As long as 5000 years ago, seaweed was used as a food and medicine in China. And today it is still eaten around the world. It is found in the Japanese fish and rice dishes sushi, in Welsh laver bread (seaweed fried with oatmeal) – and in ice cream.
Seaweeds provide ingredients called alginates and carrageenans, which are used in ice cream as stabilisers, so that ice cream does not become grainy in the freezer.
When ice cream is made, most of the water content freezes into very small ice crystals about 50 microns in size. (A micron is 1000th of a millimetre). As the thermostat of a deep freezer switches the refrigeration off and on, the temperature in the freezer fluctuates. Water melts off the crystals as the temperature rises, causing smaller ones to disappear. Then as the temperature drops again, the water freezes on to the remaining crystals, which grow in size. This causes the texture to coarsen.
Stabiliser slow the growth of the ice crystals, by forming protective layer around them, so the ice cream retains its smooth texture longer.
Carrageenan is obtained from red seaweeds found around rocky shores in northern Europe and North America. The seaweed is harvested, then dried to preserve it. Carrageenan can be extracted by immersing the dried seaweed in hot water. The extract is purified and then ground to a fine, cream-coloured powder. Alginates are exhorted in a similar way from brown seaweed in several parts of the world.
Before being used in ice cream, the alginate or carrageenan is usually blended with other compounds such as guar gum (extracted from the seed of the guar plant of India and Pakistan) and Locust bean gum (from the seeds of the Locust bean or carob tree, which grows in the Mediterranean area) to provide mixtures which are more effective than a single stabiliser.
Stabilisers are used in ice cream at about 0.2% of weight, so that a litre of ice cream contains less than a gram of the seaweed extract.
Picture Credit : Google