The INDONESIAN agar production process

Cleaning and washing

The first step in the production process is the cleaning and washing. This step is necessary to remove any foreign material such as sand, salts, sticks and any debris, which may appear naturally with the seaweed.


Gracilaria must be treated with alkali before extraction to obtain the optimal gel strength. For the alkali treatment, the seaweed is heated in 2 – 5% sodium hydroxide at 85 – 90°C typically for one hour. After the removal of the alkali, the seaweed is washed with water, and sometimes with weak acid to neutralize any residual alkali.


The next step is the  extraction of the Agar from the seaweed. The Agar is extracted by heating in water for several hours. During this process the Agar dissolves in the water. The mixture is then filtered to remove the residual seaweed.

COOLING and washing

The hot filtrate is cooled and forms a gel, which contains about one percent Agar. The gel is broken into pieces and washed to remove all soluble salts, and, if necessary, it can be bleached to reduce the color.


After this step, water is removed from the gel mostly through a gel pressed system.


Remaining water can then be removed by drying. The final step is to mill the Agar to a suitable and uniform particle size.

find your agar supplier

Of the ASTRULI member companies eight members produce Agar as an end product and one produces alkali treated Gracilaria.