Brown Seaweeds Used in Making Alginate
THE STORY OF ALGINATE BEGINS WITH SEAWEED
A wide variety of brown seaweeds of the phylum Phaeophyceae are harvested throughout the world to be converted into the raw material commonly known as sodium alginate. Sodium alginate has a wide use across a wide variety of industries including food, textile printing and pharmaceutical. Dental impression material utilizes alginate as its means of gelling. Since alginate is a product of seaweed it is both food and skin safe. EnvironMolds uses sodium alginate in all it's mold making alginate formulations. This is the story of how alginate is produced rom beginning to end.
HARVESTING BROWN SEAWEED FOR ALGINATE PRODUCTION
Seaweeds can be classified into three broad groups based on pigmentation: brown, red and green. Botanists refer to these broad groups as Phaeophyceae, Rhodophyceae and Chlorophyceae, respectively. Brown seaweeds are usually large, and range from the giant kelp that is often 20 m long, to thick, leather-like seaweeds from 2-4 m long, to smaller species 30-60 cm long.
Alginates are refined from brown seaweeds throughout the world. None of the usual seaweeds for alginate production are cultivated. They cannot be grown by vegetative means, but must go through a reproductive cycle involving an alternation of generations this makes cultivated brown seaweeds too expensive when compared to the costs of harvesting and transporting wild seaweeds. The only exception is for Laminaria japonica, which is cultivated in China for food but the surplus material is diverted to the alginate industry in China.
Alginates from different species of brown seaweed often have variations in their chemical structure, resulting in different physical properties. For example, some may yield an alginate that gives a strong gel, another a weaker gel; one may readily give a cream/white alginate, another may give that only with difficulty and is best used for technical applications where color does not matter.
Mechanical seaweed harvesting vessel.
Saccharina Japonica being harvested and hand dried.
Processing of brown seaweed to produce sodium alginate.
Final processing of finished sodium alginate.
In some countries, including China, the seaweed is hand dried in the open either on lines as in the above photo, or laid out on the ground for drying. Other countries use more efficient rotary driers and even heat. Once dried the seaweed is pulverized in mills before being shipped to factories to be converted into sodium alginate
To learn more about the conversion process to sodium alginate click here.