how is red algae extract (carrageenan) collected?

Carrageenan is a biopolymer extracted from red algae or Rhodophytes. These marine algae are mainly found in Europe (Atlantic Ocean, English Channel, North Sea). There are various varieties of red algae, such as Chondrus crispus, Mastocarpus stellatus and Furcellaria fastigiata.

A little anecdote: The name "carrageenan" comes from the Celtic "lichen carrageen" meaning "Irish moss". Sailors used to use it to prepare jelly desserts by adding a handful of bleached seaweed to their milk.

Today, these compounds are still present in the food industry, but are also widely found in skin and hair care. Carrageenans are sulfur-containing polysaccharides that are used to thicken food and give them a gel-like consistency. Indeed, they contain sulfated D-galactose residues. In contact with water, these biopolymers expand and form a gel-like network. Moreover, carrageenans also have benefits for the skin. They are humectants, which means that they have the ability to retain water, improving the overall appearance of the skin. They can also stimulate the natural production of hyaluronic acid and ceramides, reinforcing the waterproofness of the epidermis and limiting the insensible loss of water. That's why we use red algae extract or carrageenan in skin care.

The process of extraction of carrageenans from red seaweed involves several steps, which are described below:

1. The red algae are harvested and cleaned to eliminate sand as well as non-algal residues. It is then dried in the sun. The percentage of humidity should not be lower than 35% to preserve the quality of the carrageenan, while avoiding the deterioration of the algae;

2. The dried seaweeds then undergo a vigorous mechanical agitation in an alkaline aqueous medium (presence of sodium or calcium hydroxide or sodium carbonate). These conditions ensure the formation of 3,6-anhydro bonds between the polymeric chains, which increases the gelling capacity of the carrageenans;

3. The reaction medium is directly filtered or centrifuged in order to eliminate all insoluble residues;

4. The obtained solution is then concentrated by evaporation or ultrafiltration;

5. A precipitation reaction in an alcohol (most often isopropanol) or with potassium chloride allows to recover the carrageenans in solid form;

6. The carrageenans are then pressed to get rid of the liquid as much as possible. Then, they are dried and crushed. A powder with a high yield of about 25% compared to the initial mass of dry seaweed got created.