Note

Date 1996

Event ID 1182884

Category Descriptive Accounts

Type Note

Permalink http://canmore.org.uk/event/1182884

Alginates are naturally occurring material (alginic acid) extracted from brown seaweed and are used in textile printing, paper manufacture, welding rods, and ceramic, pharmaceutical and dental compounds to name but a few. It is in the food and drink industry that it is mostly used to control the water content in fruit gels, suspending agents in soft drinks, cold water gels with milk based deserts, prevention of ice crystals in ice cream and to aid to beer foam stability in the brewing industry. Algin or alginate was first isolated in 1883. Red seaweed produces agar and

Production Process

The basic extraction process for all alginates is as follows: Brown seaweed is chopped up and mixed with hot water and sodium hydroxide and/or sodium carbonate to form a slurry. The alginate element forms a thick paste with the seaweed solids. This paste is diluted with cold water and the solids filtered out. Calcium chloride is then added to yield calcium alginate or dilute acid-like sulphuric acid to in turn yield alginic acid. Both of these precipitates are recovered as insoluble pulps. These pulps are reacted with sodium carbonate forming a dough of sodium alginate. This is then dried to produce the alginate.

Information from J Bailey, Research Chemist, Kelco International, Barcaldine, Oban, Argyll and Bute, February 1996.