nurseries, in the cloning technique, including orchids. Agarose – the main component of agar is used in biochemistry and biotechnology. It can be used for protein separation, in the production of biotechnological insulin, interleukin and other, diffusion, chromatography and electrophoresis techniques.

Agar comes from Japan, where it was discovered in 1658 by the innkeeper Tarazaemon Minoy. There is a legend that he discovered agar after cooking red algae soup, which after cooling turned into jelly. In the 17th and 18th centuries, agar spread to other Asian countries, where it became an important element of local cuisine.

He came to Europe in 1859 thanks to the French chemist Anselm Payen, who spread it as a Chinese foodstuff. In 1882, Robert Koch’s assistant, microbiologist Walter Hesse described the possibilities of using agar as a medium for growing microorganisms in microbiological laboratories. Since then, its popularity in the western world has grown rapidly.

Until World War II, almost all agar production was concentrated in Japan. Spain and Chile became the next big agar producing centers.

Agar (agar-agar, E406) – how do you get it?

Originally, agar was obtained from Gelidium dwarfs and it was these seaweed that were the source of the agar with the strongest gelling properties. Other types gave a product with poorer properties, which is why they were called agaroids. Currently, all these gelling substances are called agar, but very often the name agar in the name is added to the name of the type of seaweed from which it was obtained. In other regions of the world, other dwarf algae are used to produce agar

Seaweed is grown in underwater farms. Different types require a different substrate. For example, Gelidium grows best on rocky ground, and Gracilaria – sandy.

The algae are harvested, washed and hand washed to separate mechanical impurities and other seaweed. Then boil in boiling water with the addition of vinegar or sake. The extract is filtered hot through a cotton fabric, poured into wooden trays and cooled to gel.

The gel cut into rectangular posts or pressed in the form of threads resembling spaghetti is spread on bamboo screens and left for 1 or 2 nights for total concentration in the open air, facing the north winds. After concentration, the gel is sprayed with water during the day to dissolve. The agar is then sun-dried.

The traditional agar extraction method is now rarely used by Japanese artisans and is of marginal importance compared to global industrial production. Traditionally obtained agar does not have reproducible properties that are extremely important in large-scale production processes.

Agar agar can be used as a gelatine substitute  in jellies!
Agar agar can be used as a gelatine substitute in jellies!

After harvesting, the seaweed is washed and cleaned, and then dried to avoid agar-destroying fermentation. Then they are pressed with a hydraulic press, which reduces their volume and therefore transport costs. The process of producing agar from Gelidium and Gracilaria algae takes place in a slightly different way, because Gracilaria has many more sulfuric acid residues that reduce the gelling ability of the agar.

Gelidium is warmed in a mild sodium carbonate solution to remove dyes. Gracilaria is treated with 0.5 to 7% sodium base for desulphurisation and subsequent washing. The next stages apply to all dwarfs.

These include extraction or extraction of agar from the seaweed cell walls, filtration or purification of unwanted ingredients, and freezing gelation.

Gelidium agar is thawed and frozen several times and then whitened. With gracilaria agar, the freezing-thawing stage is omitted, while syneresis is carried out, which results in the formation of a very concentrated gel. Agar was dried and they had.